RE: [EXTERNAL] Hyper-V support for IGVM optional parameter

Hyper-V uses device tree extensively as part of our IGVM support for certain configurations.  What I don't know offhand is how much of the DT specification we implement or even support.  I'll see if I can get some information together to help provide some guidance on what would maximize the compatibility between COCONUT-SVSM use of DT and the Hyper-V use of DT.

-Jon

-----Original Message-----
From: Luigi Leonardi <[email protected]>
Sent: Wednesday, May 27, 2026 9:15 AM
To: Jon Lange <[email protected]>
Cc: [email protected]
Subject: [EXTERNAL] Hyper-V support for IGVM optional parameter

[You don't often get email from [email protected]. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]

Hi Jon,

I'm currently working on adding the device tree support for SVSM, and
I was thinking of
adding the DT directive, marking it as optional [1], for every hypervisor.

Do you know if Hyper-V supports this? QEMU currently does not, but I'm
working on it.[2]

This would simplify the logic in igvmbuilder, and when the other
hypervisors support
this directive, it would be totally transparent and require no change to SVSM.

Luigi

[1] https://docs.rs/igvm_defs/0.4.0/igvm_defs/struct.IgvmVariableHeaderType.html
[2]https://lore.kernel.org/qemu-devel/[email protected]/