Re: [edk2-devel] managing memory attributes in PEI

["Michael D Kinney" <michael.d.kinney@intel.com>]

> -----Original Message-----
> From: Ard Biesheuvel <ardb@kernel.org>
> Sent: Tuesday, May 23, 2023 7:59 AM
> To: Kinney, Michael D <michael.d.kinney@intel.com>
> Cc: devel@edk2.groups.io; lersek@redhat.com; Ni, Ray <ray.ni@intel.com>;
> Yao, Jiewen <jiewen.yao@intel.com>; Gerd Hoffmann
> <kraxel@redhat.com>; Taylor Beebe <t@taylorbeebe.com>; Oliver Smith-
> Denny <osd@smith-denny.com>
> Subject: Re: [edk2-devel] managing memory attributes in PEI
> 
> On Tue, 23 May 2023 at 16:49, Kinney, Michael D
> <michael.d.kinney@intel.com> wrote:
> >
> > Ard,
> >
> > I would prefer to keep the IA32 PEI support for OVMF.
> >
> 
> Sure. But does that imply that all enhancements regarding memory
> protections should be introduced there as well?

I would prefer to not support these protections in IA32 PEI.  Same
for IA32 DXE.  Can the proposed PPI do nothing for IA32?

> 
> If so, could you help figure out whether or not running IA32 PEI in
> 32-bit compatible long mode with 4 level page tables would be
> feasible? That would greatly reduce the complexity, given that PEI and
> DXE will be able to share page tables, and will only need one version
> of the page table logic.
> 
> > Ray had proposed an idea to introduce a library class to help
> > with the DXEIPL complexity.  Perhaps that can be combines with
> > this effort.
> >
> 
> Indeed. But the problem remains that creating a set of page tables
> that are incompatible with the present execution mode is highly
> specific to IA32 PEI + X64 DXE, and this impacts the code for all
> other architectures.