Re: [Xen-devel] [PATCH 00/07] HVM firmware passthrough

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2012-04-10 at 16:28 +0100, Ross Philipson wrote:
> > -----Original Message-----
> > From: Ian Campbell
> > Sent: Tuesday, April 10, 2012 10:22 AM
> > To: Ross Philipson
> > Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> > Subject: Re: [Xen-devel] [PATCH 00/07] HVM firmware passthrough
> > 
> > On Thu, 2012-04-05 at 21:06 +0100, Ross Philipson wrote:
> > > > I see. So you need to be able to find the individual tables so that
> > > > smbios_type_<N>_init can check for an overriding table <N> in the
> > > > passed-through tables, it seems reasonable to try and avoid needing
> > > > to parse a big lump of tables each time to see if the one you are
> > > > interested in is there.
> > > >
> > > > I think this can work by having .../smbios/<N>/{address,etc} in
> > > > XenStore. You could also have .../smbios/OEM/{...} for the stuff for
> > > > smbios_type_vendor_oem_init, which I think could easily just be a
> > > > single lump?
> > > >
> > > > I think you don't need the same thing for the ACPI side since there
> > > > you just provide secondary tables?
> > >
> > > There could be quite a few SMBIOS tables being passed in. On the order
> > > of 20 - 30 of them and thet are pretty small. It seems a bit odd to
> > > break it up like this for lots of little chunks. There could be more
> > > than one ACPI table also (multiple SSDTs and/or other static tables).
> > > Also the OEM SMBIOS tables are all discrete and they could not go in
> > > as a single lump.
> > 
> > I'm not sure if there are arguments here both for and against having a
> > single smbios blob vs multiple?
> 
> Oh sorry. I am trying to answer 2 different things here. In summary
> what I would like to do is not make any distinction between vendor and
> predefined tables but rather send all SMBIOS tables in as a single
> lump with some sort of internal delimiter structs. If that is
> unacceptable then all the SMBIOS tables would be put in xenstore per
> what you said above (.../smbios/<N>/{address,etc}). It just seems odd
> to me to break up the (usually rather small and potentially numerous)
> SMBIOS tables into individual items passed in xenstore.

What sort of delimiter were you thinking of? Perhaps something as simple
as:
        <length><blob><length><blob>
?

Or can you use the length field in the smbios entry header?

Ian.



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