On 5/2/2024 1:52 PM, Chang S. Bae wrote:
This brief mention may prompt questions about why the hardware must
refuse to run the test under these conditions. Because this is part of
its internal, we'd go back to folks who wrote this test and will grab
their write-up to provide the logic behind this requirement.
Okay, I got the write-up sooner than expected:
In-Field Scan (IFS) is a destructive test meaning that it will overwrite
the existing state to achieve the goal of testing the logic. IFS must
ensure that it is able to return the CPU back to the OS in the same
architectural state as it was prior to IFS start. To do this
architectural state (register state visible to the OS) is saved in a
cache [*]. The cache has a limited size. When AMX is in use, the state
of the AMX logic that needs to be saved is too large to be accommodated
in the cache. Therefore OS must clear the AMX logic from being in use
prior to IFS start.
[*] This cache is software-inaccessible space.
Thanks,
Chang
