Re: port-arm/60655: vmt(4) probes the VMware backdoor unconditionally on aarch64 and panics the kernel on hypervisors that do not implement it

[Nick Hudson <nick.hudson%gmx.co.uk@localhost>]

On 05/09/2026 03:30, zakinko%snowrabbit.org@localhost via gnats wrote:
[snip]
> I have sent a patch to qemu-devel making hvf do the same, under the subject
> "target/arm/hvf: implement MDCCSR_EL0 as RAZ"; it has not appeared in the
> archive yet. It is not fixed upstream either: master is 1168 commits past
> v11.1.0 and none of them touch accel/hvf or target/arm/hvf, and 11.1.1 has
> none.
> 

Definitely a qemu bug and I see Mohamed Mediouni agrees.

https://lists.gnu.org/archive/html/qemu-devel/2026-09/msg01794.html


> 
> That said, I do not think this is only QEMU's problem, and I would like your
> opinion on the NetBSD side.

The patch is not correct.

We can do better by not probing when

arm64# acpidump -dt | grep HypervisorId
        HypervisorId=0x00000000554d4551
arm64#