Hi Laszlo, > -----Original Message----- > From: Laszlo Ersek [mailto:ler...@redhat.com] > Sent: Wednesday, January 15, 2020 6:05 PM > To: Dong, Eric <eric.d...@intel.com>; devel@edk2.groups.io > Cc: Ni, Ray <ray...@intel.com> > Subject: Re: [PATCH] UefiCpuPkg/Library/MpInitLib: Remove BSP index == 0 > Assumption. > > On 01/15/20 07:06, Eric Dong wrote: > > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2392 > > > > Current code implementation assumes BSP index is 0 at the begin. > > This code change removes this assumption. It get BSP index from the > > saved data structure if it existed. > > > > Cc: Ray Ni <ray...@intel.com> > > Cc: Laszlo Ersek <ler...@redhat.com> > > Signed-off-by: Eric Dong <eric.d...@intel.com> > > --- > > UefiCpuPkg/Library/MpInitLib/MpLib.c | 10 ++++++---- > > 1 file changed, 6 insertions(+), 4 deletions(-) > > > > diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c > > b/UefiCpuPkg/Library/MpInitLib/MpLib.c > > index 6ec9b172b8..922c87b766 100644 > > --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c > > +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c > > @@ -636,7 +636,7 @@ ApWakeupFunction ( > > // to initialize AP in InitConfig path. > > // NOTE: IDTR.BASE stored in CpuMpData- > >CpuData[0].VolatileRegisters points to a different IDT shared by all APs. > > // > > - RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, > FALSE); > > + RestoreVolatileRegisters > > + (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, > > + FALSE); > > InitializeApData (CpuMpData, ProcessorNumber, BistData, > ApTopOfStack); > > ApStartupSignalBuffer = > > CpuMpData->CpuData[ProcessorNumber].StartupApSignal; > > > > @@ -1615,6 +1615,7 @@ MpInitLibInitialize ( > > UINTN ApResetVectorSize; > > UINTN BackupBufferAddr; > > UINTN ApIdtBase; > > + UINT64 BspTopOfStack; > > > > OldCpuMpData = GetCpuMpDataFromGuidedHob (); > > if (OldCpuMpData == NULL) { > > @@ -1677,7 +1678,7 @@ MpInitLibInitialize ( > > CpuMpData->BackupBufferSize = ApResetVectorSize; > > CpuMpData->WakeupBuffer = (UINTN) -1; > > CpuMpData->CpuCount = 1; > > - CpuMpData->BspNumber = 0; > > + CpuMpData->BspNumber = OldCpuMpData != NULL ? > OldCpuMpData->BspNumber : 0; > > CpuMpData->WaitEvent = NULL; > > CpuMpData->SwitchBspFlag = FALSE; > > CpuMpData->CpuData = (CPU_AP_DATA *) (CpuMpData + 1); > > @@ -1704,11 +1705,12 @@ MpInitLibInitialize ( > > // Don't pass BSP's TR to APs to avoid AP init failure. > > // > > VolatileRegisters.Tr = 0; > > - CopyMem (&CpuMpData->CpuData[0].VolatileRegisters, > > &VolatileRegisters, sizeof (VolatileRegisters)); > > + CopyMem > > + (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, > > + &VolatileRegisters, sizeof (VolatileRegisters)); > > // > > // Set BSP basic information > > // > > - InitializeApData (CpuMpData, 0, 0, CpuMpData->Buffer + > > ApStackSize); > > + BspTopOfStack = CpuMpData->Buffer + (CpuMpData->BspNumber + 1) > * > > + CpuMpData->CpuApStackSize; InitializeApData (CpuMpData, > > + CpuMpData->BspNumber, 0, BspTopOfStack); > > // > > // Save assembly code information > > // > > > > The patch seems reasonable to me (although I have not tried verifying that > all necessary spots are updated). > > However, there is one thing I certainly don't understand, and the commit > message doesn't explain it. In the "BspTopOfStack" calculation, why do we > change the *second* factor, when we change the multiplication from: > > (0 + 1) * ApStackSize > > (where the (0 + 1) is implied in the old code), to: > > (CpuMpData->BspNumber + 1) * CpuMpData->CpuApStackSize > > ? > > I understand why the *first* factor is changed -- we basically replace "0" > with > "CpuMpData->BspNumber" --; what I don't understand is why we replace > "ApStackSize" with "CpuMpData->CpuApStackSize", in the second factor. > > ... Higher up in the code, we have: > > CpuMpData->CpuApStackSize = ApStackSize; > > so this part of the patch might actually have no effect. But, even then, I > think > it makes the patch harder to understand. So in that case, I'd suggest sticking > with "ApStackSize", just for keeping the patch simpler. > [[Eric]] driver has two places to call InitializeApData (). Here is one and the other in ApWakeupFunction(). InitializeApData (CpuMpData, ProcessorNumber, BistData, ApTopOfStack); At that function, it calculates the ApTopOfStack like below: ApTopOfStack = CpuMpData->Buffer + (ProcessorNumber + 1) * CpuMpData->CpuApStackSize;
I update new code to follow this coding style. I think after this change, the exit two code pieces are follow the same coding style. So I think we can keep my original change. Thanks, Eric > Thanks > Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#53291): https://edk2.groups.io/g/devel/message/53291 Mute This Topic: https://groups.io/mt/69712223/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
