On Wed, Mar 16, 2011 at 22:42, Thomas Bächler <thomas@xxxxxxxxxxxxx> wrote: > Am 16.03.2011 17:12, schrieb KESHAV P.R.: >> On Wed, Mar 16, 2011 at 20:12, KESHAV P.R. <skodabenz@xxxxxxxxx> wrote: >>> On Wed, Mar 16, 2011 at 20:09, Gaetan Bisson <bisson@xxxxxxxxxxxxx> wrote: >>>> [2011-03-16 19:58:23 +0530] KESHAV P.R.: >>>>> Now that kernel 2.6.38 supports xz (lzma2, not lzma), how >>>>> about using it as the default compression for the kernel and >>>>> initramfs. mkinitcpio simply requires COMPRESSION="xz" to generate >>>>> lzma2 compressed initramfs. But xz compressed kernel requires change >>>>> in the config option and once module-init-toools supports xz >>>>> compressed modules we can say good bye to gzip. >>>> >> >> mkinitcpio.conf requires COMPRESSION="xz --check=crc32" , not simply >> "xz" since crc64 (default) checksum is not supported by kernel >> de-compressor. See >> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=Documentation/xz.txt;hb=HEAD > > Thanks for this info. There is one request to remove the "-9" default > compression ratio, so this is probably a good time to change how > compression is handled for mkinitcpio. The advantage of xz over lzma > shouldn't be that big in any case. > > Kernel documentation recommends using a 1MiB dictionary max (for the kernel, maybe more for initramfs), not 64MiB that is required for -9 option. Otherwise it is better to have specific compression level option for each format in mkinitcpio.conf instead of the actual mkinitcpio script. In case of xz, kernel docs recommends I am typing this from Arch x86_64 2.6.38 with xz --check=crc32 -9 compressed initramfs. I don't know about any problems with -9 option, except maaybe amount of memory required to decompress. - Keshav Offnote: What happened to Big Kernel Lock (in the config)
