Re: [libvirt] [Qemu-devel] Configuring pflash devices for OVMF firmware
On Mon, 28 Jan 2019 at 12:40, Gerd Hoffmann <kraxel(a)redhat.com> wrote:
The tricky part is the access control here. On physical hardware
you
typically have one flash rom, say 16M below 4G (on x86).
Our pflash device doesn't allow to define multiple regions, so we use
multiple pflash devices instead, each with different access permissions
(code vs. vars). Because of that they are more dynamic than they are on
phyiscal hardware, x86 sizes them according to the size of the firmware
images (arm is easier here, we have fixed size and location no matter
how big the firmware images are).
So I think the options we have are:
(a) leave pflash as-is, which pretty much implies physaddr and size
must be user-configurable.
(b) add support for multiple regions to pflash, so one can attach
multiple blockdev at different offsets to a single pflash device.
The latter makes more sense to me -- we should model what the
hardware actually has, because the guest can tell the difference.
(Migration compat is left as an exercise for the reader :-))
thanks
-- PMM