Messages in this thread | | | Date | Mon, 16 Mar 2015 10:16:37 -0400 | From | Christopher Covington <> | Subject | Re: [PATCH] arm64: Enable CONFIG_COMPAT also for 64k page size |
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Hi,
On 03/11/2015 08:47 AM, Arnd Bergmann wrote: > On Wednesday 11 March 2015 06:24:16 Alexander Graf wrote: >> So after recompiling all of the distribution with newer binutils we now >> have an openSUSE Factory tree that has 64k aligned 32bit binaries. >> >> Unfortunately however, the 32bit glibc has a bogus mmap() implementation >> that hard codes 4k page size. >> >> With the patch below applied to glibc, I can successfully run 32bit user >> space on Seattle with 64k PAGE_SIZE though. So I guess we'll need to fix >> up glibc next. >> >> Do you know of anyone who's fluent enough in 32bit ARM assembly to >> convert the hard coded assumptions in there to instead use a variable >> that takes the actual host page size into account? > > I believe this is a kernel bug, and the kernel API for 32-bit emulation > should always take the pgoff argument in 4KB units instead of PAGE_SIZE > units, see the implementation of sys_mmap2 in > arch/powerpc/kernel/sys_ppc32.c. > > All user space programs that call mmap2 still need to make sure that > their arguments are PAGE_SIZE aligned, but the libc need not care > about this here.
What is the correct behavior for /proc/pid/pagemap, /proc/kpagecount, and /proc/kpageflags for a AArch32 process running on an AArch64 kernel with non-4K translation granule? Actual page frame number or units-of-4K frame number?
Thanks, Chris
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