Chen, Volatile is to tell compiler this variable maybe changed by other threads. Compiler must access the value from memory instead of the old value in its registers. This is different with spinlock that is to protect shared memory between multiple threads.
For this case, CpuState may be updated by BSP/AP. I prefer to keep volatile type. Do you meet any issue if keepping this type? Besides it, I also suggest to add volatile for the following variable. CpuData->Parameter CpuData->Procedure Thanks! Jeff -----Original Message----- From: Chen Fan [mailto:chen.fan.f...@cn.fujitsu.com] Sent: Tuesday, March 03, 2015 1:06 PM To: edk2-devel@lists.sourceforge.net Cc: Fan, Jeff; Justen, Jordan L Subject: [v2 4/4] UefiCpuPkg/MpSerivce: remove volatile qualifier because manipulating CpuState always with lock protection. so volatile qualifier is redundant. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Chen Fan <chen.fan.f...@cn.fujitsu.com> --- UefiCpuPkg/CpuDxe/CpuMp.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/UefiCpuPkg/CpuDxe/CpuMp.h b/UefiCpuPkg/CpuDxe/CpuMp.h index cb3460f..e54b571 100644 --- a/UefiCpuPkg/CpuDxe/CpuMp.h +++ b/UefiCpuPkg/CpuDxe/CpuMp.h @@ -92,7 +92,7 @@ typedef struct { EFI_PROCESSOR_INFORMATION Info; SPIN_LOCK CpuDataLock; INTN LockSelf; - volatile CPU_STATE State; + CPU_STATE State; EFI_AP_PROCEDURE Procedure; VOID *Parameter; -- 1.9.3 ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ edk2-devel mailing list edk2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/edk2-devel
