linux-kernel - RE: [PATCH] io_thread/x86: don't reset 'cs', 'ss', 'ds' and 'es' registers for io

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Date:   Thu, 6 May 2021 09:53:53 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Andy Lutomirski' <luto@...nel.org>,
        'Simon Marchi' <simon.marchi@...ymtl.ca>
CC:     'Stefan Metzmacher' <metze@...ba.org>,
        'Borislav Petkov' <bp@...en8.de>,
        'Peter Zijlstra' <peterz@...radead.org>,
        'Linus Torvalds' <torvalds@...ux-foundation.org>,
        'Thomas Gleixner' <tglx@...utronix.de>,
        'Jens Axboe' <axboe@...nel.dk>,
        'Linux Kernel Mailing List' <linux-kernel@...r.kernel.org>,
        'io-uring' <io-uring@...r.kernel.org>,
        "'the arch/x86 maintainers'" <x86@...nel.org>,
        "'linux-toolchains@...r.kernel.org'" 
        <linux-toolchains@...r.kernel.org>
Subject: RE: [PATCH] io_thread/x86: don't reset 'cs', 'ss', 'ds' and 'es'
 registers for io_threads

> > (To avoid confusion, this is not a universal property of Linux.  arm64
> > and arm32 tasks on an arm64 Linux host are different and cannot
> > arbitrarily switch modes.)
> 
> Although there are patches lurking to change that.
> (not from me).

Actually they may be just to allow 64bit tasks make 32bit system calls.
The code is almost certainly still 54bit.

	David

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