Does it depend on vPMU _for Linux guests_ or in general? My impression
is that LBR can be used by the guest independent of the PMU.
I think only for Linux guests.
I googled how to enable LBR on other guests(except Linux guests),
e.g. Windows, and got no developer manuals about it.
Here is an article about it:
http://www.codeproject.com/Articles/517466/Last-branch-records-
and-branch-tracing
it says:
"bit 8 of DR7 represents bit 0 of DebugCtl. This is the LBR bit."
Don't worry about the operating system in the guest: you are just
emulating a processor feature, you do not care about anything except
what is written in the Intel SDM.
You can use kvm-unit-tests
(https://git.kernel.org/cgit/virt/kvm/kvm-unit-tests.git/) to write a
test for your feature. There are existing tests for debugging features.
ok.
Regards,
Jian
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