Narva | Trailer Plug Wiring Diagram Guide 7 PIN HEAVY DUTY ROUND PLUG AND SOCKET . Manufactured in accordance with the SAEJ560 Standard and in accordance with the Australian Standard AS4735 2003 as required for vehicles and trailers over 3.5 tonnes. E Locker Wiring Installation | Page 2 | Tacoma World Took my kick panel off and lower dash cover to look for plugs. At first glance you would say they're not there. But factory workers taped them out of the way and after digging in I found both the switch plug and the 4x4 ECU plug. LED Turn Signals Bulbs | Tacoma World I just finished putting in my LED flasher that I got from superbrightleds and some bulbs. I turned the truck on and tested to see if the turn... Pinouts · AllPinouts It appears that you are using AdBlocking software. The cost of running this website is covered by advertisements. If you like it please feel free to a small amount of money to secure the future of this website. Upgrading a Car Radio (for a Toyota Corolla): 8 Steps Upgrading a Car Radio (for a Toyota Corolla): A step by step guide to replacing the factory cassette radio in a Corolla with a mp3 WMA CD player and radio.Select the replacement audio. You can obtain CD player with mp3 and WMA from Walmart for $89. The most important features are the abilit... Bargman | etrailer Bargman experts, complete product offering and experienced knowledgeable product support. Lowest Prices for Bargman products. Expert service, Bargman reviews and comparisons, order online at etrailer or call 800 298 8924. LED Turn Signals Blinking Too Fast (Hyperflashing) Super ... Hyperflashing is when the turn signals blink faster than your stock incandescent bulbs did. This happens because your new LED bulbs draw such little power that your turn signal relay sees the bulbs as being out. No worries—it's an easy fix! Read the full guide on how to correct hyperflashing in turn signals. TOYOTA 2014 YARIS MANUAL Pdf Download. Page 1 TABLE OF CONTENTS Adjusting and operating features such as door locks, Before driving mirrors, and steering column. When driving Driving, stopping and safe driving information. Interior Air conditioning and audio systems, as well as other in features terior features for a comfortable driving experience. TOYOTA 86 OWNER'S MANUAL Pdf Download. Page 1 TABLE OF CONTENTS Adjusting and operating features such as door locks, Before driving mirrors, and steering column. When driving Driving, stopping and safe driving information. Air conditioning and audio systems, as well as other in Interior features terior features for a comfortable driving experience. Toyota 4Runner and Pickup: Cheap Tricks 4Crawler [Click above thumbnails for a larger image] Note: On later model trucks, there is no separate fuel pump test connector, rather you have to use the diagnostic test connector (shown in photo C above) and follow the test procedure outlined in the Factory Service Manual, which involves placing a jumper wire between the "Fp" and "B " terminals (see photo D). 3157 4157 led bulb tail light turn signal parking brake ... 3157 3156 4157 led light bulb tail light turn signal parking brake backup 3057 3155 3156 3157ll 3357 3457 3757 4057 4114 4114k 4157 4157ll taillight Mercedes older series diagnostic fault code reading. W124 ... Mercedes older series diagnostic fault code reading. W124.R129 1980's – 1990's era. As you are reading this you will probably be wishing to extract a fault code or clear a fault indicator lamp from the dashboard of your older Mercedes Benz model vehicle. Bentley Auto Ersatzteile, Bentley Car Spare Parts ... 2040, press tool tube, ase40537900000, hv test adapter, 3w3807833c, headlight trim, rh14994k6a, paint sample barnato 2086, tool extractor hook, ase40538301000, high ... The Car Hacker's Handbook OpenGarages About the Author. Craig Smith ([email protected] ) runs Theia Labs, a security research firm that focuses on security auditing and building hardware and software prototypes.He is also one of the founders of the Hive13 Hackerspace and Open Garages (@OpenGarages). He has worked for several auto manufacturers, where he provided public research on vehicle security and tools. KLR650 FAQ Big Cee Studios Parts Accessories: Fred Hink Arrowhead Ron Ayers Bike Bandit Ebay KwikSpecs Front KwikSpecs Rear. KLR 250 Information Exchange. This is intended to be a FAQ, not a service manual or encyclopedia. The service manuals are a good thing to have (either the factory manuals or the Clymer book.) Engine Section in the forums of FZ750 ID date name subject text 1 28 02 2004 12:19:05 Ticeman Engine swap Unbolt the old. Bolt the in the new. Anything but a YZF engine.


text:
SpaceX Launching Its Third Mission in Less Than Two Weeks
SpaceX launching yet another Falcon 9 rocket, the third launch in two weeks.
July 3, 2017 13:00 IST
Image Credit: Public Domain
In the first half of 2017, SpaceX has already broken its previous record for launches in a single year. Although, they are planning for almost 20 launches in 2017. Now, in less than two weeks, SpaceX is launching its third mission. The mission is to put a massive communications satellite into orbit for the company Intelsat.
Ken Lee, senior vice president for space systems for Intelsat said, "I would have no qualms about using the pre-flown hardware in the future once they have fully demonstrated their reusability," which he defines as "[t]ypically…a minimum of three."
This launch will be the third launch in just nine days and the 39th Falcon 9 rocket launch. The takeoff is scheduled on Tuesday, July 4, at 7:37 p.m. EDT, or 23:37 UTC from Kennedy Space Center in Florida. What sets this launch apart from the other recent missions is that the client is not interested in utilizing reusable rocket tech.
As SpaceX plans, it is important to Intelsat, and likely other entities looking to use SpaceX's tech to get into space.
The probe, called Intelsat 35e, weighs more than 13,000 pounds, making it one of the heaviest satellites SpaceX has ever launched. It's also going to a particularly high orbit above Earth called geostationary orbit, a path 22,000 miles up. Meanwhile, the Falcon9 will have to burn a lot of fuel to get the satellite where it needs to go.
This will be the pretty impressive launch for the company. Typically, the number of launches a company will pull off each year hovers somewhere in the single digits or maybe a dozen or so at best. But this launch will be the third mission of this year.
Lee said, "SpaceX offered to use a pre-flown rocket for the Intelsat 35e satellite, but Intelsat declined."
