Should dracut uncompress compressed kernel modules before installing into the initramfs?

[Nowa-Ammerlaan]

A kernel that is configured to compress modules (for example CONFIG_MODULE_COMPRESS_XZ=y) still supports loading uncompressed modules. Given that it is size-wise more efficient to compress a bunch of uncompressed files, compared to compressing a bunch of files that are individually already compressed. It might make sense for Dracut to decompress modules it finds before including them in the initramfs.

The same holds for firmware files (CONFIG_FW_LOADER_COMPRESS_XZ=y).

To put this in numbers, an UKI for the same kernel with the same user space utilities, but with pre-xz-compressed kernel modules and firmware is 356.352 kb larger on my system.

[Artoria2e5]

Yes, yes, yes. This should absolutely be an option: I did some testing in March 2024 and it helps a strong initramfs compressor (e.g. zstd -15) compress quite a bit further. Compressed firmware is a candidate too. https://github.com/AOSC-Dev/aosc-os-abbs/discussions/6006#discussioncomment-9443065

patch https://github.com/dracut-ng/dracut-ng/pull/1176

[stale[bot]]

This issue is being marked as stale because it has not had any recent activity. It will be closed if no further activity occurs. If this is still an issue in the latest release of Dracut and you would like to keep it open please comment on this issue within the next 7 days. Thank you for your contributions.

[Artoria2e5]

Stale bot considered harmful, chapter 1048577

well it got me up to clean up a PR. maybe it helps

[stale[bot]]

This issue is being marked as stale because it has not had any recent activity. It will be closed if no further activity occurs. If this is still an issue in the latest release of Dracut and you would like to keep it open please comment on this issue within the next 7 days. Thank you for your contributions.