You have a good point with the proposed order for enabling the PCD. I will make that update in a V4 later today.
Thanks, Michael > -----Original Message----- > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Laszlo > Ersek > Sent: Monday, October 14, 2019 11:50 AM > To: devel@edk2.groups.io; Kubacki, Michael A > <michael.a.kuba...@intel.com> > Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>; Gao, Liming > <liming....@intel.com>; Justen, Jordan L <jordan.l.jus...@intel.com>; Wu, > Hao A <hao.a...@intel.com> > Subject: Re: [edk2-devel] [PATCH V3 9/9] OvmfPkg: Disable variable runtime > cache > > On 10/14/19 20:08, Kubacki, Michael A wrote: > > Sets gEfiMdeModulePkgTokenSpaceGuid.PcdEnableVariableRuntimeCache > > to FALSE in OvmfPkgIa32.dsc, OvmfPkgIa32X64.dsc, and OvmfPkgX64.dsc > so > > that when SMM_REQUIRE is TRUE, the SMM variable driver will not use > > the runtime variable cache. > > > > This is done for OvmfPkg because it currently depends upon a SMM > > variable GetVariable ()implementation as a simple method to exercise > > the SMM driver stack. This allows the following commands to be used > > for variables such as Boot####, BootOrder, and BootNext to test SMM > > timing and stability differences on the BSP (e.g. CPU#0) vs an AP > > (e.g. CPU#1). > > # taskset -c 0 efibootmgr > > # taskset -c 1 efibootmgr > > > > Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> > > Cc: Laszlo Ersek <ler...@redhat.com> > > Cc: Liming Gao <liming....@intel.com> > > Cc: Jordan Justen <jordan.l.jus...@intel.com> > > Cc: Hao A Wu <hao.a...@intel.com> > > Signed-off-by: Michael Kubacki <michael.a.kuba...@intel.com> > > --- > > OvmfPkg/OvmfPkgIa32.dsc | 1 + > > OvmfPkg/OvmfPkgIa32X64.dsc | 1 + > > OvmfPkg/OvmfPkgX64.dsc | 1 + > > 3 files changed, 3 insertions(+) > > > > diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc index > > 66e944436a..4861e2342b 100644 > > --- a/OvmfPkg/OvmfPkgIa32.dsc > > +++ b/OvmfPkg/OvmfPkgIa32.dsc > > @@ -428,6 +428,7 @@ > > !if $(SMM_REQUIRE) == TRUE > > gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|TRUE > > gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmEnableBspElection|FALSE > > + > gEfiMdeModulePkgTokenSpaceGuid.PcdEnableVariableRuntimeCache|FALS > E > > !endif > > > > [PcdsFixedAtBuild] > > diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc > b/OvmfPkg/OvmfPkgIa32X64.dsc > > index 51c2bfb44f..f316d97d6a 100644 > > --- a/OvmfPkg/OvmfPkgIa32X64.dsc > > +++ b/OvmfPkg/OvmfPkgIa32X64.dsc > > @@ -433,6 +433,7 @@ > > !if $(SMM_REQUIRE) == TRUE > > gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|TRUE > > gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmEnableBspElection|FALSE > > + > gEfiMdeModulePkgTokenSpaceGuid.PcdEnableVariableRuntimeCache|FALS > E > > !endif > > > > [PcdsFixedAtBuild] > > diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc index > > ba7a758844..546649f0a2 100644 > > --- a/OvmfPkg/OvmfPkgX64.dsc > > +++ b/OvmfPkg/OvmfPkgX64.dsc > > @@ -433,6 +433,7 @@ > > !if $(SMM_REQUIRE) == TRUE > > gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|TRUE > > gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmEnableBspElection|FALSE > > + > gEfiMdeModulePkgTokenSpaceGuid.PcdEnableVariableRuntimeCache|FALS > E > > !endif > > > > [PcdsFixedAtBuild] > > > > For this patch: > > Reviewed-by: Laszlo Ersek <ler...@redhat.com> > > And many thanks for accommodating this use case! > > However, I'd prefer the following order of changes: > > - patch 7: introduce the PCD with default FALSE value > - patch 9: set the PCD explicitly to FALSE in OvmfPkg > - patch 10 (new patch): flip the PCD default value to TRUE > > Because with v3, if someone were to bisect an issue, using OVMF, and the > bisection landed them at patch 7 or at patch 8, they'd see a > (transitory) change in variable caching behavior. > > Thanks, > Laszlo > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#48936): https://edk2.groups.io/g/devel/message/48936 Mute This Topic: https://groups.io/mt/34536814/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
