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Re: [Qemu-devel] [PATCH for-1.6 0/2] future proof rom loading for cross
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] [PATCH for-1.6 0/2] future proof rom loading for cross versiom migration |
Date: |
Mon, 12 Aug 2013 08:57:11 -0500 |
User-agent: |
Notmuch/0.15.2+202~g0c4b8aa (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) |
"Michael S. Tsirkin" <address@hidden> writes:
> ROM files that are put in FW CFG are copied to guest ram, by BIOS, but
> they are not backed by RAM so they don't get migrated.
>
> Each time we'll change at least two bytes in such a ROM this will break
> cross-version migration: since we can migrate after BIOS has read the first
> byte but before it has read the second one, getting an inconsistent state.
>
> This patchset makes QEMU future-proof against such changes.
>
> Naturally, this only helps for -M 1.6 and up, older machine types
> will still have the cross-version migration bug.
>
> I think this should be applied for 1.6, this way we won't
> have this problem from 1.7 and on.
This is not for 1.6. It's far too late to make a change like this.
Regards,
Anthony Liguori
>
> Michael S. Tsirkin (2):
> memory: export target page size
> loader: put FW CFG ROM files into RAM
>
> exec.c | 2 ++
> hw/core/loader.c | 54
> ++++++++++++++++++++++++++++++++++++++++++++++++---
> hw/i386/pc_piix.c | 2 ++
> hw/i386/pc_q35.c | 2 ++
> include/exec/memory.h | 2 ++
> include/hw/loader.h | 1 +
> 6 files changed, 60 insertions(+), 3 deletions(-)
>
> --
> MST