Re: [Patch] UefiCpuPkg/MpInitLib: Keep compatible with former solution.

[Laszlo Ersek <lersek@redhat.com>]

On 10/26/17 07:59, Eric Dong wrote:
> For some special platforms (such as Ovmf), it is possible
> that, some APs start up *and finish* before the remaining
> APs not start up *at all*. In this case, the enhance

(1) I think the word "not" should be removed from the above line, so
that we get: "some APs start up *and finish* before the remaining APs []
start up *at all*".

(2) For the subject line: can we add "AP counting" or "AP collection"
somehow? For example:

UefiCpuPkg/MpInitLib: Keep compatible with former AP counting solution.


I don't insist, but I think these changes would improve the commit
message. They can be implemented before pushing. Either way,

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Thank you for the quick update, Eric and Jeff!
Laszlo

> solution by changes 0594ec41 not works as expected.
> 
> This change remove check CpuMpData->CpuCount logic to let old
> solution still workable if platform owner still set a long
> time for PcdCpuApInitTimeOutInMicroSeconds. It's platform
> owner's response to decide which solution to use.
> 
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Jeff Fan <vanjeff_919@hotmail.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Eric Dong <eric.dong@intel.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/MpLib.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> index 48f930b..18060fd 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> @@ -936,15 +936,20 @@ WakeUpAP (
>      }
>      if (CpuMpData->InitFlag == ApInitConfig) {
>        //
> -      // Wait for one potential AP waken up in one specified period
> +      // Here support two methods to collect AP count through adjust
> +      // PcdCpuApInitTimeOutInMicroSeconds values.
>        //
> -      if (CpuMpData->CpuCount == 0) {
> -        TimedWaitForApFinish (
> -          CpuMpData,
> -          PcdGet32 (PcdCpuMaxLogicalProcessorNumber) - 1,
> -          PcdGet32 (PcdCpuApInitTimeOutInMicroSeconds)
> -          );
> -      }
> +      // one way is set a value to just let the first AP to start the
> +      // initialization, then through the later while loop to wait all Aps
> +      // finsh the initialization.
> +      // The other way is set a value to let all APs finished the initialzation.
> +      // In this case, the later while loop is useless.
> +      //
> +      TimedWaitForApFinish (
> +        CpuMpData,
> +        PcdGet32 (PcdCpuMaxLogicalProcessorNumber) - 1,
> +        PcdGet32 (PcdCpuApInitTimeOutInMicroSeconds)
> +        );
>  
>        while (CpuMpData->MpCpuExchangeInfo->NumApsExecuting != 0) {
>          CpuPause();
>