On 2026-03-23 12:17, Andrew Cooper wrote:
>
> This doesn't really test whether FRED is active. It tests whether the
> OS is not providing strict backwards compatibility, and I think will
> malfunction when there's a hypervisor above Linux providing strict
> backwards compatibility.
>
But that applies equally to IRET, no? If the hypervisor clobbers the segment
selector like IRET would in the interest of compatibility then you have the
same issue.
If the guest is running a FRED kernel and the hypervisor goes in and mucks
with the state after ERETU behind the kernel's back I think you have a much,
much bigger problem.
-hpa
