Date: Mon, 16 Nov 2015 11:12:08 +0000
From: Joseph Myers <joseph@codesourcery.com>
To: Arnd Bergmann <arnd@arndb.de>
CC: Chris Metcalf <cmetcalf@ezchip.com>,
        <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 Mon, 16 Nov 2015, Arnd Bergmann wrote:

> Let's not get into the tv_nsec discussion today, that is not thankfully
> not relevant for arm64 any more at this point. The system call ABI for
> arm64/ilp32 is now the same as for any other 32-bit architecture using
> the generic ABI, the question we're trying to solve here is only whether it
> is ok for new 32-bit glibc ports to only offer a 64-bit off_t as the kernel
> currently does (using __kernel_loff_t) or if we still need to support the
> _FILE_OFFSET_BITS=32 case.
> 
> If I got you right, we can use 64-bit off_t now, so we just need someone
> to figure out how to make that the default in glibc for new architectures
> while keeping the existing 32-bit architectures unchanged.

It would be an entirely new combination.  Presumably such a port would 
want the "function X is an alias of function Y" aspects of wordsize-64 
directories (where that relates to off_t, struct stat etc. as opposed to 
long and long long), and the "registers are 64-bit so 64-bit operations 
are efficient" aspects, but not all the "64-bit syscall interface" 
aspects, so someone would need to review wordsize-64 sysdeps files and 
figure out what is or is not relevant to this port.

-- 
Joseph S. Myers
joseph@codesourcery.com
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