Laszlo, Thanks for the comments.
(1) Sure. My fault. I thought it’s just very small change for compiler warning. (2) From language point view, it’s a valid warning. But from code logic, it’s invalid. (3) Agree. It’ll be dropped. (4) Agree. I’ll change it. Regards, Jian From: Laszlo Ersek [mailto:ler...@redhat.com] Sent: Tuesday, September 11, 2018 10:56 PM To: Wang, Jian J <jian.j.w...@intel.com>; edk2-devel@lists.01.org Cc: Wu, Hao A <hao.a...@intel.com>; Bi, Dandan <dandan...@intel.com>; Dong, Eric <eric.d...@intel.com> Subject: Re: [edk2] [PATCH] UefiCpuPkg/CpuMpPei: suppress compiler complaining Jian, On 09/11/18 06:47, Jian J Wang wrote: > BZ#: https://bugzilla.tianocore.org/show_bug.cgi?id=1166 > > Cc: Dandan Bi <dandan...@intel.com<mailto:dandan...@intel.com>> > Cc: Hao A Wu <hao.a...@intel.com<mailto:hao.a...@intel.com>> > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Jian J Wang > <jian.j.w...@intel.com<mailto:jian.j.w...@intel.com>> > --- > UefiCpuPkg/CpuMpPei/CpuPaging.c | 23 ++++++++++++++++------- > 1 file changed, 16 insertions(+), 7 deletions(-) (1) Please remember to CC the package maintainers / reviewers on patches. "Maintainers.txt" lists Eric (M) and myself (R) for UefiCpuPkg. It's OK to CC other people as well, of course. (2) Bug 1166 mentions "warning C4701: potentially uninitialized local variable 'StackBase' used". If that warning is invalid (= the variable can never be read unassigned), then we have some suggested language for that; please see <https://bugzilla.tianocore.org/show_bug.cgi?id=607>. Furthermore: > > diff --git a/UefiCpuPkg/CpuMpPei/CpuPaging.c b/UefiCpuPkg/CpuMpPei/CpuPaging.c > index bcb942a8e5..a63421a1af 100644 > --- a/UefiCpuPkg/CpuMpPei/CpuPaging.c > +++ b/UefiCpuPkg/CpuMpPei/CpuPaging.c > @@ -517,7 +517,7 @@ GetStackBase ( > IN OUT VOID *Buffer > ) > { > - EFI_PHYSICAL_ADDRESS StackBase; > + volatile EFI_PHYSICAL_ADDRESS StackBase; (3) "volatile" seems unrelated; I suggest dropping it. (Especially without the comment mentioned in TianoCore#607, "volatile" is totally unjustified and confusing.) > > StackBase = (EFI_PHYSICAL_ADDRESS)(UINTN)&StackBase; > StackBase += BASE_4KB; > @@ -554,6 +554,8 @@ SetupStackGuardPage ( > MpInitLibGetNumberOfProcessors(&NumberOfProcessors, NULL); > MpInitLibWhoAmI (&Bsp); > for (Index = 0; Index < NumberOfProcessors; ++Index) { > + StackBase = 0; > + > if (Index == Bsp) { > Hob.Raw = GetHobList (); > while ((Hob.Raw = GetNextHob (EFI_HOB_TYPE_MEMORY_ALLOCATION, > Hob.Raw)) != NULL) { > @@ -570,12 +572,19 @@ SetupStackGuardPage ( > // > MpInitLibStartupThisAP(GetStackBase, Index, NULL, 0, (VOID > *)&StackBase, NULL); > } > - // > - // Set Guard page at stack base address. > - // > - ConvertMemoryPageAttributes(StackBase, EFI_PAGE_SIZE, 0); > - DEBUG ((DEBUG_INFO, "Stack Guard set at %lx [cpu%lu]!\n", > - (UINT64)StackBase, (UINT64)Index)); > + > + if (StackBase == 0) { > + DEBUG ((DEBUG_ERROR, "Stack base address was not found for > [cpu%lu]!\n", > + (UINT64)Index)); > + ASSERT(StackBase != 0); (4) On the other hand, if it *can* happen in practice that the stack base is not found (and in that case, we should halt), then: * the subject line is wrong, because the compiler warning is *valid*, and we don't suppress it, but fix the issue caught by the compiler; * we must not proceed in a RELEASE build either, therefore an ASSERT is insufficient. A CpuDeadLoop() is necessary. (Again, this only applies if StackBase may be zero here by design.) Thanks Laszlo > + } else { > + // > + // Set Guard page at stack base address. > + // > + ConvertMemoryPageAttributes(StackBase, EFI_PAGE_SIZE, 0); > + DEBUG ((DEBUG_INFO, "Stack Guard set at %lx [cpu%lu]!\n", > + (UINT64)StackBase, (UINT64)Index)); > + } > } > > // > _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
