On Wednesday 22 August 2012, Catalin Marinas wrote:

But what's more important - moving this wrapper to glibc causes issues
with the page size. We support both 4KB and 64KB pages on 64-bit systems
(the latter without compat support). The kernel is in a better position
to do the shift by a compile-time constant. Glibc would need to enquire
the actual page size to do the shift before calling sys_mmap_pgoff. If
we assume in glibc that the shift is always 12, we need another wrapper
in the kernel anyway for 64KB page configuration. So passing the offset
in bytes worked best for us.

Right, the kernel interface should really be independent of the page
size, as sys_mmap2 normally is, and sys_mmap2 is not provided here.

	Arnd