Firmware chooses to use 5-level paging when the platform using this firmware claims to boot 5-level paging OS only.
Usually, firmware uses 4-level paging to keep maximum OS compability. Thanks, Ray > -----Original Message----- > From: Gerd Hoffmann <kra...@redhat.com> > Sent: Wednesday, May 10, 2023 5:18 PM > To: devel@edk2.groups.io; pedro.falc...@gmail.com > Cc: Andrew Fish <af...@apple.com>; Kinney, Michael D > <michael.d.kin...@intel.com>; Ni, Ray <ray...@intel.com>; Ard Biesheuvel > <a...@kernel.org> > Subject: Re: [edk2-devel] Side effects of enabling PML5 in EFI > > On Tue, May 09, 2023 at 06:24:03PM +0100, Pedro Falcato wrote: > > Hi all, > > > > (+CC people vaguely related to the EFI spec, the PML5 implementation > > and kernel EFI boot code) > > > > As a result of the latest 5-level paging patches, I've been looking > > into how tiano supports PML5. > > This raised a question: Doesn't enabling PML5 in-firmware break > > compatibility with non-PML5-aware bootloaders and kernels? > > kernels yes, bootloaders probably not (unless the bootloader not the > kernel calls exitbootservices). > > > So, how is any of this supposed to work? > > edk2 is relatively late to the party, so with everybody else supporting > 5-level paging already it might not be much of an issue in practice even > though there is no compatibility handling (I know of) in edk2. > > When running your operating system museum in virtual machines you have > the option to just turn off 5-level paging support in the virtual cpu. > > take care, > Gerd -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#104535): https://edk2.groups.io/g/devel/message/104535 Mute This Topic: https://groups.io/mt/98788948/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/leave/9847357/21656/1706620634/xyzzy [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