"We have ongoing conversations about how many successful missions are needed before we consider that to be a reliable launch vehicle. Typically, there's a minimum of three."
UPDATE: This article was updated to include mission's new launch time.
REFERENCESpaceX

redpajama_set_name: RedPajamaCommonCrawl


A system and method for self-diagnosing a likely cause of a system crash is disclosed. A mechanism within an operating system checks for the existence of a stop code at startup of the machine. The existence of the stop code indicates that the system crashed during the previous session, and the type of system crash. The mechanism may read the stop code and implement a self-diagnostic procedure that corresponds to that stop code. In this manner, the mechanism may automate many of the tasks normally performed by humans, such as a system administrator, to self-diagnose the likely cause of the crash. If the crash occurs again, the mechanism, through the tracking procedures automatically implemented, may identify and report to a system administrator the likely cause of the crash, e.g. the particular faulty driver or configuration error.
The present invention relates to computer system crash analysis. More specifically, the invention relates to the identification of a component responsible for a computer system crash.
Today, diagnosing a computer system crash (due to operating system or device driver software bugs, hardware errors, configuration problems, or the like) is a very time consuming and expensive process. Typically, a system administrator or developer is left to access books, websites, or colleagues, and often resorts to trial and error to determine what exactly caused the system crash. The diagnosis is generally manual and involves setting particular diagnostic configurations, rebooting the system (likely many times), manually evaluating the diagnostic results, and attempting to reproduce the crash.
In some operating systems, when a crash occurs, a dump file may capture the operating state of the computer at the time of the crash. The traditional dump file helps solve the mystery of what caused the crash, but is typically a very large file. For instance, large systems may have several gigabytes of memory. Writing out the traditional dump file may take upwards of thirty minutes on such a system. Users typically disdain that much down time, and administrators prefer to avoid such time-consuming steps toward diagnosing the system crash.
Moreover, as suggested above, using the information stored in the dump file has traditionally been a time-intensive, manual process. A system administrator or developer is left to read many lines of information in an attempt to determine what caused the crash. Hours of human intervention may be spent simply identifying the diagnostic steps to be taken in search of the offending component that caused the crash.
Further complicating the diagnosis of system crashes is that they are often difficult to reproduce. For example, a device driver may have a bug that does not arise unless memory is low, and then possibly only intermittently. In that case, a test system may not be able to reproduce the error because it does not reproduce the conditions.
In sum, diagnosing system crashes has long vexed system administrators and users of computing systems. A system that overcomes the problems identified above has eluded those skilled in the art.
Briefly described, the present invention provides a system and method for self-diagnosing system crashes by identifying a type of system crash that occurred, and automatically taking diagnostic steps based on that type of crash. The invention may make use of a stop code contained in a memory dump file stored in response to the system crash. Preferably, the invention makes use of a "minidump" that contains an intelligently selected subset of the available pre-crash computer information, including the stop code that identifies the particular type of crash that occurred.
In one implementation, a mechanism of an operating system is configured to write an abbreviated dump file of a selected portion of the system memory at the time of a system crash. For example, a "crash driver" may be implemented that, when instructed by the operating system, reads from system memory certain information considered to be likely the most relevant to the diagnosis of a system crash, and writes that information to the dump file. Typically, a component of the operating system (e.g., a memory manager component) identifies the occurrence of a system fault, such as corrupt or exhausted memory, and informs the operating system that the system crash has occurred. In response, the crash driver may be instructed to write the dump file so that the crash may be diagnosed.
In accordance with an aspect of the invention, another mechanism within an operating system, such as a memory management component of a system kernel, checks for the existence of the dump file at each startup of the machine. The existence of the dump file may indicate that the system crashed during the previous session. The existence of the dump file is but one technique that may be used to determine that a system crash occurred, and is only given as an example. In any case, once the occurrence of the system crash has been discovered, the mechanism of the invention analyzes the dump file to determine what type of crash occurred (e.g., out of memory or corrupt memory), and implements a self-diagnostic routine or procedure corresponding to the type of crash. More particularly, the mechanism may read the stop code from the dump file and implement a self-diagnostic procedure that corresponds to that stop code.
In accordance with another aspect of the invention, during startup, the mechanism may change the stop code stored in the dump file to avoid a situation where the system suffers another, different type of crash before the mechanism is able to address the first crash (such as later in the startup process).
FIGS. 11 and 12 are functional block diagrams illustrating components of the self-diagnostic system used to diagnose various types of system crashes resulting from corrupt memory.
FIG. 1 and the following discussion are intended to provide a brief general description of a suitable computing environment in which the invention may be implemented. Although not required, the invention will be described in the general context of computer-executable instructions, such as program modules, being executed by a personal computer. Generally, program modules include routines, programs, objects, components, data structures and the like that perform particular tasks or implement particular abstract data types.
Moreover, those skilled in the art will appreciate that the invention may be practiced with other computer system configurations, including hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers and the like. The invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.
With reference to FIG. 1, an exemplary system for implementing the invention includes a general purpose computing device in the form of a conventional personal computer 20 or the like, including a processing unit 21, a system memory 22, and a system bus 23 that couples various system components including the system memory to the processing unit 21. The system bus 23 may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. The system memory includes read-only memory (ROM) 24 and random access memory (RAM) 25. A basic input/output system 26 (BIOS), containing the basic routines that help to transfer information between elements within the personal computer 20, such as during start-up, is stored in ROM 24. The personal computer 20 may further include a hard disk drive 27 for reading from and writing to a hard disk, not shown, a magnetic disk drive 28 for reading from or writing to a removable magnetic disk 29, and an optical disk drive 30 for reading from or writing to a removable optical disk 31 such as a CD-ROM, DVD-ROM or other optical media. The hard disk drive 27, magnetic disk drive 28, and optical disk drive 30 are connected to the system bus 23 by a hard disk drive interface 32, a magnetic disk drive interface 33, and an optical drive interface 34, respectively. The drives and their associated computer-readable media provide non-volatile storage of computer readable instructions, data structures, program modules and other data for the personal computer 20. Although the exemplary environment described herein employs a hard disk, a removable magnetic disk 29 and a removable optical disk 31, it should be appreciated by those skilled in the art that other types of computer readable media that can store data that is accessible by a computer, such as magnetic cassettes, flash memory cards, digital video disks, Bernoulli cartridges, random access memories (RAMs), read-only memories (ROMs) and the like may also be used in the exemplary operating environment.
