On Fri, Dec 06, 2024 at 03:25:00PM +0100, Ard Biesheuvel wrote: > From: Ard Biesheuvel <ardb@xxxxxxxxxx> > > For historical reasons, the legacy decompressor code on various > architectures supports 7 different compression types for the compressed > kernel image. > > EFI zboot is not a compression library museum, and so the options can be > limited to what is likely to be useful in practice: > > - GZIP is tried and tested, and is still one of the fastest at > decompression time, although the compression ratio is not very high; > moreover, Fedora is already shipping EFI zboot kernels for arm64 that > use GZIP, and QEMU implements direct support for it when booting a > kernel without firmware loaded; > > - ZSTD has a very high compression ratio (although not the highest), and > is almost as fast as GZIP at decompression time. > > Reducing the number of options makes it less of a hassle for other > consumers of the EFI zboot format (such as QEMU today, and kexec in the > future) to support it transparently without having to carry 7 different > decompression libraries. > > Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx> > Cc: Peter Jones <pjones@xxxxxxxxxx> > Cc: Pingfan Liu <piliu@xxxxxxxxxx> > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> Acked-by: Gerd Hoffmann <kraxel@xxxxxxxxxx> take care, Gerd
