Boot different kernel with yaboot?

[ubuntubrian]

I have all of these kernel images in /boot and I wanted to try booting some of the older ones to see if they correct the issues I still have with Hardy on my TiBook G4,powerpc.
Is there a simple way? Do I need to edit yaboot.conf (I'm sure I do)and if so what do I put in there?
Would something like this work? (The first 2 images are what are in the conf file already and I didn't include the mac boot files.

image=/boot/vmlinux
	label=Linux
	read-only
	initrd=/boot/initrd.img
	append="quiet splash"

	root = /dev/hda8
image=/boot/vmlinux.old
	label=old
	read-only
	initrd=/boot/initrd.img.old
	append="quiet splash"
	root = /dev/hda8
image=/boot/vmlinux-2.6.15-52-powerpc
	label=testkernel
	read-only
	initrd=/boot/initrd.img.old
	append="quiet splash"
	root = /dev/hda8

Thanks for any help!

[tiresia]

Do not change your yaboot.conf! You do not need.
Just hit TAB when yaboot starts, and you can choose the kernel you want to boot.

[ubuntubrian]

Thanks for the reply. I only have "Linux" and "old", which I have always had. I'd like to boot one of the other kernels in /boot. Here're the contents of /boot:

/boot$ ls
abi-2.6.12-9-powerpc initrd.img-2.6.15-51-powerpc
abi-2.6.15-20-powerpc initrd.img-2.6.15-52-powerpc
abi-2.6.15-21-powerpc initrd.img-2.6.24-19-powerpc
abi-2.6.15-22-powerpc initrd.img-2.6.24-19-powerpc.bak
abi-2.6.15-23-powerpc initrd.img-2.6.24-19-powerpc-smp
abi-2.6.15-26-powerpc initrd.img-2.6.24-19-powerpc-smp.bak
abi-2.6.15-27-powerpc initrd.img.old
abi-2.6.15-28-powerpc System.map-2.6.12-8-powerpc
abi-2.6.15-29-powerpc System.map-2.6.12-9-powerpc
abi-2.6.15-51-powerpc System.map-2.6.15-20-powerpc
abi-2.6.15-52-powerpc System.map-2.6.15-21-powerpc
abi-2.6.24-19-powerpc System.map-2.6.15-22-powerpc
abi-2.6.24-19-powerpc-smp System.map-2.6.15-23-powerpc
config-2.6.12-8-powerpc System.map-2.6.15-26-powerpc
config-2.6.12-9-powerpc System.map-2.6.15-27-powerpc
config-2.6.15-20-powerpc System.map-2.6.15-28-powerpc
config-2.6.15-21-powerpc System.map-2.6.15-29-powerpc
config-2.6.15-22-powerpc System.map-2.6.15-51-powerpc
config-2.6.15-23-powerpc System.map-2.6.15-52-powerpc
config-2.6.15-26-powerpc System.map-2.6.24-19-powerpc
config-2.6.15-27-powerpc System.map-2.6.24-19-powerpc-smp
config-2.6.15-28-powerpc vmlinux
config-2.6.15-29-powerpc vmlinux-2.6.12-8-powerpc
config-2.6.15-51-powerpc vmlinux-2.6.12-9-powerpc
config-2.6.15-52-powerpc vmlinux-2.6.15-20-powerpc
config-2.6.24-19-powerpc vmlinux-2.6.15-21-powerpc
config-2.6.24-19-powerpc-smp vmlinux-2.6.15-22-powerpc
initrd.img vmlinux-2.6.15-23-powerpc
initrd.img-2.6.12-8-powerpc vmlinux-2.6.15-26-powerpc
initrd.img-2.6.12-9-powerpc vmlinux-2.6.15-27-powerpc
initrd.img-2.6.15-20-powerpc vmlinux-2.6.15-28-powerpc
initrd.img-2.6.15-21-powerpc vmlinux-2.6.15-29-powerpc
initrd.img-2.6.15-22-powerpc vmlinux-2.6.15-51-powerpc
initrd.img-2.6.15-23-powerpc vmlinux-2.6.15-52-powerpc
initrd.img-2.6.15-26-powerpc vmlinux-2.6.24-19-powerpc
initrd.img-2.6.15-27-powerpc vmlinux-2.6.24-19-powerpc-smp
initrd.img-2.6.15-28-powerpc vmlinux.old
initrd.img-2.6.15-29-powerpc


Any help?

