[solved]4.14: no xxhash, zstd_compress, zstd_decompress; in initramfs?

probackup-nl · 2017-12-08 18:12:26

Since kernel 4.14 the mkinitcpio generated initramfs files do include these 3 new modules:

1. xxhash
2. zstd_compress
3. zstd_decompress

These modules are related to the new (Facebook) Zstandard compression algo.

Initramfs here uses lz4.

Can these 3 modules be removed/excluded from the mkinitcpio mechanism?
Or does boot fail without them?

In case zstd is removable from initramfs, how to remove the zstd modules (permanently)?

Last edited by probackup-nl (2017-12-24 09:49:12)

jasonwryan · 2017-12-08 18:24:13

http://blog.falconindy.com/articles/opt … tcpio.html

loqs · 2017-12-08 18:56:05

Perhaps you could investigate what is pulling the modules in.

$ bsdcpio -it < /boot/initramfs-linux.img | grep zstd
63704 blocks

probackup-nl · 2017-12-08 19:18:19

@Ioqs Btrfs file system is pulling in these modules: see compress_zstd at https://btrfs.wiki.kernel.org/index.php … M_FEATURES

# bsdcpio -it < /boot/initramfs-linux-tiny.img | grep zstd
usr/lib/modules/4.14.4-1-ARCH/kernel/zstd_decompress.ko
usr/lib/modules/4.14.4-1-ARCH/kernel/zstd_compress.ko

loqs · 2017-12-08 19:26:18

So the same answer as to your previous btrfs question https://bbs.archlinux.org/viewtopic.php?id=231884 if you need btrfs then you need those modules.
You also seem to have a habit of not marking any of your topics as solved.

probackup-nl · 2017-12-09 10:48:59

I don't need the Zstandard neither RAID modules, because I don't use disk compression neither RAID. The raid6_pq module does slow down my boot and this kernel release 4.14 zstd module does increase initramfs size after lz4 compression by 12% (+0.6 MiB on 5.2 MiB before).

$ modinfo /usr/lib/modules/4.14.4-1-ARCH/kernel/fs/btrfs/btrfs.ko.gz | grep depends
depends:        zstd_compress,zstd_decompress,raid6_pq,xor

Where to reach the developers that are able to minify btrfs module loading (and soften the btrfs dependencies) on Arch Linux?

Last edited by probackup-nl (2017-12-09 10:51:53)

Slithery · 2017-12-09 11:02:02

Patches welcome.

If you come up with a good solution and post it on the relevant mailing list, you might get the devs attention.

probackup-nl · 2017-12-09 11:05:44

My best guess is now:

https://btrfs.wiki.kernel.org/index.php/Project_ideas

Arch Linux

#1 2017-12-08 18:12:26

[solved]4.14: no xxhash, zstd_compress, zstd_decompress; in initramfs?

#2 2017-12-08 18:24:13

Re: [solved]4.14: no xxhash, zstd_compress, zstd_decompress; in initramfs?

#3 2017-12-08 18:56:05

Re: [solved]4.14: no xxhash, zstd_compress, zstd_decompress; in initramfs?

#4 2017-12-08 19:18:19

Re: [solved]4.14: no xxhash, zstd_compress, zstd_decompress; in initramfs?

#5 2017-12-08 19:26:18

Re: [solved]4.14: no xxhash, zstd_compress, zstd_decompress; in initramfs?

#6 2017-12-09 10:48:59

Re: [solved]4.14: no xxhash, zstd_compress, zstd_decompress; in initramfs?

#7 2017-12-09 11:02:02

Re: [solved]4.14: no xxhash, zstd_compress, zstd_decompress; in initramfs?

#8 2017-12-09 11:05:44

Re: [solved]4.14: no xxhash, zstd_compress, zstd_decompress; in initramfs?

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