The patch adds detailed comments to explain that passing fixed timer period
to mTimerNotifyFunction() is not a bug.
Signed-off-by: Ray Ni <ray...@intel.com>
Cc: Michael D Kinney <michael.d.kin...@intel.com>
Cc: Nate DeSimone <nathaniel.l.desim...@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Rahul Kumar <rahul1.ku...@intel.com>
---
UefiCpuPkg/LocalApicTimerDxe/LocalApicTimerDxe.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/UefiCpuPkg/LocalApicTimerDxe/LocalApicTimerDxe.c
b/UefiCpuPkg/LocalApicTimerDxe/LocalApicTimerDxe.c
index 14ab8fd03d..51c5d39b29 100644
--- a/UefiCpuPkg/LocalApicTimerDxe/LocalApicTimerDxe.c
+++ b/UefiCpuPkg/LocalApicTimerDxe/LocalApicTimerDxe.c
@@ -66,7 +66,17 @@ TimerInterruptHandler (
if (mTimerNotifyFunction != NULL) {
//
- // @bug : This does not handle missed timer interrupts
+ // When mTimerPeriod is 10ms but 1st call of mTimerNotifyFunction() takes
1 hour, the timer
+ // interrupt will be queued and TimerInterruptHandler() will be called
immediately after the
+ // interrupt is re-enabled with gBS->RestoreTPL(). The most precise
implementation should pass
+ // 1 hour as the time period to 2nd call of mTimerNotifyFunction().
+ // Always passing 10ms to mTimerNotifyFunction() might cause some timer
event callbacks to be
+ // invoked later than expected.
+ //
+ // But in reality, DxeCore implements the mTimerNotifyFunction() as a
simple function which
+ // runs at TPL_HIGH_LEVEL. Considering almost all UEFI services require to
run at TPL lower
+ // than TPL_HIGH_LEVEL, the mTimerNotifyFunction() does not have much
heavy work to do. It
+ // should not take longer.
//
mTimerNotifyFunction (mTimerPeriod);
}
@@ -361,9 +371,6 @@ TimerDriverGenerateSoftInterrupt (
OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
if (mTimerNotifyFunction != NULL) {
- //
- // @bug : This does not handle missed timer interrupts
- //
mTimerNotifyFunction (mTimerPeriod);
}
--
2.39.1.windows.1
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#113805): https://edk2.groups.io/g/devel/message/113805
Mute This Topic: https://groups.io/mt/103734966/21656
Group Owner: devel+ow...@edk2.groups.io
Unsubscribe:
https://edk2.groups.io/g/devel/leave/9847357/21656/1706620634/xyzzy
[arch...@mail-archive.com]
-=-=-=-=-=-=-=-=-=-=-=-
