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Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff

From: Paolo Bonzini
Subject: Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff
Date: Fri, 26 Jul 2013 11:19:19 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7

Il 26/07/2013 11:08, Alex Bligh ha scritto:
> --On 26 July 2013 10:43:45 +0200 Stefan Hajnoczi <address@hidden>
> wrote:
>> block.c and block/qed.c use vm_clock because block drivers should not do
>> guest I/O while the vm is stopped.  This is especially true during live
>> migration where it's important to hand off the image file from the
>> source host to the destination host with good cache consistency.  The
>> source host is not allowed to modify the image file anymore once the
>> destination host has resumed the guest.
>> Block jobs use rt_clock because they aren't considered guest I/O.
> That's going to be 'interesting' if qemu-img uses a block driver that
> uses a timer, as I don't think the vm timer is running when qemu-img
> is running.

Yes, it is, see stubs/cpu-get-clock.c:

#include "qemu-common.h"
#include "qemu/timer.h"

int64_t cpu_get_clock(void)
    return get_clock_realtime();

vm_clock becomes a synonym of rt_clock basically.


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