Date: Tue, 29 Mar 2016 20:15:10 +0000
From: Joseph Myers <joseph@codesourcery.com>
To: Arnd Bergmann <arnd@arndb.de>
CC: "Zhangjian (Bamvor)" <bamvor.zhangjian@huawei.com>,
        Yury Norov <ynorov@caviumnetworks.com>,
        <linux-arm-kernel@lists.infradead.org>,
        Andreas Schwab <schwab@suse.de>, <young.liuyang@huawei.com>,
        <pinskia@gmail.com>, <Prasun.Kapoor@caviumnetworks.com>,
        <catalin.marinas@arm.com>, <broonie@kernel.org>,
        "jijun (D)" <jijun2@huawei.com>, <heiko.carstens@de.ibm.com>,
        <linux-kernel@vger.kernel.org>, <agraf@suse.de>,
        <klimov.linux@gmail.com>, <jan.dakinevich@gmail.com>,
        <gaoyongliang@huawei.com>, <schwidefsky@de.ibm.com>,
        <Nathan_Lynch@mentor.com>,
        Bamvor Zhang Jian <bamvor.zhangjian@linaro.org>,
        <christoph.muellner@theobroma-systems.com>
Subject: Re: [RFC5 PATCH v6 00/21] ILP32 for ARM64
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On Tue, 29 Mar 2016, Arnd Bergmann wrote:

> How do we do it then? Should we just define __USE_FILE_OFFSET64
> unconditionally for all new 32-bit architectures and leave the
> code dealing with 32-bit off_t/ino_t in place but unreachable, to
> minimize the differences?

Defining __USE_FILE_OFFSET64 unconditionally would prevent glibc from 
building (see: how the patches a while back prototyping changing the 
default had to disable the change when glibc itself is built).  A change 
in the default, though desired (someone needs to pick up those patches 
together with the analysis done of possible impact on distributions), 
should not be tied to a new port, and would need to be discussed 
thoroughly on libc-alpha.

> Or should all the obsolete types be defined the same way as their
> replacements so we have 64-bit __OFF_T_TYPE/__INO_T_TYPE
> and use the same binary implementation regardless of FILE_OFFSET_BITS?

I think so (along with using wordsize-64 sysdeps directories as far as 
possible, like x32 does).  But design questions for a glibc port really 
belong on libc-alpha to get any sort of community consensus.

-- 
Joseph S. Myers
joseph@codesourcery.com