qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PULL for-2.5 2/4] block: Don't wait serialising for no


From: Peter Maydell
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

On 8 December 2015 at 13:45, Kevin Wolf <address@hidden> 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



reply via email to

[Prev in Thread] Current Thread [Next in Thread]