A number of program modules may be stored on the hard disk, magnetic disk 29, optical disk 31, ROM 24 or RAM 25, including an operating system 35 (preferably the Windows® 2000 operating system). The computer 20 includes a file system 36 associated with or included within the operating system 35, such as the Windows NT® File System (NTFS), one or more application programs 37, other program modules 38 and program data 39. A user may enter commands and information into the personal computer 20 through input devices such as a keyboard 40 and pointing device 42. Other input devices (not shown) may include a microphone, joystick, game pad, satellite dish, scanner or the like. These and other input devices are often connected to the processing unit 21 through a serial port interface 46 that is coupled to the system bus, but may be connected by other interfaces, such as a parallel port, game port or universal serial bus (USB). A monitor 47 or other type of display device is also connected to the system bus 23 via an interface, such as a video adapter 48. In addition to the monitor 47, personal computers typically include other peripheral output devices (not shown), such as speakers and printers.
The personal computer 20 may operate in a networked environment using logical connections to one or more remote computers 49. The remote computer (or computers) 49 may be another personal computer, a server, a router, a network PC, a peer device or other common network node, and typically includes many or all of the elements described above relative to the personal computer 20, although only a memory storage device 50 has been illustrated in FIG. 1. The logical connections depicted in FIG. 1 include a local area network (LAN) 51 and a wide area network (WAN) 52. Such networking environments are commonplace in offices, enterprise-wide computer networks, Intranets and the Internet.
FIG. 2 is a functional block diagram that, together with the following discussion, provides a general description of an illustrative self-diagnostic system 200 constructed in accordance with the present invention. Components of an illustrated embodiment of the system 200 include a memory manager 201, which may be a kernel-mode component of the operating system 35, a crash driver 203, and a boot loader 205. Also illustrated are one or more kernel-mode device drivers 207, a non-volatile storage device, such as the hard disk 27, and several pages of the system memory 22. The several components of the system 200 are illustrated as separate from the system memory 22 for clarity of explanation, but those skilled in the art will appreciate that those components may reside within the system memory 22 during execution.
The memory manager 201 of the described embodiment is a kernel-mode operating system component that (among other things) implements on-demand-paged virtual memory. The memory manager 201 allocates and deallocates memory, pages data into and out of physical memory (from and to a disk) as memory demands dictate, and generally maintains the flow of data into and out of system memory 22. The memory manager 201 performs such tasks to make it appear to other software components, such as application programs 37 or the drivers 207, that there is more memory available (e.g., four gigabytes of virtual memory) than the physical random access memory actually installed on the computer 20 (e.g., 128 megabytes of RAM). For example, when a driver needs memory, it requests a certain amount from the memory manager 201, which then allocates the memory (if available) to the driver. The memory manager 201 may trim data stored in the allocated memory to hard disk if not actively used by the driver, thereby freeing the physical memory for use by another component until again used by the driver.
The crash driver 203 is a special type of system driver that is responsible for writing a dump file to the hard disk 27 in the event of a system crash. More specifically, if the memory manager 201, or some other component of the operating system 35, identifies a system memory fault, that component instructs the crash driver 203 to read selected data from memory 22 and write that data to the hard disk 27 as the dump file. The crash driver 203 is provided a stop code by the operating system 35 that indicates a particular type of fault that led to the system crash. For example, an out-of-memory fault may correspond to one stop code, while a corrupt-memory fault may correspond to another stop code. The component that identifies the system memory fault may provide the stop code to the crash driver 203. Although briefly described here, further discussion of the crash driver 203 and the method of creating the dump file can be found in copending U.S. patent application Ser. No. 09/549,814, filed on Apr. 14, 2000, entitled "Methods and Arrangements for Generating Debugging Information Following Software Failures," assigned to the same assignee as the present patent application, and incorporated herein by reference.
The boot loader 205 is a component of the operating system 35 that contains the code used to load the operating system 35 into RAM 25 at system start up. In one embodiment, the boot loader 205 is configured to query for the existence of the dump file in a particular location on the hard disk 27. For instance, if the crash driver 203 is configured to write the dump file to a pagefile on the hard disk 27, the boot loader 205 is configured to read the dump file from the pagefile at start up. In this embodiment, the existence of the dump file indicates to the boot loader 205 that the system crashed during the previous session. Other mechanisms may alternatively be used to indicate the occurrence of the system crash, such as a status bit or code that is tested at each start up, or any other technique. The boot loader 205 is further configured to extract the stop code and other pertinent information from the dump file and pass it to the memory manager 201 early in the boot process (i.e., prior to loading any device drivers 207). In that way, the memory manager 201 knows the type of crash that occurred and may take action (as described below) prior to starting any drivers.
The device drivers 207 are software components that make use of the system memory 22 to perform varied tasks associated with the operation of the computer system 20. Often device drivers are associated with hardware devices, such as a hard disk driver or sound card driver. However, some device drivers perform specialized functions and are not associated with a particular hardware device, such as an antivirus driver or a file encryption driver. The device drivers 207 interface with the memory manager 207 to request the allocation, deallocation, and general maintenance of memory 22. Very often device drivers are kernel mode components that execute with a privileged status, which provides them with certain access privileges to otherwise protected memory that results in improved efficiency and performance. However, an ill-behaved device driver executing with privileged status can cause system crashes by improperly accessing or maintaining memory 22. Often, the memory manager 201 can detect that an errant device driver caused a memory fault, but cannot detect specifically which device driver 207 caused the fault, leading to the need to diagnose the system crash to identify the errant driver.
