Re: [PATCH v4 09/35] OvmfPkg/OvmfXen: use a TimerLib instance that depends only on the CPU


Roger Pau Monné
 

On Mon, Jul 29, 2019 at 04:39:18PM +0100, Anthony PERARD wrote:
The ACPI Timer isn't present in a PVH guest, but local APIC works on
both PVH and HVM.

Note that the use of SecPeiDxeTimerLibCpu might be an issue with a
driver of type DXE_RUNTIME_DRIVER. I've attempted to find out which of
the DXE_RUNTIME_DRIVER uses the TimerLib at runtime. I've done that by
replacing the TimerLib evaluation in
[LibraryClasses.common.DXE_RUNTIME_DRIVER] by a different one and
checking every module that uses it (with the --report-file=report
build option).

ResetSystemRuntimeDxe is calling the TimerLib API at runtime to do the
operation "EfiResetCold", so this may never complete if the OS have
disabled the Local APIC Timer.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689
Signed-off-by: Anthony PERARD <anthony.perard@...>
Acked-by: Laszlo Ersek <lersek@...>
---

Notes:
v4:
- reworded the first sentence, use "not present" instead of "don't work".
Thanks, I'm afraid I cannot comment on the change itself, but the
comment message is accurate now :).

Roger.

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