Initramfs doesn't support Luks despite flag with genkernel?

jbiggs12 · n00b Joined: 09 Mar 2012 Posts: 27

Hi all,

I'm attempting to install a Luks-encrypted lvm system on my computer, and I'm having a bit of difficulty with booting. I compile the kernel, specifically selecting the appropriate options in the menuconfig, and then running genkernel with the --luks flag. Despite this, whenever I boot into the kernel the ramdisk complains that it doesn't support Luks, and then gives up the ghost. Shouldn't the initramfs support this if genkernel generates it (which it did)? I looked into creating an initramfs myself and it blew my socks off. I suppose I could learn it if I really put myself to it, but it'd be nice if I could fix this by adding / removing a single option with genkernel / menuconfig.[/b]

cach0rr0 · Posted: Sat Mar 10, 2012 2:36 am Post subject:

never worked properly for me either

ergo, i wrote this guide: http://whitehathouston.com/documentation/gentoo/initramfs_howto.htm
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jbiggs12 · n00b Joined: 09 Mar 2012 Posts: 27

So genkernel just won't do it, period?

cach0rr0 · Posted: Sat Mar 10, 2012 4:27 am Post subject:

for *me* it was epic fail trying to get genkernel to do it, when i first tried way back in the day, and my most recent attempt ~2 years ago
so i finally bashed out a way to make a very simple small one of my own

the doc says it's supported - maybe other people have had better experiences than myself, so i cant write it off completely

jbiggs12 · n00b Joined: 09 Mar 2012 Posts: 27

Seems doable. I take it that if I want LVM support I have to copy all of the lvm-related binaries as well?

cach0rr0 · Posted: Sat Mar 10, 2012 6:25 am Post subject:

jbiggs12 · n00b Joined: 09 Mar 2012 Posts: 27

Tried your guide, the kernel keeps insisting that init isn't there despite me using chmod +x, then trying chmod 777, then trying passing a path to the kernel with init=. I'm going to try compiling it into the kernel to see if I can get any different results.

jbiggs12 · n00b Joined: 09 Mar 2012 Posts: 27

Update: Tried compiling it in with the kernel, but it still doesn't work. I'm also noticing that before it says it couldn't find init, it complains that it was "unable to open an initial console." I double checked and I enabled in-kernel initramfs. Is there some option that I'm missing? (Once I boot onto my livecd I'll post my kernel config)

edit: Kernel config: http://paste.pocoo.org/show/563954/
menu.lst: http://paste.pocoo.org/show/563955/

cach0rr0 · Posted: Sun Mar 11, 2012 4:36 am Post subject:

in your menu.lst there is no 'initrd' line.

what did you namethe initramfs?

Your menu.lst/grub.conf should look very similar to this:

jbiggs12 · n00b Joined: 09 Mar 2012 Posts: 27

I left the initrd blank because I embedded the initramfs into the kernel. Do I still need to put an initrd line? Here's the init script that I used: http://paste.pocoo.org/show/564053/

cach0rr0 · Posted: Sun Mar 11, 2012 5:07 am Post subject:

your init has no line to mount anything at /dev

ergo things like urandom, console, null, sda, arent going to be accessible

I see you unmounting it, but not mounting it. You *do* have devtmpfs support in the kernel, so all your missing is a line like this below your proc/sys mounts:

jbiggs12 · n00b Joined: 09 Mar 2012 Posts: 27

I went with your advice and am now passing an image to the kernel instead, and when I recompiled the kernel I got rid of devtmpfs support and just populated it manually, hence the absence of the line. It's still saying "Failed to execute init -- no init found", despite my best efforts. I'm going to get on the livecd and repost the init script, menu.lst, and the output of ls -liaR.

edit:
ls -liaR /usr/src/initramfs/: http://paste.pocoo.org/show/564235/
/init: http://paste.pocoo.org/show/564233/
menu.lst: http://paste.pocoo.org/show/564234/

edit of the edit:I noticed that lvm isn't in sbin, I'm moving it there now. I doubt that this was the cause of the problem, though, because it's not finding the init.

jbiggs12 · n00b Joined: 09 Mar 2012 Posts: 27

*d'oh* turns out I didn't emerge busybox with USE=static. It boots now, but gives me the error "cannot open device /dev/sda4 for read-only access", which, from some simple googling, appears to be the result of unsupported hardware. I'll dig through my kernel config to see if I've left anything out; here's lspci -n:

jbiggs12 · n00b Joined: 09 Mar 2012 Posts: 27

I got it to work!

I followed the instructions of the in-kernel component of this guide: http://forums.gentoo.org/viewtopic.php?t=79. Working now, although the kernel spits out a bunch of nonsense regarding the usb devices that I can probably just suppress with quiet. Thanks for your help with the initramfs guide, I really wouldn't have made it otherwise.

cach0rr0 · Posted: Mon Mar 12, 2012 1:20 am Post subject:

wicked. good feeling isnt it?

even better if over the course of fighting with it you figured out more or less how things piece together. which should make the next time you have to do this a bit easier (knock on wood)

thing is, all of these automated tools....if they work the first time out of the box, great, that's a major time saver. But when they dont, it can be a PITA trying to dig through them and troubleshoot. For example, if there's something wrong with the 'init' that you need to change, is it easier to spot in a 2,000 line automagic init that tries to account for every single possible different setup any human on the planet might use? Or is it easier to spot in a 20 line init that you made for your own hardware?

When you do things yourself, in somewhat of a minimalist fashion, there are only so many "moving parts", so youre only looking 5 or 6 different spots for where something might be broken.
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