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

[Michael S. Tsirkin]

On Wed, Nov 19, 2014 at 02:59:12PM +0000, Dr. David Alan Gilbert wrote:
> * Paolo Bonzini (address@hidden) wrote:
> > 
> > 
> > On 19/11/2014 15:26, Dr. David Alan Gilbert wrote:
> > > * Paolo Bonzini (address@hidden) 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

I feel it's an implementation detail that really shouldn't
be pushed out to users.


> > 
> > 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 / address@hidden / Manchester, UK
> > > 
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK