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#1 2007-09-10 00:24:17

kagerato
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Registered: 2007-09-10
Posts: 45
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Custom packages may result in kernel panic on reboot

The kernel will fail to boot after installation with an "init not found" message if certain packages from base are unselected/missing.  I originally thought that all the necessary packages were force-selected for installation (regardless of user choices), but upon closer examination this does not seem the case.  The offending package in my case, as far as I can tell, is "mkinitcpio".  When this package is manually excluded, the installation will not result in a bootable system.

As I understand it, mkinitcpio is used for creating an early userspace environment for the purpose of detecting and loading required kernel modules.  In my case, I'm guessing that 'init' cannot be found because the root filesystem cannot be mounted.  This would make sense if the early userspace is missing and the filesystem module never loads.

Is it a bug that mkinitcpio can be omitted during installation?  Or are there configurations where it would not be required (root filesystem on ext2, maybe) ?

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#2 2007-09-10 02:29:52

F
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Registered: 2006-10-09
Posts: 322

Re: Custom packages may result in kernel panic on reboot

No, this isn't a bug. This is freedom.

At this time, however, I can't think of any justifiable reasons to get rid of mkinitcpio except to, perhaps, play with an alternative (if there is one, or if you're trying to make one, for instance).

Last edited by F (2007-09-10 02:32:37)

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#3 2007-09-10 04:46:32

kagerato
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Registered: 2007-09-10
Posts: 45
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Re: Custom packages may result in kernel panic on reboot

If there were an alternate available in the base packages, that would make sense -- I did not see one.  There are very few programs among that ~100 package set which have equivalent functionality (grub and lilo coming to mind as the first).  For instance, there's no alternate to glibc, and if you forget to select it, the installer automatically adds it for you.  I don't think that's merely a case of dependencies (nearly every program would depend on glibc ), but if it is, feel free to correct me.

The kernel headers are some other packages seem to be "automatically" added, also.  I'm wondering a bit about how the installer works, but not desperately curious enough to dive into its internals to find out.

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#4 2007-09-10 07:51:16

klixon
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From: Nederland
Registered: 2007-01-17
Posts: 525

Re: Custom packages may result in kernel panic on reboot

all the kernels in current and extra have a dependency on mkinitcpio.
The only reason it would not be installed is if you installed a system and did not use one of the tried and tested stock-kernels (as is, you rolled your own)...

If you built your own kernel, you might have just copied the config from one of those stock kernel. This will not work without a proper initramfs...

An alternative would be to compile your own kernel and make your own config, in which you just the things you need and _not_ to compile these things as modules... This way you won't need an initramfs

If you did install a stock-kernel though, and you did it like so:

# pacman -S kernel26

(options: kernel26, kernel26ck, kernel26suspend), it would be a bug if mkinitcpio wasn't pulled in as a dependency

Are you sure mkinitcpio is not installed? What does

# pacman -Q | grep mkinitcpio

tell you?

Another possibility is that it is installed and you didn't have your boot-partition mounted when the initramfs wuold have been created...

Last edited by klixon (2007-09-10 07:53:33)


Stand back, intruder, or i'll blast you out of space! I am Klixon and I don't want any dealings with you human lifeforms. I'm a cyborg!

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#5 2007-09-12 00:23:58

kagerato
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Registered: 2007-09-10
Posts: 45
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Re: Custom packages may result in kernel panic on reboot

You're right; the kernel package does depend on mkinitcpio (and module-init-tools), among other things.  So that could not have been the problem.

I wasn't building a custom kernel.  Just installed the stock kernel26.  If I were building a custom kernel, I'd just include the root filesystem and mobo disk controller modules in the image itself, rather than use an initramfs or secondary load technique.

I've tried twice to reproduce the original kernel panic and have not managed to do so.  One thing I noticed while experimenting, though, is that if you forget to install gzip the console reports a failure in building the initramfs image (the ncurses installer interface still reports success, though -- so if you don't read the console output it is easily missed).  That may or may not be connected ...

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#6 2007-09-12 11:18:43

dolby
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From: 1992
Registered: 2006-08-08
Posts: 1,581

Re: Custom packages may result in kernel panic on reboot

ppl in general need to understand that the arch developers have chosen a certain way of doing things.
eg. when it comes to packages they try to built em , in most occasions, as vanilla as possible.
cause of the way arch works , the way i see it, it actually needs to be binary and "bleeding edge".
the arch system from what i can tell, resembles a configured in a certain way slackware.
if u dont like any of the above u are welcome to customise things to your needs if u want to but u'll have to do it yourself.
just like the above & about the kernel devs have chosen a certain path to follow.  IMHO its best to update the arch kernel normally and have it in your system and build and configure your own custom kernel to your needs.


There shouldn't be any reason to learn more editor types than emacs or vi -- mg (1)
[You learn that sarcasm does not often work well in international forums.  That is why we avoid it. -- ewaller (arch linux forum moderator)

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#7 2007-09-12 11:41:35

klixon
Member
From: Nederland
Registered: 2007-01-17
Posts: 525

Re: Custom packages may result in kernel panic on reboot

True, but...
it seems mkinitcpio is unable to function properly without gzip. Maybe mkinitcpio should have a gzip-dependency? Should we file a bug report?

Also, mkinitcpio's error-handling is a bit flakey. It sometimes fails to create a proper image, but reports success upon completion. I hope to be able to spend some time on that in the near future.
Have some personal probs to sort out first though... hmm


Stand back, intruder, or i'll blast you out of space! I am Klixon and I don't want any dealings with you human lifeforms. I'm a cyborg!

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