[Qemu-devel] [PATCH 0/2] pflash (UEFI varstore) migration shortcut for libvirt

[Laszlo Ersek]

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(-)

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1.8.3.1