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 via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR port-arm/60655; it has been noted by GNATS.

From: Nick Hudson <nick.hudson%gmx.co.uk@localhost>
To: gnats-bugs%netbsd.org@localhost,
 port-arm-maintainer%netbsd.org@localhost,
 gnats-admin%netbsd.org@localhost,
 netbsd-bugs%netbsd.org@localhost,
 Showta Ishizaki <zakinko%snowrabbit.org@localhost>
Cc: 
Subject: Re: port-arm/60655: vmt(4) probes the VMware backdoor unconditionally
 on aarch64 and panics the kernel on hypervisors that do not implement it
Date: Sat, 5 Sep 2026 13:49:45 +0100

 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.
 >=20
 
 Definitely a qemu bug and I see Mohamed Mediouni agrees.
 
 https://lists.gnu.org/archive/html/qemu-devel/2026-09/msg01794.html
 
 
 >=20
 > 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=3D0x00000000554d4551
 arm64#