Agree, thanks comments. > -----Original Message----- > From: Ni, Ray <ray...@intel.com> > Sent: Thursday, May 11, 2023 3:48 PM > To: Wu, Jiaxin <jiaxin...@intel.com>; devel@edk2.groups.io; > kra...@redhat.com > Cc: Dong, Eric <eric.d...@intel.com>; Zeng, Star <star.z...@intel.com>; > Kumar, Rahul R <rahul.r.ku...@intel.com> > Subject: RE: [edk2-devel] [PATCH v1 1/3] UefiCpuPkg/SecCore: Migrate page > table to permanent memory > > Jiaxin, > Let's keep using 48 or 57. > We can use separate patch to clean all existing code to use 47 and 56. > > Thanks, > Ray > > > -----Original Message----- > > From: Wu, Jiaxin <jiaxin...@intel.com> > > Sent: Thursday, May 11, 2023 1:08 PM > > To: devel@edk2.groups.io; kra...@redhat.com; Ni, Ray <ray...@intel.com> > > Cc: Dong, Eric <eric.d...@intel.com>; Zeng, Star <star.z...@intel.com>; > > Kumar, Rahul R <rahul.r.ku...@intel.com> > > Subject: RE: [edk2-devel] [PATCH v1 1/3] UefiCpuPkg/SecCore: Migrate page > > table to permanent memory > > > > What's your comments to the existing code logic for the PhysicalAddressBits > in > > the CreateIdentityMappingPageTables()? Looks all doesn't consider the sign- > > extended case? is it reasonable create the paging but not used? All system > with > > long mode are sign-extended? > > > > // > > // IA-32e paging translates 48-bit linear addresses to 52-bit physical > addresses > > // when 5-Level Paging is disabled, > > // due to either unsupported by HW, or disabled by PCD. > > // > > ASSERT (PhysicalAddressBits <= 52); > > if (!Page5LevelSupport && (PhysicalAddressBits > 48)) { > > PhysicalAddressBits = 48; > > } > > > > > > > -----Original Message----- > > > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Gerd > > > Hoffmann > > > Sent: Wednesday, May 10, 2023 3:48 PM > > > To: devel@edk2.groups.io; Ni, Ray <ray...@intel.com> > > > Cc: Wu, Jiaxin <jiaxin...@intel.com>; Dong, Eric <eric.d...@intel.com>; > > Zeng, > > > Star <star.z...@intel.com>; Kumar, Rahul R <rahul.r.ku...@intel.com> > > > Subject: Re: [edk2-devel] [PATCH v1 1/3] UefiCpuPkg/SecCore: Migrate > page > > > table to permanent memory > > > > > > On Wed, May 10, 2023 at 02:48:52AM +0000, Ni, Ray wrote: > > > > Gerd, > > > > My understanding is that when code dereferences memory address, the > code > > > itself is responsible for > > > > supplying the sign-extended linear address. > > > > The page table creation logic still maps the entire linear memory space > > > supported by the CPU. > > > > > > > > Why do you think covering the half of the space is better? > > > > > > edk2 boot services operate on the assumption that everything is identity > > > mapped, only runtime services know the concept of virtual addresses. > > > > > > The lower half of the address space can be identity-mapped (virtual > > > address == physical address). The upper half can not, so I think it's > > > better for efi boot services to restrict themself to the lower half. > > > > > > take care, > > > Gerd > > > > > > > > > > > > > > >
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