FIG. 3 and FIG. 4 are a functional block diagram and a logical flow diagram, respectively, that together generally illustrate how the system 200 may detect and identify a system crash, and store information used by the system 200 to self-diagnose the cause of the system crash. To begin, as represented by block 401 of FIG. 4, the system 200 performs normally, meaning that ordinary memory maintenance and accesses occur, until a system crash is detected by the operating system 35, such as by the memory manager 201. When a system crash is detected (e.g., a memory fault), at block 403 the memory manager 201 identifies the type of crash that occurred and assigns a stop code 311 (FIG. 3) to that type. For instance, if the memory manager 201 detects a dangerously-low memory condition resulting from a device driver failing to release unneeded memory allocations, the memory manager 201 identifies the particular stop code 311 associated with that crash type. The memory manager 201 may refer to a lookup table or other listing that maps stop codes to memory faults or other crash types.
At block 405, the memory manager 201 indicates the occurrence of a system crash to the crash driver 203, such as by passing the stop code 311 to the crash driver 203. Other techniques may equally be used to inform the crash driver 203 of the crash.
At block 407, once the crash driver 203 has the stop code 311 and has been informed of the crash, the crash driver 203 reads certain data from memory 22 to capture the state of the system at the time of the crash. The data read from memory 22 is selected to allow effective analysis and diagnosis of the crash. Further detail on the selected data and the operation of the crash driver 203 may be found in the aforementioned U.S. patent application Ser. No. 09/549,814.
At block 409, the crash driver 203 writes the dump file 315 to the hard disk 27. In an embodiment described herein, the crash driver 203 writes the dump file 315 to a particular location on the hard disk 27, such as a pagefile or other known location on the hard disk 27. In that way, the existence of the dump file 315 may be easily verified during a subsequent start up operation. The stop code 311 is included within the dump file 315 when written to the hard disk 27. Alternatively, the stop code 311 may be written to the hard disk 27 or pagefile separately from the dump file 315.
At block 411, after the stop code 311 has been written to the hard disk 27, the operating system 35 may shut down the computer system 20 or otherwise notify the user of the system crash. In some situations, the operating system 35 may be able to avoid completely shutting down the computer system 20 despite the crash, such as by terminating certain executing applications or processes that are affected by the crash. In other situations, the operating system 35 will prompt for (or otherwise cause) a reboot of the system, such as the case where operating system information has been corrupted by the crash. At this juncture, the dump file 315 and the stop code 311 have been saved to the hard disk 27, and the system 200 is prepared to self-diagnose the cause of the crash in accordance with one aspect of the present invention.
FIG. 5 is a functional block diagram and FIGS. 6A and 6B are logical flow diagrams that, taken together, generally describe how the system 200 determines that self-diagnosis is appropriate, and how the system 200 performs the self diagnosis. As represented in FIG. 5, during system boot, the boot loader 205 is launched to load the operating system 35 into memory 22. In an embodiment of the invention described herein, at block 603, the boot loader 205 checks for the existence of the dump file 315 on the hard disk 27 to determine whether the system crashed during the previous session. As mentioned above, the dump file 315 may be stored in a page file on the hard disk 27 so that it may be easily located by the boot loader 205 at start up.
At decision block 605, a test is made to determine whether the dump file exists. If the dump file does not exist, the process illustrated in FIG. 6A proceeds to block 607, where the system continues to boot normally, and the boot process effectively terminates at ending block 609. If however, the dump file 315 does exist, the system suffered a crash during the previous session, and the process illustrated in FIG. 6A continues to block 611.
At block 611, the boot loader 205 retrieves the dump file 315 from the hard disk 27. As discussed above, the dump file 315 may reside in a pagefile or some other known location on the hard disk 27 for easy location by the boot loader 205. At block 613, the boot loader 205 retrieves the stop code 311 from the dump file 315, and, at block 615, passes the stop code 311 and the contents of the dump file 315 to the memory manager 201.
The process continues at decision block 621 illustrated in FIG. 6B, where the memory manager 201 determines if a corresponding diagnostic procedure exists for the stop code 311. Note that all possible system crashes for which a stop code exists may not have a corresponding diagnostic procedure. Thus, if the stop code 311 does not have a corresponding diagnostic procedure, the memory manager 201 may either execute a default diagnostic procedure (as illustrated by "Yes" branch of the decision block 623), or proceed to boot normally at block 625. If a default diagnostic procedure is executed, the process may continue to block 629.
If at block 621 a corresponding diagnostic procedure exists for the stop code 311, at block 627, the memory manager 201 executes the diagnostic procedure for the stop code 311. The diagnostic procedure may include first ensuring that the computer system, including any device drivers and configuration settings, is still in the same configuration as before the crash, in case an administrator or other person identified and remedied the cause of the crash prior to the first post-crash reboot. The memory manager may verify this by comparing the list of components in the dump file 315 with those in the currently-running system. If the system is still in the same configuration, the memory manager 201 modifies certain system variables (identified by the diagnostic procedure) to enable appropriate switches (e.g., debug/tracking/sandboxing/driver verification switches) and the like, for the particular stop code 311. With any appropriate system variables set, the particular driver that caused the previous crash likely will be identifiable upon the next crash because it will typically be caught by these safeguards much sooner, as described below.
At block 629, the system continues the start-up process until the operating system 35, the device drivers 207, and any other appropriate software modules have been loaded into system memory 22. At this juncture, the computer system 20 is ready for use, and the diagnostic system 200 is prepared to identify the cause of the previous system crash in the event that it reoccurs.
At block 631, the memory manager 201 monitors the system operation in accordance with the system variables set at block 627. For example, the memory manager 201 may maintain an allocation table 511 that tracks particular types of memory usage by the device drivers 207. To this end, as generally represented in FIG. 7, the memory manager 201 may maintain a verification block (e.g., 701 1-701 n) that points to an outstanding allocation table (e.g., 511 1-511 n) for each driver that requests or performs a particular type of memory operation if the previous crash resulted from that type of memory operation (as identified by the crash code 311). As generally represented in FIG. 7, the verification block (e.g., 701 1) comprises driver information including a count of the total allocations for this driver. Other information may be maintained in the verification block, such as various allocation information for this driver. The verification block 701 1 also includes a pointer to the outstanding allocations table 511 1 set up for a corresponding driver. The outstanding allocations table 511 1 tracks specific information about each pool allocation that the driver has been given that remains outstanding, i.e., has not yet deallocated. The information may include the allocation's virtual address, length, and information useful in debugging such as per-process caller information and the tag of the driver that allocated the memory, e.g., "TCP" for TCP/IP drivers.
