On Tue, 3 Mar 2020 at 15:01, Ard Biesheuvel <ard.biesheu...@linaro.org> wrote: > > This series is part of my effort to define a generic EFI boot protocol for > Linux, i.e,. one that is the same across all different architectures that > are able to boot Linux from EFI, and naturally reused the firmware's > infrastructure for authenticated boot and measured boot. > > Path #1 ... #4 implement the 'initrd' dynamic shell command, which takes a > file and exposes it via the LoadFile2 protocol installed on a vendor media > device path with guid LINUX_EFI_INITRD_MEDIA_GUID. This is a Linux specific, > but arch-agnostic way for the OS loader to load an initial ramdisk, while > leaving the firmware (or bootloader) in charge of where the file contents > are served from. This supersedes the currently existing solutions on Linux, > which are either limited to loading from the same volume that the OS loader > was loaded from, or load the initrd into memory first, and use architecture > specific data structures to pass on the information regarding base and size. > > Patch #5 is an update to the integration of the PE/COFF emulator protocol, > to align it more closely with how LoadImage() and StartImage() behave today: > LoadImage() is not restricted to images that can execute natively on the > platform, but also permits loading of cross-type supported images. This means > that any judgement on whether an image can be *started* needs to be deferred > until StartImage(), which is why the invocation of the RegisterImage() > callback needs to be deferred as well. > > Patch #6 implements the PE/COFF emulator protocol so it can start X64 images > that have been loaded on IA32 firmware. This is needed for Linux's so-called > 'mixed mode', which is an elaborate scheme of on-the-fly translation of data > structures and thunking into 32-bit compat mode, allowing X64 Linux kernels > to be used on X64 capable hardware that shipped with IA32 firmware. This > needs support from the loader, and is currently implemented in GRUB (and > OVMF's command line kernel loader) using the EFI handover protocol, which > relies far too much on knowledge of kernel internal data structures, and > circumvents LoadImage and StartImage entirely. > (Note: mixed mode support is mainly targeted at cheap Atom tablets that > shipped with a [cheaper] 32-bit version of Windows, and so this particular > patch is unlikely to help that use case, but it is useful for validation.) > > Patch #7 is new in v4, and modified the initrd Shell command so it aborts > immediately if the Linux initrd media GUID device path already has the > LoadFile2 protocol installed in the protocol database. > > With these changes in place, we can boot x86 mixed-mode Linux straight from > the UEFI Shell > > Shell>initrd fs0:\initrd.img > Shell>fs0:\bzImage root=/dev/vda2 > > Another benefit of this approach is that we can exit cleanly from the loader > (and back to the shell) using the Exit() boot service if any errors occur, > whereas the EFI handover protocol enters a deadloop upon any error that > occurs during execution of the EFI stub. > > Changes since v3: > - pick up some acks > - update patch #6 to sanity check the contents of the .compat section so > we don't overrun the end of the section looking for a compatible entrypoint > - add patch #7 > > Changes since v2: > - incorporate Laszlo's feedback, and add R-b's - I have incorporated all the > feedback given, except for the structure of the shell command > implementation: > it is not my preferred style, but it is correct, and idiomatic for the shell > commands I could find in the tree. > > Changes from v1: > - Use a dynamic UEFI shell command, which is the recommended way of > implementing > new shell commands that are not covered by the UEFI shell specification. It > also makes the command more easily usable on existing platforms, since the > driver can be loaded as an ordinary driver. > - split initrd patch into 4, as requested by Laszlo > - add patch to tweak the LoadImage/StartImage behavior wrt the PE/COFF > emulator > protocol > - return EFI_UNSUPPORTED from PeCoffEmu::RegisterImage() if the image does not > have the required .compat section > > [0] https://edk2.groups.io/g/devel/topic/rfc_patch_1_1_ovmfpkg_add/71177416 > [1] https://edk2.groups.io/g/devel/topic/patch_1_1_ovmfpkg_ia32_add/71272266 > > v2: https://edk2.groups.io/g/devel/topic/patch_v2_0_6_ovmfpkg/71530294 > v3: https://edk2.groups.io/g/devel/message/54932 > > Cc: ler...@redhat.com > Cc: l...@nuviainc.com > Cc: Liming Gao <liming....@intel.com> > > Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2564 > > Ard Biesheuvel (7): > OvmfPkg: add definition of LINUX_EFI_INITRD_MEDIA_GUID > OvmfPkg: add 'initrd' shell command to expose Linux initrd via device > path > ArmVirtPkg: add the 'initrd' dynamic shell command > OvmfPkg: add the 'initrd' dynamic shell command > MdeModulePkg/DxeCore: defer PE/COFF emulator registration to > StartImage > OvmfPkg IA32: add support for loading X64 images > OvmfPkg/LinuxInitrdDynamicShellCommand: bail if initrd already exists >
Merged as 0980779a9ddc..ecb30848fdc9 (after incorporating Laszlo's final review comments) Thanks all! -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#55376): https://edk2.groups.io/g/devel/message/55376 Mute This Topic: https://groups.io/mt/71700580/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
