mirror of https://github.com/acidanthera/audk.git
91ff5bba02
In current implementation, core and package level sync uses same semaphores.
Sharing the semaphore may cause wrong execution order.
For example:
1. Feature A has CPU_FEATURE_CORE_BEFORE dependency with Feature B.
2. Feature C has CPU_FEATURE_PACKAGE_AFTER dependency with Feature B.
The expected feature initialization order is A B C:
A ---- (Core Depends) ----> B ---- (Package Depends) ----> C
For a CPU has 1 package, 2 cores and 4 threads. The feature initialization
order may like below:
Thread#1 Thread#2 Thread#3 Thread#4
[A.Init] [A.Init] [A.Init]
Release(S1, S2) Release(S1, S2) Release(S3, S4)
Wait(S1) * 2 Wait(S2) * 2 <------------------------------- Core sync
[B.Init] [B.Init]
Release (S1,S2,S3,S4)
Wait (S1) * 4 <----------------------------------------------------- Package sync
Wait(S4 * 2) <- Core sync
[B.Init]
In above case, for thread#4, when it syncs in core level, Wait(S4) * 2 isn't
blocked and [B.Init] runs. But [A.Init] hasn't run in thread#3. It's wrong!
Thread#4 should execute [B.Init] after thread#3 executes [A.Init] because B
core level depends on A.
The reason of the wrong execution order is that S4 is released in thread#1
by calling Release (S1, S2, S3, S4) and in thread #4 by calling
Release (S3, S4).
To fix this issue, core level sync and package level sync should use separate
semaphores.
In above example, the S4 released in Release (S1, S2, S3, S4) should not be the
same semaphore as that in Release (S3, S4).
Related BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=1311
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
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|---|---|---|
| .. | ||
| CpuFeaturesInitialize.c | ||
| DxeRegisterCpuFeaturesLib.c | ||
| DxeRegisterCpuFeaturesLib.inf | ||
| PeiRegisterCpuFeaturesLib.c | ||
| PeiRegisterCpuFeaturesLib.inf | ||
| RegisterCpuFeatures.h | ||
| RegisterCpuFeaturesLib.c | ||
| RegisterCpuFeaturesLib.uni | ||