Thus, for each memory allocation to a driver, the memory manager 201 may include an entry in the allocation table (e.g., 511 1) associated with that driver that requests or performs a particular type of memory operation if the previous crash resulted from that type of memory operation (as identified by the crash code 311). In that way, when the crash reoccurs, the allocation tables 511 1-511 n will likely identify which driver, drivers, or other software program being tracked is the offending culprit. Note that it is alternatively feasible to determine from the various counts if a given driver is consuming inordinate amounts of memory.
The system continues operating and the memory manager 201 continues monitoring the system operation until, illustrated by decision block 633, the system crash reoccurs and the process proceeds to block 635. When the system crashes again, the process illustrated in FIG. 6B moves to block 635. At block 635, the diagnostic mechanisms employed by the memory manager 201 contain an identification of each driver or software module that has outstanding memory operations of the type identified by the stop code 311. For example, if the stop code 311 indicates that the previous system crash occurred as a result of low memory, the allocation table 511 may indicate the drivers that had allocations and details about those allocations at the time of the crash. Thus, the memory manager 201 reports the results of the diagnostic procedure to the user or system administrator in the form of a printout or summary of the allocation tables, or any other form of report. In this manner, the user or system administrator may evaluate the results to help determine which driver or software component in the computer system caused the crash. For instance, in the illustrated example, one of the drivers may be associated with a much larger number of allocated pages at the time of the second crash relative to other drivers. That information indicates to the user or system administrator that that driver is likely the cause of the crash, and should be perhaps replaced or further tested. Thus, the system 200 is able to self-diagnose the cause of the previous system crash, and upon a subsequent crash, provide the user or system administrator with an identification of the likely culprit behind the crash.
To help further clarify the operation of the disclosed self-diagnostic system, the following discussion provides several specific examples of types of system crashes that may occur, and how the system 200 illustrated above may self-diagnose those types of crashes. The examples fall into two broad categories, out-of-memory/resources crashes and corrupt-memory crashes.
The first category of system crashes deals with a failure of a software component, such as a device driver, to deallocate memory resources that the component no longer needs, often referred to as a "memory leak." Memory leaks can occur, for example, if a driver unloads but still has allocated memory, or even when a driver is loaded but for some reason does not deallocate unneeded memory. Memory leaks can be difficult to detect, as they slowly degrade machine performance until an out-of-memory error occurs.
FIG. 8 is a functional block diagram illustrating one example of a stop code and illustrative self-diagnostic procedure that involves a crash due to allocated pages in memory not being deallocated. FIG. 8 illustrates the above-described out-of-memory error that involves the failure of a driver to properly deallocate its allocated memory when no longer needed, (including when the driver is unloaded). As is known, a process (e.g., of a driver) may request that a block of virtual address pages be reserved for use by the process (or even for another process). In that case, the memory manager 201 selects a number of virtual memory addresses to satisfy the request, and reserves those pages to the process. However, if a driver process fails to release virtual addresses that the driver no longer needs, (including when the driver unloads with pages still allocated thereto), then the amount of available virtual memory in the system will slowly decrease until a low-memory situation occurs, leading to a system crash.
To address a system crash of that type, the memory manager 201, upon the next startup, may begin tracking (e.g., via allocation tables 511 1-511 n) each request for and release of virtual memory. The memory manager 201 may track each driver that reserves memory pages, such as by adding an entry in the allocation table each time a device driver 207 issues a request to allocate memory, and by removing the entry if the device driver 207 later deallocates the memory. The entry includes information sufficient to properly identify which driver requested the memory, and may include additional information to aid diagnosis, such as the fields shown in FIG. 7, and the like. If the crash reoccurs, the various allocation tables can be examined to identify which driver or drivers (and/or processes thereof) appeared to have requested the allocation of virtual memory without appropriately deallocating those pages. For example, an unloaded driver may still have pages allocated thereto, or a driver has an inordinate amount of pages allocated thereto.
Another similar type of error, represented by FIG. 9, involves a crash due to available Page Table Entries (PTEs) being exhausted. As is known, when a device driver first accesses a virtual address previously allocated thereto, the memory manager 201 creates a page table entry (PTE), such as PTE 927, to map each virtual page (e.g., virtual page 746) to a location in physical memory (e.g., physical page 940). However, there are a limited number of PTEs that may be created or maintained by the memory manager 201. If a device driver fails to deallocate used memory and thereby cause the release the PTE when no longer needed, the result may be an exhaustion of available PTEs, leading to a system crash.
To address a system crash of that type, the memory manager 201, upon the next startup, may begin tracking (e.g., via a PTE usage table 909) each creation and release of PTEs in a manner similar to that described above for virtual memory pages. The memory manager 201 may track may track the usage of PTEs by each driver, such as by adding an entry in the allocation table each time a device driver 207 causes a PTE to be created, and by removing the entry if the device driver 207 later frees the memory corresponding to the PTE. The entry may include information sufficient to properly identify which driver requested the PTE, and may include additional information to aid in diagnosis, such as the number of PTEs created, the process of the driver that caused creation of the PTE, the process that called that process, a pointer to the memory descriptor list (MDL), and the like. If the crash reoccurs, the PTE usage table 909 can be examined to identify which driver or drivers had PTEs in use at the time of the crash. Thus, if a crash is resulting from a lack of available PTEs, the table 909 will likely identify which driver is using an inordinate amount.
FIG. 10 is a functional block diagram illustrating an example of another stop code and illustrative self-diagnostic procedure that involves a crash due to locked pages in memory not being released. As is known in the art, certain memory pages allocated to a software component may be trimmed to a pagefile if not actively used. This allows more addressable memory (termed "virtual memory") to be available than the amount of physical memory actually available. For example, as illustrated in FIG. 7, virtual memory page 744 and virtual memory page 746 are logically mapped to the same physical memory location. However, in the illustrated example, virtual memory page 744 was not actively used and was consequently trimmed to the pagefile 705, (as flagged in the PTE therefor), whereby virtual memory page 746 may be actively used.
