Date: Wed, 11 Feb 2015 10:33:32 -0800 From: "H.J. Lu" <hjl.tools@...il.com> To: Rich Felker <dalias@...c.org> Cc: Catalin Marinas <catalin.marinas@....com>, Andrew Pinski <apinski@...ium.com>, linux-arm-kernel@...ts.infradead.org, LKML <linux-kernel@...r.kernel.org>, Andrew Pinski <pinskia@...il.com>, musl@...ts.openwall.com, GNU C Library <libc-alpha@...rceware.org> Subject: Re: [PATCHv3 00/24] ILP32 support in ARM64 On Tue, Feb 10, 2015 at 10:13 AM, Rich Felker <dalias@...c.org> wrote: > On Thu, 2 Oct 2014 at 16:52:18 +0100, Catalin Marinas wrote: >> On Wed, Sep 03, 2014 at 10:18:54PM +0100, Andrew Pinski wrote: >> > New version with all of the requested changes. Updated to the >> > latest sources. >> > >> > Notable changes from the previous versions: >> > VDSO code has been factored out to be easier to understand and >> > easier to maintain. >> > Move the config option to the last thing that gets added. >> > Added some extra COMPAT_* macros for core dumping for easier usage. >> >> Apart from a few comments I've made, I would also like to see non-empty >> commit logs and long line wrapping (both in commit logs and >> Documentation/). Otherwise, the patches look fine. >> >> So what are the next steps? Are the glibc folk ok with the ILP32 Linux >> ABI? On the kernel side, what I would like to see: > > I don't know if this has been discussed on libc-alpha yet or not, but > I think we need to open a discussion of how it relates to open glibc > bug #16437, which presently applies only to x32 (ILP32 ABI on x86_64): > > https://sourceware.org/bugzilla/show_bug.cgi?id=16437 Please leave x32 out of this discussion. I have resolved this bug as WONTFIX. > While most of the other type changes proposed (I'm looking at > https://lkml.org/lkml/2014/9/3/719) are permissible and simply > ugly/undesirable, defining struct timespec with tv_nsec having any > type other than long conflicts with the requirements of C11 and POSIX, > and WG14 is unlikely to be interested in changing the C language > because the Linux kernel has the wrong type in timespec. > > Note that on aarch64 ILP32, the consequences of not fixing this right > away will be much worse than on x32, since aarch64 (at least as I > understand it) supports big endian where it's not just a matter of > sign-extending the value from userspace and ignoring the padding, but > rather changing the offset of the tv_nsec member. > > Working around the discrepencies in userspace IS possible, but ugly. > We do it in musl libc for x32 right now -- see: > > http://git.musl-libc.org/cgit/musl/tree/arch/x32/syscall_arch.h?id=v1.1.6 > http://git.musl-libc.org/cgit/musl/tree/arch/x32/src/syscall_cp_fixup.c?id=v1.1.6 You are free to do what you feel appropriate. I have no plans to change x32 on this in glibc at this moment. > I imagine the workarounds in glibc might need to be considerably more > widespread and uglier. > > Whatever happens on the kernel side, this needs to be coordinated with > userspace (glibc, etc.) properly so that the type error (glibc bug > 16437) is not propagated into a new target that we actually want > people to use. I'd really like it if other undesirable type changes > could be cleaned up too, but perhaps that's too much to ask from the > kernel side. > > Rich -- H.J.
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.