can't boot fallback

slackhack · 2007-03-10 16:47:09

here's what i have in grub:

# (0) Arch Linux
title  Arch Linux
root   (hd0,1)
kernel /boot/vmlinuz26 root=/dev/hda2 ro vga=773
initrd /boot/kernel26.img

# (1) Arch Fallback
title  Arch Fallback
root   (hd0,1)
kernel /boot/vmlinuz26 root=/dev/hda2 ro vga=773 rootfstype=ext3
initrd /boot/kernel26-fallback.img

the first one boots, the second one doesn't. kernel panic, cannot open root device (0,0). also tried without the rootfstype. what's the problem? shouldn't the fallback image have everything in it to boot almost anything?

>>edit: tried adding rootdelay=20 in case something wasn't getting loaded. it delayed, but still didn't boot.

>>edit2: okay, i fixed it by adding ide_disk to modules in /etc/mkinitcpio.conf, and running mkinitcpio to make test.img, which i added to grub in place of kernel26-fallback.img.

now what do i do when adding a new cpu/motherboard? just boot the test.img? i guess i'm confused, because it seems like the test.img i just made is for my current hardware, and i thought that the fallback img was a "failsafe" for most hardware. but it seems that kernel26-fallback.img doesn't even work for my current hardware. so how do i add the new hardware (which will be totally different with via chipset vs. nvidia, etc.) and still be able to boot? :confused:

Last edited by slackhack (2007-03-10 18:15:37)

slackhack · 2007-03-13 13:33:23

can anyone help with this? i'm running out of time to test the hardware to see if i have to return it in case it's defective. i need to know specifically how to boot a new motherboard if the fallback.img doesn't work. do i just boot to live cd or install disk and chroot / then rebuild image? is there a way to make a failsafe fallback image before installing the new hardware that will contain almost all common modules known to man? etc. thanks

slackhack · 2007-03-16 15:21:19

got everything working. no fallback image would work, i don't really know what's wrong with the fallback image process, but it doesn't seem to include the necessary drivers for some reason. i had to build a kernel myself while still on the old hardware, install the new hardware, then boot the kernel i made to get to a command prompt. once i did that, i just made a new image with mkinitcpio, and after loading a couple of modules manually, everything works.

one question i have is, in the wiki, it lists this as the command for regenerating the fallback image:

mkinitcpio -c /boot/mkinitcpio-kernel26.conf -g /boot/kernel26.img

maybe there's something i don't understand about all this initramfs stuff -- and maybe that's why i couldn't get the fallback to work -- but shouldn't that command list /boot/kernel26-fallback.img instead of /boot/kernel26.img? i mean won't that command just overwrite your default image? i really don't get it, maybe someone can explain it to me like you're talking to a 3 year old. because it seems to me the default fallback image should have worked and it didn't, and it seems like that command won't create a fallback but will overwrite your regular image. thanks

Last edited by slackhack (2007-03-16 15:21:52)

phrakture · 2007-03-16 16:37:44

It generates whatever you name it. If you want a special image, you can run "mkinitcpio -c /etc/super-image.conf -g /boot/optimius-prime.lol" - the naming doesn't matter.

If you want to regenerate things for a given kernel, they typically install "preset" sets of images. For kernel26, you can run "mkinitcpio -p kernel26" to regenerate both the normal and fallback images.

slackhack · 2007-03-16 21:23:13

phrakture wrote:

It generates whatever you name it. If you want a special image, you can run "mkinitcpio -c /etc/super-image.conf -g /boot/optimius-prime.lol" - the naming doesn't matter.
If you want to regenerate things for a given kernel, they typically install "preset" sets of images. For kernel26, you can run "mkinitcpio -p kernel26" to regenerate both the normal and fallback images.

thanks phrakture. i understand that you can name it whatever you want, but what i'm questioning is if someone followed the wiki exactly as it's written, they would actually overwrite their kernel26.img and not have a fallback image at all, is that correct? i guess it wouldn't matter if mkinitcpio-kernel26.conf is the same config file they used to generate the image in the first place (except they wouldn't have a fallback). but what if they usually let pacman make the image with the default /etc/mkinitcpio.conf file? then wouldn't they be overwriting their default kernel26 with a kernel26 generated from the mkinitcpio-kernel26.conf? if so, it seems the wiki should be changed to prevent n00bs (like me ) from overwriting something that could screw up their ability to boot, is all i'm wondering.

regarding the command you mentioned, are you saying that running -p kernel26 generates 2 images: kernel26.img and kernel26-fallback.img? sorry for the dumb questions, i thought i understood the initramfs system, but when the kernel26-fallback.img didn't work for me i started questioning if i do in fact understand what's going on. thanks.

phrakture · 2007-03-16 22:51:51

slackhack wrote:

if so, it seems the wiki should be changed to prevent n00bs (like me ) from overwriting something that could screw up their ability to boot, is all i'm wondering.

That's the precise reason it's a wiki. If there's something confusing, and you know why it's confusing, feel free to edit the page and fix it 8)

slackhack · 2007-03-17 03:15:52

phrakture wrote:

slackhack wrote:
if so, it seems the wiki should be changed to prevent n00bs (like me ) from overwriting something that could screw up their ability to boot, is all i'm wondering.
That's the precise reason it's a wiki. If there's something confusing, and you know why it's confusing, feel free to edit the page and fix it 8)

exactly. i just wasn't 100 percent sure by any means, and i didn't want to change something that was right to something wrong based on my own misunderstanding. just thought i'd clarify it for myself first, thanks.

Arch Linux

#1 2007-03-10 16:47:09

can't boot fallback

#2 2007-03-13 13:33:23

Re: can't boot fallback

#3 2007-03-16 15:21:19

Re: can't boot fallback

#4 2007-03-16 16:37:44

Re: can't boot fallback

#5 2007-03-16 21:23:13

Re: can't boot fallback

#6 2007-03-16 22:51:51

Re: can't boot fallback

#7 2007-03-17 03:15:52

Re: can't boot fallback

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