A driver may request that certain memory pages (e.g., virtual memory page 747) be locked in physical memory so that the information stored in those pages will not be trimmed to the pagefile 705. This is sometimes done by drivers or software components that need to access certain data as quickly as possible, or simply to maintain constant mappings of virtual addresses to physical addresses. Drivers are supposed to unlock any pages when it is no longer necessary that the pages remain locked. If a driver fails to do so, and/or even worse, continues to lock additional pages as they are used, over time the number of available physical pages of memory decreases until a low-memory error occurs, leading to a system crash.
In this case, as illustrated in FIG. 10, at system start up, the memory manager 201 detects, by the stop code 311, that the type of crash that occurred corresponds to locked pages not being released by a driver. Thus, the memory manager 201 may initiate a tracking procedure to track pages in memory as they are locked and unlocked. For instance, the memory manager 201 may create and write information to an allocation table 1009 that identifies each request by a driver for locked pages in physical memory. The memory manager 201 may use the allocation table 709 to track each driver that requests a locked page, such as by adding an entry in the table 1009 for each request, and by removing the entry if the device driver 207 frees the page. The entry includes information sufficient to properly identify which driver locked the page, and may include additional information to aid diagnosis, such as the same general information maintained for tracking virtual memory allocations in general, as described above. Alternatively, simple counts of the locked pages of each driver may be maintained, which may help identify an errant driver, although not necessarily pinpoint the problem within the driver The memory manager 201 continues to track the locked status of pages in memory until the crash reoccurs (or, perhaps, until turned off through some external mechanism). In this way, if the crash reoccurs, the allocation table 1009 contains an entry for each locked page in memory with sufficient information to identify each driver that has locked the page. In this way, a system administrator or other debugger can analyze the allocation table 1009, for example to identify which driver has an excessive number of locked pages, thus identifying the offending driver.
Another category of system errors that lead to crashes is corrupt-memory. One way in which a component can corrupt memory is related to the way in which pooled system memory is arranged and used. For many reasons, including performance and efficiency, a common pool of system memory is made available to kernel mode components. Pooled memory is allocated by the memory manager 201 as a block, (e.g., in multiples of thirty-two bytes), with a header (e.g., eight bytes) at the start of each block. For example, if forty-four bytes of pooled memory are required by a driver, sixty-four are allocated by the memory manager 201, eight for the header, forty-four for the driver, with the remaining twelve unused. Among other information, the header includes information that tracks the block size. Then, when the memory is deallocated, the memory manager 201 determines whether this block may be coalesced with any adjacent deallocated blocks, to make larger blocks of memory available for future requests. If so, the header information including the block size is used to coalesce the adjacent blocks.
While this technique is highly efficient in satisfying requests for memory allocations and then recombining deallocated memory, if an errant component, such as driver 1107, writes beyond its allocated memory block, it overwrites the header of the subsequent block. For example, if a driver requests twenty-four bytes, it will receive one thirty-two byte block, eight for the header followed by the requested twenty-four bytes. However, if the driver writes past the twenty-fourth byte, the driver will corrupt the next header, whereby the memory manager 201 may, for example, later coalesce the next block with an adjacent block even though the next block may be allocated to another component. As can be appreciated, a multitude of errors may result from the corrupted header.
To further complicate matters, the memory manager 201 or the component having the next block allocated to it (or even an entirely different component) will likely appear responsible for the crash. Indeed, this type of error can be very subtle, such as if the header corruption occurs long after the initial deallocation, possibly after many other components have successfully used the same memory location.
Another way in which an errant driver may crash the system is when a driver frees pooled memory allocated thereto, but then later writes to it after the memory has been reallocated to another component, corrupting the other component's information. This may lead to a crash in which the other component appears responsible. Indeed, this post-deallocation writing can be a very subtle error, such as if the erroneous write occurs long after the initial deallocation, possibly after many other components have successfully used the same memory location. Note that such a post-deallocation write may also overwrite a header of another block of pooled memory, e.g., when smaller blocks are later allocated from a deallocated larger block.
To address these type of error, the memory manager 201 may isolate the memory that is provided to a driver in response to a request for pooled memory. In other words, when memory corruption is suspected, the memory manager 201 does not actually give the active drivers (or a subset of the active drivers) memory from the pool upon request, but instead provides the memory from another special location. In one alternative, a "driver verifier" tool may be used to perform various tests on certain drivers loaded in the system to identify the offending driver, i.e., the driver verifier component may be turned on to monitor the actions of active drivers that make use of pooled memory. A preferred driver verifier mechanism is described in copending patent application Ser. No. 09/447,501 entitled "Method And System For Monitoring And Verifying Software Drivers," filed on Nov. 23, 1999, assigned to the same assignee as the present invention, and the disclosure of which is hereby incorporated by reference.
FIG. 11 is a functional block diagram illustrating a special memory structure 1109 that detects memory corruption. As generally represented in FIG. 11, one of the tests that may be performed is the detection of memory corruption via writing to a section not allocated to the driver, i.e., memory misuse by overruns and underruns. To detect memory corruption, the memory manager 201 allocates driver memory from the special, non-shared pool 1109, and monitors that pool for incorrect access. More particularly, when a driver-to-be-tested (e.g., 1107) requests pooled memory, the memory allocated to the driver 1107 is placed on a separate page (that is not pageable to disk). To this end, the memory manager 201 returns a virtual address to the driver 1107 that is the highest possible address which allows the allocation to fit on the page, in a virtual memory page pool 1109, whereby the allocated memory is aligned with the end of the page. The remainder of the page that precedes the data, if any, is written with random data, which may comprise a recorded pattern or the like to detect underruns.
Attempts to access memory beyond the allocation buffer (within a page) are immediately detected as an access violation, as such an access is within the subsequent, "No Access" memory page. Note that writing before the beginning of the buffer will (presumably) alter the random data, and when the buffer is freed, this alteration will be detected. In either case, a bug check is issued, whereby the offending driver is identified in keeping with the present invention.
