[Qemu-devel] Re: [PATCH 0/3]: Add UUID command-line option

[Gleb Natapov]

On Mon, Jul 28, 2008 at 05:42:12PM +0200, Chris Lalancette wrote:
> Anthony Liguori wrote:
> > 
> > That makes me sad that they merged that.  What a terribly complicated 
> > way to do something that's relatively simple.
> 
> Heh.  OK.  Well, that's where we are today, which may not be the best place, 
> but
> it's where both Gleb and I based the work off of.
> 
> I'll ask a naive question about CMOS; is there room in a standard CMOS to 
> store
> a UUID?  From my limited knowledge about it, I thought the CMOS was a quite
> small region of ROM, and so there wouldn't really be room for something like a
> 128-byte UUID.  I could be totally wrong about that, though.
> 
CMOS has enough memory for UUID, but UUID is not the only thing that
needs to be passed to BIOS, so eventually we can run out of space there.
For example we have a requirement to pass additional ACPI tables that
user may specify on command line. There is no enough space to put those
tables into CMOS. What I did is that: BIOS passes to qemu address where to
store additional tables (via backdoor) and qemu copies them there. To
this scheme to work there should be bidirectional channel between qemu
and BIOS. Other then that I am not particularly attached to vmware
backdoor :)

--
                        Gleb.