From: Peter Maydell <peter.maydell@linaro.org>
To: Kevin Wolf <kwolf@redhat.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Fam Zheng <famz@redhat.com>,
QEMU Developers <qemu-devel@nongnu.org>,
Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [Qemu-devel] [PULL for-2.5 2/4] block: Don't wait serialising for non-COR read requests
Date: Tue, 8 Dec 2015 14:15:22 +0000 [thread overview]
Message-ID: <CAFEAcA_HH_nLKt2bMs0q7Lin6jLVpvMkK0REHuY-H+cdfeyPpw@mail.gmail.com> (raw)
In-Reply-To: <20151208134522.GE5071@noname.str.redhat.com>
On 8 December 2015 at 13:45, Kevin Wolf <kwolf@redhat.com> wrote:
> Coroutines don't save the FPU state, so you're not supposed to use
> floating point operations inside coroutines. That the compiler spills
> some integer value into a floating point register is a bit nasty...
The compiler will happily use FP registers even for apparently
integer code if it thinks that is a better way to do it (eg on
some CPUs doing memcpy and other kinds of block data move may
go faster via the FPU registers, or it might be faster to spill
an integer register into an FP register rather than spilling it
to memory). As I see you've already determined, it's the
job of setjmp/longjmp to make sure that everything is saved
and restored correctly, fp or otherwise...
thanks
-- PMM
next prev parent reply other threads:[~2015-12-08 14:15 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-03 4:59 [Qemu-devel] [PULL for-2.5 0/4] Block patches Stefan Hajnoczi
2015-12-03 4:59 ` [Qemu-devel] [PULL for-2.5 1/4] iothread: include id in thread name Stefan Hajnoczi
2015-12-07 9:58 ` Cornelia Huck
2015-12-03 5:00 ` [Qemu-devel] [PULL for-2.5 2/4] block: Don't wait serialising for non-COR read requests Stefan Hajnoczi
2015-12-07 10:02 ` Cornelia Huck
2015-12-07 16:42 ` Cornelia Huck
2015-12-08 2:08 ` Fam Zheng
2015-12-08 9:59 ` Kevin Wolf
2015-12-08 12:00 ` Cornelia Huck
2015-12-08 12:30 ` Christian Borntraeger
2015-12-08 13:28 ` Christian Borntraeger
2015-12-08 13:45 ` Kevin Wolf
2015-12-08 13:58 ` Christian Borntraeger
2015-12-08 14:03 ` Christian Borntraeger
2015-12-08 14:10 ` Kevin Wolf
2015-12-08 14:24 ` Christian Borntraeger
2015-12-08 14:38 ` Cornelia Huck
2015-12-08 14:15 ` Peter Maydell [this message]
2015-12-03 5:00 ` [Qemu-devel] [PULL for-2.5 3/4] iotests: Add "add_drive_raw" method Stefan Hajnoczi
2015-12-03 5:00 ` [Qemu-devel] [PULL for-2.5 4/4] iotests: Add regresion test case for write notifier assertion failure Stefan Hajnoczi
2015-12-03 11:53 ` [Qemu-devel] [PULL for-2.5 0/4] Block patches Peter Maydell
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