Hao, Certain OS loaders may fail to boot when 5-level paging is used. PCD can be used to restrict to 4-level paging.
> -----Original Message----- > From: Wu, Hao A > Sent: Tuesday, July 23, 2019 10:06 AM > To: devel@edk2.groups.io; Ni, Ray <ray...@intel.com> > Cc: Dong, Eric <eric.d...@intel.com>; Laszlo Ersek <ler...@redhat.com> > Subject: RE: [edk2-devel] [PATCH 3/4] MdeModulePkg/DxeIpl: Introduce PCD > PcdUse5LevelPageTable > > > -----Original Message----- > > From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of Ni, > > Ray > > Sent: Monday, July 22, 2019 4:16 PM > > To: devel@edk2.groups.io > > Cc: Dong, Eric; Laszlo Ersek > > Subject: [edk2-devel] [PATCH 3/4] MdeModulePkg/DxeIpl: Introduce PCD > > PcdUse5LevelPageTable > > > > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2008 > > > > The PCD indicates if 5-Level Paging will be enabled in long mode. > > 5-Level Paging will not be enabled when the PCD is TRUE but CPU > > doesn't support 5-Level Paging. > > > > Signed-off-by: Ray Ni <ray...@intel.com> > > Cc: Eric Dong <eric.d...@intel.com> > > Cc: Laszlo Ersek <ler...@redhat.com> > > --- > > MdeModulePkg/MdeModulePkg.dec | 7 +++++++ > > > Hello, > > Please help to add the PCD description string definitions in MdeModulePkg.uni. > > One question, is this PCD introduced for the consideration of memory > consumption by the page table entries? Or is there any other purpose? > > Best Regards, > Hao Wu > > > > 1 file changed, 7 insertions(+) > > > > diff --git a/MdeModulePkg/MdeModulePkg.dec > > b/MdeModulePkg/MdeModulePkg.dec > > index 12e0bbf579..21388595a9 100644 > > --- a/MdeModulePkg/MdeModulePkg.dec > > +++ b/MdeModulePkg/MdeModulePkg.dec > > @@ -1991,6 +1991,13 @@ [PcdsFixedAtBuild, PcdsPatchableInModule, > > PcdsDynamic, PcdsDynamicEx] > > # @Prompt The address mask when memory encryption is enabled. > > > > gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrM > > ask|0x0|UINT64|0x30001047 > > > > + ## Indicates if 5-Level Paging will be enabled in long mode. 5-Level > > Paging > > will not be enabled > > + # when the PCD is TRUE but CPU doesn't support 5-Level Paging. > > + # TRUE - 5-Level Paging will be enabled.<BR> > > + # FALSE - 5-Level Paging will not be enabled.<BR> > > + # @Prompt Enable 5-Level Paging support in long mode. > > + > > gEfiMdeModulePkgTokenSpaceGuid.PcdUse5LevelPageTable|FALSE|BOOLE > > AN|0x0001105F > > + > > ## Capsule In Ram is to use memory to deliver the capsules that will be > > processed after system > > # reset.<BR><BR> > > # This PCD indicates if the Capsule In Ram is supported.<BR> > > -- > > 2.21.0.windows.1 > > > > > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#44258): https://edk2.groups.io/g/devel/message/44258 Mute This Topic: https://groups.io/mt/32556534/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