Note that underrun detection may be selected for drivers, such that the allocated memory is instead aligned with the beginning of the page. With this setting, underruns cause an immediate bug check, while overruns (may) cause a bug check when the memory is freed. In actual implementations, underrun errors tend to occur less often then overrun errors.
Another test of memory misuse that is performed is represented in FIG. 12, whereby when the driver 1107 deallocates memory from the special pool 1109, instead of freeing the virtual address space, the entire section is marked "No access." As a result, any subsequent read or write back to the formerly allocated area is also detected via an access violation. However, because memory space is finite, the system may needs to reuse the special pool 1109 at some time. To this end, the special pool is essentially arranged as a queue with respect to the deallocated pages. More particularly, once deallocated, a page is reused only after cycling through a large number (e.g., 50,000 or more) of allocations to other areas of the pool 1109. To this end, a pointer or the like to the appropriate virtual address in the pool 1109 may be maintained, e.g., to the address of the virtual next location in which space for allocating and bounding the allocated page is available. Note that a page that is still allocated and its surrounding "No Access" pages are skipped over such that only deallocated pages are reused.
While the invention is susceptible to various modifications and alternative constructions, certain illustrated embodiments are shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the invention to the specific form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention.
automatically initiating a self-diagnostic procedure associated with the stop code including performing operations to track memory usage by a software component.
2. The computer-readable medium of claim 1, wherein storing the information associated with the system crash includes identifying the particular type of system crash.
3. The computer-readable medium of claim 1, wherein reading the stop code comprises reading the information from a known location during the subsequent system startup.
4. The computer-readable medium of claim 3, wherein the known location includes a pagefile.
5. The computer-readable medium of claim 1, wherein the stop code is associated with a memory access error.
6. The computer-readable medium of claim 5, wherein the memory access error comprises an out-of-memory condition.
7. The computer-readable medium of claim 5, wherein the memory access error comprises a corrupt memory condition.
8. The computer-readable medium of claim 1, wherein initiating a self-diagnostic procedure includes activating a pre-determined set of system variables corresponding to the stop code.
9. The computer-readable medium of claim 8, wherein the pre-determined set of system variables includes a switch to initiate a tracking mechanism for components that execute in a computer system memory.
10. The computer-readable medium of claim 9, wherein the tracking mechanism is configured to monitor operations performed by the components that execute in the computer system memory.
11. The computer-readable medium of claim 1, wherein the software component is a device driver.
12. The computer-readable medium of claim 1, wherein automatically initiating the self-diagnostic procedure includes performing operations to monitor a use of resources associated with a system memory by one or more software components.
13. The computer-readable medium of claim 1, further comprising, upon a subsequent system crash, reporting results of the self-diagnostic procedure.
14. The computer-readable medium of claim 13, wherein the results of the self-diagnostic procedure include information to assist with the identification of a software component responsible for the system crash.
the memory manager being configured to receive the stop code from the boot loader, to initiate a self-diagnostic procedure corresponding to the stop code, and to report results associated with the self-diagnostic procedure.
16. The computer-readable medium of claim 15, wherein the crash driver is further configured to write the stop code to the location on non-volatile storage in association with additional information representing a state of memory at the time of the system crash.
17. The computer-readable medium of claim 16, wherein the stop code and the additional information are written to a dump file on the non-volatile storage.
18. The computer-readable medium of claim 17, wherein the location on the non-volatile storage comprises a pagefile.
19. The computer-readable medium of claim 15, wherein the self-diagnostic procedure includes setting system variables that identify a set of tracking operations to track the usage of system memory.
20. The computer-readable medium of claim 19, wherein the set of tracking operations are configured to maintain a table of allocations and deallocations of selected resources associated with the system memory.
21. The computer-readable medium of claim 19, wherein the set of tracking operations are configured to monitor functions performed by a software component associated with a computer system.
22. The computer-readable medium of claim 21, wherein the software component is a device driver, and wherein the set of tracking operations includes a driver verifier.
providing data obtained via the self-diagnostic procedure upon a subsequent crash.
24. The method of claim 23 wherein detecting that the system has previously crashed comprises locating information on disk.
25. The method of claim 24 wherein the information on disk corresponds to a dump file of selected system state information.
26. The method of claim 25 wherein locating information corresponding to the type of crash includes locating a stop code associated with the dump file.
27. The method of claim 23 wherein locating information corresponding to the type of crash includes locating a stop code.
28. The method of claim 23 wherein automatically initiating a self-diagnostic procedure includes maintaining at least one data structure to track allocated virtual memory.
29. The method of claim 23 wherein automatically initiating a self-diagnostic procedure includes maintaining at least one data structure to track locked pages.
30. The method of claim 23 wherein automatically initiating a self-diagnostic procedure includes maintaining at least one data structure to track usage of page table entries.
31. The method of claim 23 wherein automatically initiating a self-diagnostic procedure includes allocating memory bounded by memory marked as no access.
32. The method of claim 23 wherein automatically initiating a self-diagnostic procedure includes marking deallocated memory as no access.
Chow et al. 2005 Shredding Your Garbage: Reducing Data Lifetime Through Secure Deallocation.


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Study: 2013 Chicago School Closings Failed To Help Students
By Sarah Karp
May 22, 2018, 12:05 a.m. CT
Chicago closed a record 50 schools in 2013, affecting 11,000 children from those schools. Kayla Porter, 9, walks with her grandmother and mother to her new school on the South Side after the school Kayla had attended the previous school year was closed. AP Photos/M. Spencer Green
Despite Mayor Rahm Emanuel's promise that mass school closings in 2013 would lead to a "brighter future," Chicago students didn't benefit academically and on average their performance suffered, particularly in math, according to a University of Chicago Consortium on School Research study released on Tuesday.
The groundbreaking study goes on to report that for students and teachers, the transition was traumatic and chaotic.
