AMD responds to Linux kernel maintainer's rejection of AMDGPU patch
Coming from the FreeBSD perspective, I would freaking <i>LOVE</i> it if some drivers had a HAL (or, really, OSAL).   Instead, for the vendors that cannot allocate the resources to properly support FreeBSD, we have a linux kernel compat shim that tries to translate from the linux kernel apis to FreeBSD ones.  This is much harder to deal with than a HAL because it makes it even harder than a HAL to reason about the code.<p>One recent example is that I was debugging a rogue DMA issue in a driver that uses the linux kpi shims.  I wanted to use the Intel DMAR to try to catch the DMA, but because of the use of linux shims, the driver would not work at all with the DMAR.   We had to improve the linux kpi shims to do busdma, rather than just use pmap_kextrect() to convert kernel virtual to physical addresses (and this was a hack, because there is a gigantic imedence mismatch between dma_map_single and busdma).  And, as soon as we had the driver working with the DMAR, we caught the rogue DMA.<p>Weeks of my time could have been saved if, instead of writing to Linux, the vendor driver had included a full hal that supported busdma.  Instead, they wrote to the linux kpi.<p>And I fully blame the Linux kernel maintainers for this.  They&#x27;re on top of the world and can dictate to hardware vendors to remove their portability shims.  Meanwhile, other OS projects get the dregs.