From: "H.J. Lu" <hjl.tools@gmail.com>
To: Rich Felker <dalias@libc.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Andrew Pinski <apinski@cavium.com>,
linux-arm-kernel@lists.infradead.org,
LKML <linux-kernel@vger.kernel.org>,
Andrew Pinski <pinskia@gmail.com>,
musl@lists.openwall.com,
GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCHv3 00/24] ILP32 support in ARM64
Date: Wed, 11 Feb 2015 10:33:32 -0800 [thread overview]
Message-ID: <CAMe9rOqX-VpjZ+E-JCusk+e4Kpw1V1tsFq1Kjtai5DR9saKLaA@mail.gmail.com> (raw)
In-Reply-To: <20150210181302.GA23886@brightrain.aerifal.cx>
On Tue, Feb 10, 2015 at 10:13 AM, Rich Felker <dalias@libc.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.
next prev parent reply other threads:[~2015-02-11 18:33 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20141002155217.GH32147@e104818-lin.cambridge.arm.com>
2015-02-10 18:13 ` Rich Felker
2015-02-11 17:39 ` Catalin Marinas
2015-02-11 19:05 ` Szabolcs Nagy
2015-02-11 19:22 ` [musl] " H.J. Lu
2015-02-11 19:50 ` arnd
2015-02-11 20:12 ` Rich Felker
2015-02-11 20:47 ` Jens Gustedt
2015-02-11 21:02 ` arnd
2015-02-11 21:09 ` arnd
2015-02-11 21:37 ` [musl] " Rich Felker
2015-02-16 17:20 ` Arnd Bergmann
2015-02-16 17:51 ` [musl] " Rich Felker
2015-02-16 19:38 ` Arnd Bergmann
2015-02-12 8:12 ` Szabolcs Nagy
2015-02-12 17:07 ` Catalin Marinas
2015-02-11 19:21 ` Rich Felker
2015-02-12 18:17 ` Catalin Marinas
2015-02-12 18:59 ` arnd
2015-02-13 13:33 ` Catalin Marinas
2015-02-13 16:30 ` Rich Felker
2015-02-13 17:33 ` Catalin Marinas
2015-02-13 18:37 ` Rich Felker
2015-02-16 14:40 ` Arnd Bergmann
2015-02-16 15:38 ` Rich Felker
2015-02-16 16:54 ` Arnd Bergmann
2015-02-11 18:33 ` H.J. Lu [this message]
2015-02-11 19:02 ` Rich Felker
2015-02-11 19:16 ` H.J. Lu
2015-02-11 19:25 ` Rich Felker
2015-02-11 19:34 ` H.J. Lu
2015-02-11 19:47 ` Rich Felker
2015-02-11 19:57 ` H.J. Lu
2015-02-11 20:15 ` Andy Lutomirski
2015-02-12 15:50 ` Catalin Marinas
2015-02-12 16:13 ` Rich Felker
2015-02-12 16:30 ` H.J. Lu
2015-02-12 17:00 ` Rich Felker
2015-02-11 21:41 ` Joseph Myers
2015-02-11 19:04 ` Josiah Worcester
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