I agree that sbrk&#x2F;brk are nearly deprecated.  But not all allocators I studied use mprotect or mmap.  Most reference material (old OS books &amp; blogs) still refer to sbrk&#x2F;brk and&#x2F;or malloc when discussing reference counters or garbage collectors.  And Linux has a nice gotcha (see the Linux notes here[1]) in its implementation of the sys_brk syscall.  It matches neither of the interfaces described for sbrk or brk exactly that most people are familiar with.<p>For me, however, I have a personal goal to show how to implement the basic newlib porting requirements [2].<p>[1] <a href="http:&#x2F;&#x2F;linux.die.net&#x2F;man&#x2F;2&#x2F;brk" rel="nofollow">http:&#x2F;&#x2F;linux.die.net&#x2F;man&#x2F;2&#x2F;brk</a><p>[2] <a href="http:&#x2F;&#x2F;wiki.osdev.org&#x2F;Porting_Newlib" rel="nofollow">http:&#x2F;&#x2F;wiki.osdev.org&#x2F;Porting_Newlib</a>