[tiresia]

Sorry, but I had not understood your question. If you compiled a new kernel and you want to try it, yes you should change your yaboot.conf in order to boot a different kernel. Once you are done, don't forget to run

ybin -v

[ubuntubrian]

Thanks for the quick reply Tiresia! I'm glad I cleared that up for you but....
These are old kernels that have been in /boot since Dapper and I've never removed them. there are a couple of things that I'm trying to accomplish.
the first is to see if I can boot one of the older kernels and if so the question is how do I modify my yaboot.conf file? I have read much on it but am still unsure which is why I included my hypothetical configuration in the first post which references a kernel image in /boot.
I have not compiled a new kernel but may try that as I have Mac-On-Linux installed which will not run with my current kernel 2.6.24-19, but people report will with a Gutsy kernel. Compiling that is a whole other matter that I have never even tried but I'm game.
So, to sum up, are these images in /bott actually bootable and if so just how do I edit my yaboot.conf file to use them?
BTW, I was following this which has good info but for a newbie there's too much ambiguity:http://www.linuxchix.org/content/cou...acking/lesson4

Many, many thanks!

[tiresia]

First of all, make a backup of your yaboot.conf

sudo cp /etc/yaboot.conf /etc/yaboot.conf-backup

You need to specify in yaboot.conf following:

1. The filesystem path to the kernel image (image=)
2. The related ramdisk image for the kernel you want to load (initrd=)

Since it seems that you want to boot the kernel 'vmlinux-2.6.15-52-powerpc', make a symlink to that kernel with the name 'vmlinux.oldest' (or whatever you want) and a symlink to its ramdisk image with 'initrd.img.oldest' (or whatever you want):

sudo ln -s /boot/vmlinux-2.6.15-52-powerpc /boot/vmlinux.oldest

sudo ln -s /boot/initrd.img-2.6.15-52-powerpc /boot/initrd.img.oldest

Your yaboot.conf should look like this:

image=/boot/vmlinux
	label=Linux
	read-only
	initrd=/boot/initrd.img
	append="quiet splash"
	root = /dev/hda8

image=/boot/vmlinux.old
	label=old
	read-only
	initrd=/boot/initrd.img.old
	append="quiet splash"
	root = /dev/hda8

image=/boot/vmlinux.oldest
	label=oldest
	read-only
	initrd=/boot/initrd.img.oldest
	append="quiet splash"
	root = /dev/hda8

Save the file and run ybin

sudo ybin -v

Restart your computer, at the boot: prompt, hit TAB. Now you should see the three kernels, that you can choose: Linux, old and oldest. Type 'oldest' (or the label you hace choosen to select the vmlinux-2.6.15-52-powerpc kernel).

---

P.S. I'm not sure, that your system will work, but you can try anyway…
I guess you know these links:
http://mac-on-linux.sourceforge.net/....php/Main_Page
http://mac-on-linux.sourceforge.net/...n_Instructions
https://help.ubuntu.com/community/MacOnLinuxHowto

[ubuntubrian]

Thanks so much for the clear instructions! this was on some of the wikis, etc. but the actual editing was unclear to me and you cleared it right up tiresia. I realize that the older kernels may not run with Hardy but I can also now install a Gutsy kernel and try that and yes, I am going for MOL as well as trying to get better performance as Hardy is much slower than Dapper was on my TiBook.
Interestingly, it is now suspending and waking fine and if I leave it booted and don't shut down the performance improves over time. Odd...

[ubuntubrian]

BTW, do you run MOL on Hardy tiresia?

[tiresia]

BTW, do you run MOL on Hardy tiresia?

No, unfortunatly I can't, because MOL doesn't run on powerpc64…
I can only use Qemu to emulate an OS, but it does not work with emulate a powerpc architecture (even if it says it does)

[ubuntubrian]

hi Sayad. Is part of your post missing? I don't understand it otherwise.
I have MOL installed and it ran great on Dapper but it will not on Hardy. Actually it's OS X drivers that can't be installed so i guess that OS 9 would run but I don't have that installed.
I have read that various kernel patches and building a kernel allow it to run on Hardy but the simplest is a post that stated that it would run of a Gutsy kernel. I'm not sure how that works yet and if I could just install the drivers once booted into a Gutsy kernel and run MOL or not.
Getting a Gutsy kernel to boot would be a first step.