Re: [PATCH 0/3] alpha: self-extracting compressed kernel images

[Magnus Lindholm]

Hi Matt,

On Sat, Sep 12, 2026 at 9:55 PM Matt Turner <mattst88@xxxxxxxxx> wrote:
>
> Alpha is the last architecture whose boot loader decompresses the kernel
> itself: aboot carries its own inflate code, so vmlinux.gz has always
> been plain gzip, and adding a compression format meant writing a
> decompressor for aboot as well as for the kernel.
>
> Build a self-extracting image instead, a small ELF stub with the
> compressed vmlinux linked in, which aboot loads and enters like any
> other kernel. The compression format then becomes an ordinary kernel
> Kconfig choice, and all seven formats become available: xz gives the
> smallest image, 5547496 bytes against 7677280 for the equivalent gzip
> one. The build now emits arch/alpha/boot/vmlinuz, since the image is no
> longer gzip data.
>
> The SRM netboot path (bootpz.c) has its own boot protocol and keeps
> using gzip.
>
> Signed-off-by: Matt Turner <mattst88@xxxxxxxxx>


Nice series! I've done some testing during the weekend and it all looks
good to me, thanks for doing this.

Regards

Magnus


> ---
> Matt Turner (3):
>       xz: add arch-specific tuning for alpha
>       alpha: add self-extracting compressed kernel boot stub
>       alpha: support the remaining kernel compression formats
>
>  arch/alpha/Kconfig                       |   7 ++
>  arch/alpha/Makefile                      |   6 +-
>  arch/alpha/boot/.gitignore               |   2 +
>  arch/alpha/boot/Makefile                 |  16 ++-
>  arch/alpha/boot/compressed/.gitignore    |   3 +
>  arch/alpha/boot/compressed/Makefile      |  63 ++++++++++
>  arch/alpha/boot/compressed/head.S        |  36 ++++++
>  arch/alpha/boot/compressed/misc.c        | 209 +++++++++++++++++++++++++++++++
>  arch/alpha/boot/compressed/trampoline.S  |  46 +++++++
>  arch/alpha/boot/compressed/vmlinux.lds.S |  83 ++++++++++++
>  arch/alpha/boot/compressed/vmlinux.scr   |  10 ++
>  scripts/xz_wrap.sh                       |   5 +
>  12 files changed, 478 insertions(+), 8 deletions(-)
> ---
> base-commit: 4407825b2f96b0e48a4bd08ab196b50a30eb3aef
> change-id: 20260912-alpha-kernel-compression-2043f806fb75
>
> Best regards,
> --
> Matt Turner <mattst88@xxxxxxxxx>
>