Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Paolo Bonzini (pbonzini@redhat.com) wrote:
> 
> 
> On 19/11/2014 15:26, Dr. David Alan Gilbert wrote:
> > * Paolo Bonzini (pbonzini@redhat.com) wrote:
> >>
> >>
> >> On 19/11/2014 15:13, Dr. David Alan Gilbert wrote:
> >>> Since we've wondered off the actual ACPI table stuff into general
> >>> ROM sizing, I'd like to propose some concrete fixes:
> >>>
> >>>   1) We explicitly name the bios file in a .romfile attribute for
> >>>      all ROMs.
> >>>   2) The code that uses .romfile has an expansion for $MACHINETYPE
> >>>   3) We actually symlink all of those together, anyone who wants/has
> >>>      to deal with different versions can downstream.
> >>>   4) The machine types contain size attributes for the ROMs that
> >>>      are generoously larger than the ROMs anyone currently uses.
> >>>
> >>> I think 1..3 should deal with those of us who have to deal with different
> >>> ROM versions on different machine types.
> >>
> >> It should, but it's a solution in search of a problem.
> > 
> > Well we already do something close to 1 & 2 downstream but more ad-hoc;
> > it's just a generalisation (and 4 from padding the size of our images).
> > So we already had that problem.
> 
> Upstream too.  See pxe-* vs. efi-* NIC option ROMs.  The latter includes
> both PXE firmware for BIOS and EFI drivers.  We keep two copies because
> they have different sizes.  Having explicit expansions for $MACHINETYPE
> would be hugely overkill, in my opinion.

Yes it is, but it's simple and feels easy to understand.

Dave

> 
> Paolo
> 
> >>
> >>> 4 might be good enough for the ACPI tables if you can bound it.
> >>
> >> Already doing that (rounding to 128k, warning if >64k), but it is not a
> >> definitive solution.
> >>
> >> We also do (4) for ROMs, since VGA BIOSes use only 36k out of 64k and
> >> iPXE ROMs use only ~200k out of 256k.
> >>
> >> Paolo
> > --
> > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> > 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK