Re: [PATCH v2 0/16] Support for custom EFI firmware

[Christian Ludwig <christian_ludwig@genua.de>]

Hi,

thanks for taking the time to review the patchset.

On Mon, 2026-10-05 at 16:36 +0200, Fiona Ebner wrote:
> Format Extensions
> =================
> 
> Would it be an issue to require/restrict file extensions here, i.e.
> only
> allow names ending with '.fd', '.raw' and '.img' or similar?

There is no issue with that. The OVMF build yields firmware files with
a '.fd' extension by default.

> 1. It would protect against potential confusion, e.g. otherwise,
> there
> can be a filename ending in '.qcow2'. While the code will look at the
> returned format which is hard-coded/enforced to be 'raw', such a name
> would still be confusing.

Agreed. I suggest we restrict it to '.fd' only. That extension is not
in use, yet. So there is no confusion.

> 2. It would also allow us to extend support to non-raw formats in the
> future. For example, we probably want to support IGVM [0] files as
> well
> at some point. Have you already looked at that this format and what
> do
> you think about it regarding your use case?

We have not looked into IGVM in detail, yet. But it looks promising.
And it may well live next to OVMF files in efi-firmware storage. Both
formats fit the current design. Both file types are immutable and
shared across multiple VMs.

> [0]: https://www.qemu.org/docs/master/system/igvm.html
> 
> 'bios' as property string
> =========================
> 
> I wonder if we should turn 'bios' into a property string with the
> firmware file as a sub-property? This would couple the properties
> more
> tightly.

Sure. I'll give it a shot. The tight coupling of these properties has
led us to move the custom efi firmware option to the VM.Config.Options
permission in this patchset revision. We felt that moving the bios
option to VM.Config.HWType is a big breaking change and off the table.
 
> ===
> 
> Happy to hear opinions about these from you and also other
> developers!
> 
> Best Regards,
> Fiona

I'll consider your comments from patch reviews. No complaints there.
Will rework and send an update.


 - Christian