From: Catalin Marinas <catalin.marinas@arm.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: "H.J. Lu" <hjl.tools@gmail.com>, Rich Felker <dalias@libc.org>,
GNU C Library <libc-alpha@sourceware.org>,
Andrew Pinski <pinskia@gmail.com>,
musl@lists.openwall.com, LKML <linux-kernel@vger.kernel.org>,
Andrew Pinski <apinski@cavium.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCHv3 00/24] ILP32 support in ARM64
Date: Thu, 12 Feb 2015 15:50:24 +0000 [thread overview]
Message-ID: <20150212155023.GA25491@e104818-lin.cambridge.arm.com> (raw)
In-Reply-To: <54DBB87C.5060901@amacapital.net>
On Wed, Feb 11, 2015 at 12:15:56PM -0800, Andy Lutomirski wrote:
> On 02/11/2015 11:57 AM, H.J. Lu wrote:
> >>>>trivially satisfied if you consider x32 and x86_64 separate
> >>>>compilation environments, but it's not related to the core issue: that
> >>>>the definition of timespec violates core (not obscure) requirements of
> >>>>both POSIX and C11. At the time you were probably unaware of the C11
> >>>>requirement. Note that it's a LOT harder to effect change in the C
> >>>>standard, so even if the Austin Group would be amenable to changing
> >>>>the requirement for timespec to allow something like nseconds_t,
> >>>>getting WG14 to make this change to work around a Linux/glibc mistake
> >>>>does not sound practical.
> >>>
> >>>That is very unfortunate. I consider it is too late for x32 to change.
> >>
> >>Why? It's hardly an incompatible ABI change, as long as the
> >>kernel/libc fills the upper bits (for old programs that read them
> >>based on the old headers) when structs are read from the kernel to the
> >>application, and ignores the upper bits (potentially set or left
> >>uninitialized by the application) when strings are passed from
> >>userspace to the kernel. Newly built apps using the struct definition
> >>with 32-bit tv_nsec would need new libc to ensure that the high bits
> >>aren't interpreted, but this could be handled by symbol versioning.
> >>
> >
> >We have considered this option. But since kernel wouldn't change
> >tv_nsec/tv_usec handling just for x32, it wasn't selected.
>
> Did anyone *ask* the kernel people (e.g. hpa)?
It seems so:
https://lkml.org/lkml/2011/8/31/244
Couple of more replies from hpa:
https://lkml.org/lkml/2011/8/31/261
https://lkml.org/lkml/2012/2/8/408
It looks like hpa was going to talk the POSIX committee but I don't know
what the conclusion was and didn't follow the thread (at the time I
wasn't interested in ARM ILP32).
--
Catalin
next prev parent reply other threads:[~2015-02-12 15:50 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
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 [this message]
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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