From: "Michael S. Tsirkin" <mst@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Blue Swirl <blauwirbel@gmail.com>, qemu-devel@nongnu.org
Subject: [Qemu-devel] Re: [PATCH v2 2/2] get rid of hostregs_helper.h
Date: Thu, 25 Feb 2010 15:04:28 +0200 [thread overview]
Message-ID: <20100225130427.GA10660@redhat.com> (raw)
In-Reply-To: <4B867230.60708@redhat.com>
On Thu, Feb 25, 2010 at 01:50:56PM +0100, Paolo Bonzini wrote:
> On 02/25/2010 12:40 PM, Michael S. Tsirkin wrote:
>> On Thu, Feb 18, 2010 at 11:28:14PM +0200, Blue Swirl wrote:
>>>> /* restore global registers */
>>>> -#include "hostregs_helper.h"
>>>> + asm("");
>>>> + env = (void *) saved_env_reg;
>>>>
>>
>> Is this sufficient?
>> I see __asm__ __volatile__("": : :"memory") in virtio.
>> Is memory clobber implied? What about volatile?
>
> All asms without colons ("old-style") are volatile. Clobbering memory
> is not necessary since we are only caring about blocking assignments of
> "env", which is by definition in a register
Then I think you should add that as a clobber. Otherwise what prevents the
compiler from reordering this asm wrt assignments?
> (hostregs_helper.h wasn't
> clobbering memory either).
Maybe it was buggy :)
> Paolo
next prev parent reply other threads:[~2010-02-25 13:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-10 23:26 [Qemu-devel] [PATCH 0/2] simplify global register save/restore Paolo Bonzini
2010-02-10 23:26 ` [Qemu-devel] [PATCH 1/2] remove dead m68k global register definitions Paolo Bonzini
2010-02-10 23:26 ` [Qemu-devel] [PATCH 2/2] get rid of hostregs_helper.h Paolo Bonzini
2010-02-18 19:07 ` Blue Swirl
2010-02-18 20:25 ` [Qemu-devel] [PATCH v2 1/2] remove dead m68k definitions Paolo Bonzini
2010-02-18 20:25 ` [Qemu-devel] [PATCH v2 2/2] get rid of hostregs_helper.h Paolo Bonzini
2010-02-18 21:28 ` [Qemu-devel] " Blue Swirl
2010-02-25 11:40 ` Michael S. Tsirkin
2010-02-25 12:50 ` Paolo Bonzini
2010-02-25 13:04 ` Michael S. Tsirkin [this message]
2010-02-25 13:11 ` Paolo Bonzini
2010-02-13 17:58 ` [Qemu-devel] [PATCH 0/2] simplify global register save/restore Blue Swirl
2010-02-13 20:26 ` [Qemu-devel] " Paolo Bonzini
2010-02-13 20:57 ` Blue Swirl
2010-02-13 20:58 ` Paolo Bonzini
2010-02-26 11:30 ` [Qemu-devel] " Paul Brook
2010-02-26 13:05 ` Paolo Bonzini
2010-02-26 18:32 ` Paul Brook
2010-03-01 12:30 ` Paolo Bonzini
2010-03-01 14:02 ` Paul Brook
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