FS#42684 - [kmod] 18-1: Request to add xz support

Attached to Project: Arch Linux
Opened by Pär Forsling (electropura) - Wednesday, 05 November 2014, 00:18 GMT
Last edited by Dave Reisner (falconindy) - Sunday, 16 November 2014, 15:09 GMT
Task Type Feature Request
Category Packages: Core
Status Closed
Assigned To Dave Reisner (falconindy)
Architecture All
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

Description:
In the upcoming kernel release (3.18) there is now a new option to compress the kernel modules with xz in the install phase. This feature requires kmod to be rebuilt with xz support. xz is already in [core] so there should be no downside to letting kmod depend on it.
This task depends upon

Closed by  Dave Reisner (falconindy)
Sunday, 16 November 2014, 15:09 GMT
Reason for closing:  Implemented
Additional comments about closing:  kmod 19
Comment by Dave Reisner (falconindy) - Wednesday, 05 November 2014, 15:37 GMT
I'm curious why you want this -- I'd actually *remove* gzip support if I could (and so would upstream). Everything about compressing kernel modules sucks -- you must now read the entire file *and* decompress it in memory before you can read the ELF headers (as opposed to mmap'ing a single page), and finit_module is a non-option. The only potential gain is reduced disk space (and the reduction over gzip is minimal).
Comment by Pär Forsling (electropura) - Thursday, 06 November 2014, 01:05 GMT
Well, my reasoning was that Arch kernel package already use compressed modules as it is, and the reduction of used diskspace by doing so is rather significant. I did some tests on kernel 3.18-rc3 with Arch standard config and the modules used ~169M of diskspace uncompressed. With gzip -9, which we use now, the disk usage went down to 54M. With xz -6 disk usage was further reduced to 45M. I think I understand why you don't want compression to be used, but as it is Arch *do* use compression, so why not use the better compression algorithm if there is an option?

Loading...