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Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen
From: |
Avi Kivity |
Subject: |
Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen |
Date: |
Tue, 24 Jan 2012 13:10:39 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:9.0) Gecko/20111222 Thunderbird/9.0 |
On 01/23/2012 07:18 PM, Anthony Liguori wrote:
> Generally speaking, RAM is an independent device in most useful cases.
Can you give examples? Do you mean a subdevice with composition, or a
really independent device?
> Onboard RAM is a very special case because it's extremely unusual.
What's unusual (or even extremely unusual) about it? I don't see a
difference between a few billion bits of state and, say, the few bits of
state in an RTC device.
> But since some video cards can make use of dedicated external RAM, I
> don't think any video card really depends on initial RAM state.
>
> What's most likely here is that the VGA BIOS of a Cirrus card sets an
> initial RAM state during device initialization.
Yes, that's likely. DRAMs aren't reset and some state survives even a
short power off.
>
> We really should view RAM as just another device so I don't like the
> idea of propagating a global concept of "when RAM is restored" because
> that treats it specially compared to other devices.
Agree. In fact the first step has been taken as now creating a RAM
region with memory_region_init_ram() doesn't register it for migration.
The next step would be a VMSTATE_RAM() to make it part of the containing
device.
> But viewing RAM as just another device, having Xen only restore a
> subset of devices should be a reasonable thing to do moving forward.
> The main problem here I believe is that we have part of the VGA Bios
> functionality in the hardware emulation.
Doesn't the main BIOS clear the screen first thing at boot? Not even
sure the reset is needed.
--
error compiling committee.c: too many arguments to function
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, (continued)
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Jan Kiszka, 2012/01/23
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Anthony Liguori, 2012/01/23
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Gerd Hoffmann, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Avi Kivity, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Stefano Stabellini, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Avi Kivity, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Anthony Liguori, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Avi Kivity, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Anthony Liguori, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Avi Kivity, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen,
Avi Kivity <=
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Paolo Bonzini, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Avi Kivity, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Paolo Bonzini, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Avi Kivity, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Stefano Stabellini, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Anthony Liguori, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Anthony Liguori, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Avi Kivity, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Anthony Liguori, 2012/01/24
- Re: [Qemu-devel] [PATCH v4 0/6] save/restore on Xen, Anthony Liguori, 2012/01/23