Date: Mon, 16 Nov 2015 10:16:35 +0000
From: Joseph Myers <joseph@codesourcery.com>
To: Chris Metcalf <cmetcalf@ezchip.com>
CC: Arnd Bergmann <arnd@arndb.de>, <linux-arm-kernel@lists.infradead.org>,
        <bamvor.zhangjian@huawei.com>, Andrew Pinski <pinskia@gmail.com>,
        "Kapoor, Prasun" <Prasun.Kapoor@caviumnetworks.com>,
        Andreas Schwab <schwab@suse.de>,
        Nathan Lynch <Nathan_Lynch@mentor.com>,
        LKML <linux-kernel@vger.kernel.org>, Alexander Graf <agraf@suse.de>,
        Alexey Klimov <klimov.linux@gmail.com>, <broonie@kernel.org>,
        Yury Norov <ynorov@caviumnetworks.com>,
        Andrew Pinski <apinski@cavium.com>,
        David Daney <ddaney.cavm@gmail.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Jan Dakinevich <jan.dakinevich@gmail.com>,
        Philipp Tomsich <philipp.tomsich@theobroma-systems.com>,
        Andrey Konovalov <andrey.konovalov@linaro.org>,
        <christoph.muellner@theobroma-systems.com>,
        Mike Frysinger <vapier@gentoo.org>, Paul Eggert <eggert@cs.ucla.edu>,
        Rich Felker <dalias@libc.org>
Subject: Re: [PATCH v6 13/17] arm64:ilp32: add sys_ilp32.c and a separate
 table (in entry.S) to use it
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On Sun, 15 Nov 2015, Chris Metcalf wrote:

> I've added Rich, Paul, Joseph, and Mike to the cc's as they are probably 
> a good subset of libc-alpha to help comment on these issues.  My sense 
> is that right now, it wouldn't be possible to add a 32-bit architecture 
> with a non-32-bit default for _FILE_OFFSET_BITS.  And, obviously, this 
> is why, when I added the tilegx32 APIs to glibc in 2011, I needed to 
> provide _FILE_OFFSET_BITS=32 support.

x32 uses 64-bit off_t only.  That's not a problem; the problems are 
tv_nsec not of type long, a bug we should avoid for all new ports (padding 
on tv_nsec is fine; treating that padding as a significant high part of a 
64-bit value on input to glibc / kernel interfaces isn't), and maybe some 
other types being 64-bit unnecessarily, although as far as I know the 
suggested issues there 
<https://sourceware.org/bugzilla/show_bug.cgi?id=16438> are all 
theoretical.

It's true that we don't have a very clear notion of what "wordsize-64" 
sysdeps directories mean in glibc for cases such as x32.  See 
<https://sourceware.org/bugzilla/show_bug.cgi?id=14116>.

-- 
Joseph S. Myers
joseph@codesourcery.com
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