initramfs image compression other than gzip

Question

can the initramfs image be compressed by a method other than gzip, such as lzma?

Maciej Piechotka · Accepted Answer · 2010-09-19 00:31:04Z

up vote 1 down vote accepted

Yes. I use in-kernel initrd and it offers at least the following methods:

EDIT: You can use it on external file and with LZMA (at least on ubuntu).

EDIT 2: Wikipedia states that Linux kernel supports gzip, bzip and lzma (depending, of course, what algorithms are compiled in).

edited Sep 19 '10 at 0:31

answered Sep 18 '10 at 21:50

Maciej Piechotka
6,34711238

	does it must be "in-kernel" initrd (and what do you actually means by in-kernel) ? what if I have external file of initrd? – uray Sep 18 '10 at 22:00
	I would be very surprised if it used different files. As in what it actually means - you can build-in initrd in kernel just as you can build-in modules. I have / on LVM so I need to have initrd script - and the easiest way for me is to build it into kernel. – Maciej Piechotka Sep 18 '10 at 22:04
	sorry but the 'initrd' in this question is actually an initramfs file or a filesystem that initially loaded by kernel, or the file which usually pointed by grub like this `initrd /boot/initramfs-2.6.33.3-85.fc13.i686.img`, maybe I used wrong term (I edited the question)? – uray Sep 18 '10 at 23:04
	As I stated in edit - yes at least in Ubuntu. I'd be very surprised if it hadn't work. You haven't used the wrong term but I said what 1) I have experience with 2) what I found (that Ubuntu do support it) 3) what I expect. Anyway - why not just try it. – Maciej Piechotka Sep 19 '10 at 0:29
	ok I tried it, it confirmed the kernel can load initramfs with lzma compression, I must compile the kernel using `CONFIG_RD_LZMA=y`. but it will KP if the compression parameter is other than default, for example if i try `lzma -e -9 -z` for initramfs image it will leads to KP. – uray Sep 19 '10 at 6:46

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