Re: [Qemu-devel] [qemu RFC] qapi: add "firmware.json"

[Thomas Huth <thuth@redhat.com>]

On 10.04.2018 11:16, Laszlo Ersek wrote:
> On 04/10/18 08:27, Gerd Hoffmann wrote:
>>   Hi,
>>
>>> - I considered adding wildcards (say, blacklist "all" i440fx machtypes,
>>> present and future, for SMM-requiring OVMF builds), but then you get
>>> into version sorting and similar mess. I considered fnmatch() --
>>> basically simple ? and * wildcards -- but that's not expressive enough.
>>
>> I'd suggest whitelist with wildcards.  So the smm builds would get
>> "pc-q35-*".
>>
>> libvirt knows about aliases, so it should be able to handle the "q35"
>> shortcut like "pc-q35-${latest}".
>>
>> Or do you see another issue?
> 
> Well, one issue I see is version sorting; I should say "Q35 but no
> earlier than 2.4", and lexicographically, "2.11" sorts before "2.4".
> 
> Anyway (also asking for Thomas's input here): if we run with your idea
> to refer to exact mapping methods / firmware *implementation* types that
> we know libvirt implements / supports as a "white box", do we still deem
> machine type identification necessary? Because, libvirt already knows
> (for example) that "ovmf_smm" requires pc-q35-2.4 or later. So we just
> have to make a *reference* to that knowledge in the JSON file.

I think you really need a way to specify the machine there. Latest
example from QEMU 2.12: We've now got two uboot binaries in the tree,
pc-bios/u-boot.e500 and pc-bios/u-boot-sam460-20100605.bin. Both are
uboot, both are for ppc, but u-boot.e500 only works with the "ppce500"
machine and the other one only works with the "sam460ex" machine. How
would you teach libvirt such a relationship without an explicit machine
type identification field there?

 Thomas