From: Aurelien Jarno <aurelien@aurel32.net>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>,
Leon Alrae <leon.alrae@imgtec.com>,
QEMU Developers <qemu-devel@nongnu.org>,
Richard Henderson <rth@twiddle.net>
Subject: Re: [Qemu-devel] [PATCH 2/2] tcg/i386: Reserve register for guest_base if a segment isn't available
Date: Fri, 17 Jul 2015 17:56:26 +0200 [thread overview]
Message-ID: <20150717155625.GK11361@aurel32.net> (raw)
In-Reply-To: <55A91F87.6030300@redhat.com>
On 2015-07-17 17:30, Paolo Bonzini wrote:
>
>
> On 17/07/2015 03:33, Peter Maydell wrote:
> > On 16 July 2015 at 22:25, Richard Henderson <rth@twiddle.net> wrote:
> > > This saves 2 insns and 10 bytes from the implementation of
> > > each memory operation.
> >
> > Do we have an idea of which platforms/configs don't let
> > us have a segment register for guest_base?
>
> Everything non-Linux I think, which for user-mode emulation means bsd-user.
Linux might also not allow to use a segment register if the prctl call
with ARCH_SET_GS fails. OTOH I have no idea why it can fail, but we
actually check that it doesn't fail before using %gs.
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://www.aurel32.net
next prev parent reply other threads:[~2015-07-17 15:56 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-16 21:25 [Qemu-devel] [PATCH for-2.4 0/2] tcg/i386 address zero-extension Richard Henderson
2015-07-16 21:25 ` [Qemu-devel] [PATCH 1/2] tcg/i386: Extend addresses for 32-bit guests Richard Henderson
2015-07-17 10:18 ` Aurelien Jarno
2015-07-16 21:25 ` [Qemu-devel] [PATCH 2/2] tcg/i386: Reserve register for guest_base if a segment isn't available Richard Henderson
2015-07-17 1:33 ` Peter Maydell
2015-07-17 6:02 ` Richard Henderson
2015-07-17 15:30 ` Paolo Bonzini
2015-07-17 15:56 ` Aurelien Jarno [this message]
2015-07-17 10:18 ` Aurelien Jarno
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