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Re: [Qemu-devel] [PATCH 0/2] pflash (UEFI varstore) migration shortcut f
From: |
Alexey Kardashevskiy |
Subject: |
Re: [Qemu-devel] [PATCH 0/2] pflash (UEFI varstore) migration shortcut for libvirt |
Date: |
Fri, 19 Sep 2014 16:48:28 +1000 |
User-agent: |
Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.1 |
On 08/25/2014 08:33 PM, Paolo Bonzini wrote:
> Il 23/08/2014 12:19, Laszlo Ersek ha scritto:
>> Libvirt is growing support for x86_64 OVMF guests:
>>
>> http://www.redhat.com/archives/libvir-list/2014-August/msg01045.html
>>
>> An important feature of such guests is the persistent store for
>> non-volatile UEFI variables. This is implemented with if=pflash drives.
>> The referenced libvirt patchset sets up the varstore files for
>> single-host use.
>>
>> Wrt. migration, two choices have been considered:
>> (a) full-blown live storage migration for the drives backing pflash
>> devices,
>> (b) vs. a shortcut that exploits the special nature of pflash drives
>> (namely, their minuscule size, and a RAMBlock that keeps the full
>> contents of each pflash drive visible to the guest, and is
>> up-to-date, at all times.)
>>
>> Patch 1/2 is a trivial cleanup (some DPRINTF() calls in pflash_cfi01
>> have bit-rotted). Patch 2/2 seeks to implement choice (b), which is what
>> the libvirt patchset relies on for migration.
>>
>> Thanks,
>> Laszlo
>>
>> Laszlo Ersek (2):
>> pflash_cfi01: fixup stale DPRINTF() calls
>> pflash_cfi01: write flash contents to bdrv on incoming migration
>>
>> hw/block/pflash_cfi01.c | 18 ++++++++++++++++--
>> 1 file changed, 16 insertions(+), 2 deletions(-)
>>
>
> Reviewed-by: Paolo Bonzini <address@hidden>
>
> Alexey/David, I think hw/nvram/spapr_nvram.c should do the same. It
> doesn't have a vmstate, but you can probably use
> qemu_add_vm_change_state_handler to the same effect.
I am not sure I understood the proposal correctly.
Right now we use NVRAM on sPAPR as:
-drive id=id3,if=none,file=qemu_nvram.img
-global spapr-nvram.drive=id3
So the NVRAM file is BlockDriverState and HMP's "migrate -b" copies the
content just fine.
What is missing here? Thanks.
--
Alexey
- Re: [Qemu-devel] [PATCH 0/2] pflash (UEFI varstore) migration shortcut for libvirt,
Alexey Kardashevskiy <=