Re: [PATCH v5 0/6] linux: implement LoadFile2 initrd loading

[Daniel Kiper]

On Tue, Oct 18, 2022 at 09:05:01PM +0200, Ard Biesheuvel wrote:
> This implements the LoadFile2 initrd loading protocol, which is
> essentially a callback interface into the bootloader to load the initrd
> data into a caller provided buffer. This means the bootloader no longer
> has to contain any policy regarding where to load the initrd (which
> differs between architectures and kernel versions) and no longer has to
> manipulate arch specific data structures such as DT or struct bootparams
> to inform the OS where the initrd resides in memory. This is especially
> relevant for the upcoming LoongArch support, which does not use either
> DT or struct bootparams, and would have to rely on the initrd= command
> line interface, which is deprecated and of limited utility [0].
>
> Sample output from booting a recent Linux/arm64 kernel:
>
>   grub> insmod part_msdos
>   grub> linux (hd0,msdos1)/Image
>   grub> initrd (hd0,msdos1)/initrd.img
>   grub> boot
>   EFI stub: Booting Linux Kernel...
>   EFI stub: EFI_RNG_PROTOCOL unavailable
>   EFI stub: Generating empty DTB
>   EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path
>   EFI stub: Exiting boot services...
>   [    0.000000] Booting Linux on physical CPU 0x0000000000 [0x411fd070]
>
> Changes since v4:
> - incorporate review feedback from Daniel regarding whitespace and other
>   minor style deviations
>
> Changes since v3:
> - drop a couple of patches that have been merged independently in the
>   meantime
> - update patch #1 to read the PE image header offset from the file
>   instead of using the harcoded offset
> - add acks from Heinrich and Ilias
>
> Changes since v2:
> - incorporate some ancient feedback from Daniel that I never saw until
>   today. (this is why I am sending two versions of the same series on
>   the same day - apologies for the spam)
>
> [0] The initrd= command line loader can only access files that reside on
> the same volume as the loaded image, which means GRUB would have to
> present this volume abstraction in order to serve the initrd file.
>
> Cc: Daniel Kiper <daniel.kiper@oracle.com>
> Cc: Leif Lindholm <quic_llindhol@quicinc.com>
> Cc: Nikita Ermakov <arei@altlinux.org>
> Cc: Atish Patra <atishp@atishpatra.org>
> Cc: Huacai Chen <chenhuacai@loongson.cn>
> Cc: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
> Cc: dann frazier <dann.frazier@canonical.com>
> Cc: Julian Andres Klode <julian.klode@canonical.com>
> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
>
> Ard Biesheuvel (6):
>   efi: move MS-DOS stub out of generic PE header definition
>   linux/arm: unify ARM/arm64 vs Xen PE/COFF header handling
>   linux/arm: account for COFF headers appearing at unexpected offsets
>   efi/efinet: Don't close connections at fini_hw() time
>   efi: implement LoadFile2 initrd loading protocol for Linux
>   linux: ignore FDT unless we need to modify it

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> for all patches...

Though one comment. Probably I would pull stdbool.h into include/grub/types.h
in the patch #5. If I do not hear any objections I will do that for you before
merging the patches.

Thank you for doing this work guys! And sorry it took so long to review
all these patches...

Daniel