Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios

[Gleb Natapov <gleb@redhat.com>]

On Tue, Oct 12, 2010 at 10:45:58AM -0700, H. Peter Anvin wrote:
> On 10/12/2010 10:41 AM, Gleb Natapov wrote:
> > On Tue, Oct 12, 2010 at 10:35:51AM -0700, H. Peter Anvin wrote:
> >> On real hardware it is shared between BIOS and the OS, actually.
> >>
> > Guest OS can write in qemu CMOS too. But what is it useful for? Most of
> > its content is not standard AFAIK.
> > 
> 
> This is true to some extent -- there is some standard content, and some
> further can be described via ACPI tables.  However, my point was mostly
> that it is an existing model for nonvolatile storage which also works on
> hardware (and is vastly simpler albeit smaller in size than ESCD).
> 
And my point is why would we want nonvolatile storage for BIOS settings
in qemu. It doesn't provide anything that can't be done through command
line and configured nicely by virt-manager and it introduces one more
file to carry around with your VM. And if the idea is to create it on
the fly then it is no longer nonvolatile and is not better then fw_cfg.
If we want nonvolatile storage for some reason I would agree that CMOS
is good candidate for that except of its size. How much can you fit into
128 byte? Less then one tweet.
--
			Gleb.