On 8/27/24 22:49, Charlie Jenkins wrote: > Some applications rely on placing data in free bits addresses allocated > by mmap. Various architectures (eg. x86, arm64, powerpc) restrict the > address returned by mmap to be less than the maximum address space, > unless the hint address is greater than this value. Which applications are these, btw? Is this the same crowd as the folks who are using the address tagging features like X86_FEATURE_LAM? Even if they are different, I also wonder if a per-mmap() thing MAP_BELOW_HINT is really what we want. Or should the applications you're trying to service here use a similar mechanism to how LAM affects the *whole* address space as opposed to an individual mmap().