Previous studies also have found that school closings hurt children. But this time, city and school district officials said they could mitigate the damage by investing $180 million in schools that took in children from underenrolled closed schools and with a logistics company to make the transition smooth.
The study is the first in-depth examination of the impact of the 50 school closings — the largest number closed at once in the United States. Some 11,000 students attended the closed schools, and another 13,000 students attended the schools that received them. All told, 95 schools buildings were packed up and moved.
Dashed Hope: How A Once Proud Chicago High School Hollowed Out
"Closing schools — even poorly performing ones — does not improve the outcome of displaced children, on average," the study concludes. "Closing under-enrolled schools may seem like a viable solution to policymakers who seek to address fiscal deficits and declining enrollment, but our findings shows that closing schools caused large disruptions without clear benefits for students."
Emanuel did not comment on the findings. CPS had said that closing the 50 schools would save $43 million annually and $437 million over time by not having to fix or maintain the shuttered buildings. But the school district has never provided any detailed information on whether those savings were or will be realized.
CPS' current Schools Chief Janice Jackson called what happened "unacceptable." But said the outcome will not deter her from closing schools in the future. At the time of the closings in 2013, Jackson was principal of a West Side high school.
"We acknowledge that it was imperfect," she said. "For me, I can focus on the learnings that came out of that."
After taking a five-year break from school closings, the Chicago Board of Education voted in February to shutter one elementary school and four high schools. Jackson is allowing most current students to stay until they graduate and she is providing extra support for students before and after they graduate.
Research predicted this outcome
Consortium researchers note that previous studies found school closings didn't help students academically unless they ended up in dramatically better schools or if the closures resulted in few disruptions. That didn't happen in 2013 in Chicago. They also said studies show test scores tend to decline in the year of the school closing, as they did in 2013 in Chicago.
Those previous studies found test scores recovered in subsequent years. But this study found that for the 11,000 students who moved from closed schools, math scores on average have yet to catch up four years after the closings, though reading scores did. Math scores declined by roughly two months; reading scores declined by about 1.5 months.
The new consortium study compared the performance of students in closed schools with others in poor-performing, high-poverty, underutilized schools in 2012-2013 that did not close. On average, these students, like all students in CPS, saw their test scores improve. But the study found students from closed schools would be doing better had their schools stayed open.
The study also found that student grade point averages declined slightly over time, especially for students in third through fifth grades in 2013. This is worrisome because grades are predictive of ultimately graduating high school, more so than test scores, the researchers said.
On a positive note, consortium researchers found no increase in absenteeism, mobility, or suspension rates among students from closed schools. However, they say these metrics could be affected by changes in policy, rather than in the behavior of students or the relationship of schools to students.
Staff and students felt disrespected
The study not only looked at test scores; it also included extensive interviews with affected students and staff at six schools. Emanuel and CPS leadership had pledged to make the receiving schools better than the ones they were closing. They would be repaired, repainted, provided libraries, science labs, and top-notch technology.
They also were all given Safe Passage workers to watch over students as they walk to and from schools. Students and staff point to those workers as one of the most beneficial change enacted.
But these interviews paint a damning picture of a chaotic process where even fundamental tasks were flubbed as CPS rushed to close and merge schools in just three months. CPS voted to close the schools in late May, 2013. Principals and staff told researchers that textbooks and instructional materials were lost in the move. And, when staff arrived in August to open the school year, some of the receiving schools were unclean and upgrades were unfinished.
"Ultimately, teachers and staff in the six schools interpreted these losses as a sign that the district did not respect staff or care about the students in these schools. As one teacher explained, 'CPS doesn't care. They just don't care, and it shows,'" according to the report.
As for the technology and new programming, staff appreciated the investment, but many of the schools were not able to sustain them because of budget cuts. Schools got new iPads, which were a hit with students and staff, but there was little training on how to use them for instructional purposes.
The year after the merger, teachers also reported a spike in "conflict and disorder," and students said there was more bullying and fights. Over time, it lessened but did not return to the levels before the the closing, according to the study.
It was not just staff and students from closed schools that were affected. The study found that students in the receiving schools also suffered. More than expected transferred out of the receiving schools in the year of the school mergers.
Also, the test scores of students in the receiving schools dropped in the first year, though they rebounded. Like the students from the closed schools, the receiving school students told researchers they mourned the loss of the culture and family feeling they had before the mergers.
Consortium researchers say they hope CPS officials take note of the study and incorporate the findings as the school district contemplates more closures. In the five years since the mass closures, student enrollment has continued to drop dramatically. Lead author Molly Gordon said she doesn't think Emanuel or other officials meant for there to be negative outcomes.
"Policymakers make decisions and they hope for a specific outcome or result," she said. "But not all the intended benefits play out in reality."
Sarah Karp covers education for WBEZ. Follow her @WBEZeducation and @sskedreporter.
Will Chicago Close Another 50 Schools?
Nov. 25, 2017 read more
Chicago High Schools Compete Against Each Other — For Students
Chicago Proposes First Round Of School Closings Since 2013
Dec. 1, 2017 read more


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Home AmLaw Recognizes Amber Rogers as a Trailblazer
AmLaw Recognizes Amber Rogers as a Trailblazer
By Hunton Andrews Kurth LLP on October 4, 2021
HuntonAK labor and employment partner, Amber Rogers was named to The American Lawyers inaugural list of Trailblazers South 2021.
Trailblazers South spotlights attorneys in Texas and other southern and eastern states who are considered "agents of change" and "have moved the needle in the legal industry."
Amber was recently named among Bloomberg Law's 40 Under 40, 2021, an 2021 Employment Rising Star 2021 by Law360, recognized as a 2020 Women in Business honoree by Dallas Business Journal, and Named among 2020 Women Worth Watching by Profiles in Diversity Journal.
Amber's practice assists clients with traditional labor relations and litigation, employment advice and counseling, and complex employment litigation. She also serves on the firm's Executive Committee, as the hiring partner for the Dallas office, and as co-chair of the diversity and inclusion committee for the Dallas office.
For more information read the firm press release. Amber's feature can be read here.
Tags: Amber Rogers, American Lawyer
Amber Rogers Selected as 2023 Texas 100