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Date: Tue, 25 Jun 2013 06:56:10 -0700
From: Richard Henderson <rth@twiddle.net>
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Subject: Re: [Qemu-devel] [PATCH] linux-user: Move cpu_clone_regs() and
 cpu_set_tls() into linux-user
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Jia Liu <proljc@gmail.com>, patches@linaro.org, Riku Voipio <riku.voipio@iki.fi>, Alexander Graf <agraf@suse.de>, qemu-devel@nongnu.org, Blue Swirl <blauwirbel@gmail.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Guan Xuetao <gxt@mprc.pku.edu.cn>, =?ISO-8859-1?Q?Andreas_F=E4rber?= <afaerber@suse.de>, Aurelien Jarno <aurelien@aurel32.net>

On 06/25/2013 03:35 AM, Peter Maydell wrote:
> (and maybe even actually get all targets
> up to having NPTL enabled, since it's mostly just implementing
> the two functions being moved here for x86, sparc, openrisc.

There's far more to it than that for x86.  You've got to add
support for all of the locked arithmetic instructions.

We currently have several hacks for atomic operations in
linux-user, usually involving some escape into the cpu loop that
pauses the other threads.  This as opposed to assuming some
atomic support on behalf of the host...

It's a mess.


r~