Kernel compile and install for newbies

[Stian1979]

Sure you've gotten the initrd part right?

Not suposed to have initrd on a initrd free kernel.
With initrd I got no problems.

[kanonmat]

I compiled, rebooted and got a kernel panic. What's the approach to find what's wrong? As hazel posted, there is so much stuff in the kernel that I won't ever use. (I removed what I thought unnecessary and among other things changed timer frequency to 1000Hz and set voluntary kernel preemption.) Just changing one item at a time, compile for an hour and reboot feels very inefficient.

[Stian1979]

I compiled, rebooted and got a kernel panic. What's the approach to find what's wrong? As hazel posted, there is so much stuff in the kernel that I won't ever use. (I removed what I thought unnecessary and among other things changed timer frequency to 1000Hz and set voluntary kernel preemption.) Just changing one item at a time, compile for an hour and reboot feels very inefficient.

Do you have a initrd for that kernel? for some reason it's not created automatically anymore.

[kanonmat]

***TOTAL EDIT OF POST***
No, I didn't get an initrd. I'm using sid.
I read dbboltons post above, but I didnt follow the link I was trying to figure out why I couldn't boot with the new kernel, keeping myself busy trying to generate initrds and writing a lengthy post. Its shorter now.

Kernel panicked with this:

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no filesystem could mount root, tried:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

It wouldn't boot with an initrd borrowed from the other kernel. (The vanilla kernel wouldn't boot without an initrd either.) Maybe I don't need an initrd, a guru on irc said it was unnecessary. I guess I need to move some of the stuff that the initrd does to the kernel. What and how?

I cant see whats in the initrd. "file initrd.img-2.6.30-1-amd64" says its a gzip, but i can't gunzip it. What is it? I read in some post on a mailinglist from around 2003 that the debian initrd uses cramfs. This fails anyway:

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mount -o loop -t cramfs initrd.img-2.6.30-1-amd64 tmp/

***TOTAL EDIT OF POST***

[dbbolton]

Maybe I don't need an initrd, a guru on irc said it was unnecessary. I guess I need to move some of the stuff thats in the initrd to the kernel. The questions are: what and how?

You will need drivers for your hard disk (IDE/SATA) as well as drivers for your root filesystem build into the kernel (*), not as modules (m).

If you just want to fix the initrd for the new kernel, see the link I posted above.

[hazel]

If you're using sid, you have a later kernel than I do. Apparently some of these recent kernels don't use the traditional hd*/sd* distinction; they put all the hard drives in the sd* series. So if your grub menu gives the root partition as /dev/hda*, the kernel won't be able to find it.

The official Debian solution to this is to use the UUID of the partition rather than a device file but I found out the hard way that this doesn't work without an initrd. So if you've got /dev/hda* in your grub menu, it might be worth editing it to /dev/sda* and see if that makes a difference.

PS: Why should I write a howto? We've got a perfectly good one in this thread already.

[Tadeas]

I've just compiled 2.6.31-rc9 and I've encountered two problems. I post here the solution if anybody is interested...

First, the compilation fails with missing zlib.h library. This is probably a bug in kernel-package that it doesn't depend on it. Anyway, you need to install zlib1g-dev package.

Second, the --initrd parameter to make-kpkg didn't create initrd. You create it with this command in /boot after you have installed the kernel .deb:
# mkinitramfs -oinitrd-2.6.31-rc9 2.6.31-rc9
Run dpkg-reconfigure grub-pc if you use grub2 or dpkg-reconfigure grub-legacy (or whatever is the grub1 package) to notify grub of the new initrd.

Hope this helps anybody .

[milomak]

The initrd issue can be solved using the solution in this post

i copied the initramfs-tools script and the initrd is created when i install using dpkg.

[jalu]

i followed the how-to in the first post, step by step, but changed some things according to the advices given later in this thread:
i get this error massage :

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/usr/bin/make  EXTRAVERSION=jalu  ARCH=i386 \
			     -C Documentation/lguest
make[1]: Entering directory `/home/jalu/Kernel/linux-2.6-2.6.26/Documentation/lguest'
cc -Wall -Wmissing-declarations -Wmissing-prototypes -O3 -I../../include    lguest.c  -lz -o lguest
lguest.c:34:18: error: zlib.h: No such file or directory
make[1]: *** [lguest] Error 1

after running this command:

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 fakeroot make-kpkg --append-to-version "jalu" --revision "090909" --initrd kernel_image kernel_headers

i dont know what im doing wrong here (about append-to-version and revision im pretty unsure...)

----
[
i also followed this howto:
http://wiki.debian.org/HowToRebuildAnOf ... nelPackage
but changed some things according to my book (as i didnt understand everything).
There i had to to add a "revision-thingy" to those files:
/home/jalu/Kernel/linux-2.6-2.6.26/debian{changelog,config/defines}
That build went thru (but wasnt known by the package-system afterwards).
]


greetings

[garrincha]

i followed the how-to in the first post, step by step, but changed some things according to the advices given later in this thread:
i get this error massage :

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/usr/bin/make  EXTRAVERSION=jalu  ARCH=i386 \
			     -C Documentation/lguest
make[1]: Entering directory `/home/jalu/Kernel/linux-2.6-2.6.26/Documentation/lguest'
cc -Wall -Wmissing-declarations -Wmissing-prototypes -O3 -I../../include    lguest.c  -lz -o lguest
lguest.c:34:18: error: zlib.h: No such file or directory
make[1]: *** [lguest] Error 1

You're getting zlib error, something that I never got before. Anyway, check the 1st post on this very trend by Rolling Stone, near bottom:

Troubleshooting:

If you get an error about missing zlib.h, make sure you have these packages installed

[jalu]

thanks, its running again and will take some hours.

[jalu]

that was the problem. the build went through this time.
but when i booted i ran into kernel-panic/not syncing.
(entries in menu.lst are ok, but i tried by-id too).

two things come in my mind: a) its in virtualbox b) i didnt run oldconfig or copied the /boot/config* over but went straight for a make menuconfig.

well, i`ll try it once again under different conditions.
-
no luck:
still kernel panic, different error:
kernel-panic not syncing; VFS Unable to mount root fs; unknown block.
search gave me: a) grub-entry is wrong (its correct)
b) driver for root system is not build into the kernel ( i thought thats why theres an initrd?)

How come that with an
make modules_install
make install
it did work, but not with the fakeroot make-kpkg*** ?

[jalu]

take that:
i mv /lib/modules/{2.6.30-1-686, 2.6.30-1-686_old}
no luck
i removed the deb via apt-get remove --purge
i cd into the source directory /home/jalu/Kernel/2.6.30
make modules_install
make install
update-initramfs -c -k 2.6.30-mt
update grub

Make install didnt build, but was finished within the blink of an eye.
The kernel is up and running now.

How come?

[garrincha]

Make install didnt build, but was finished within the blink of an eye.
The kernel is up and running now.

How come?

I'm not sure as I'm somewhat unfamiliar with what you're doing. In any case if your kernel panic, check to make sure that menu.lst entry is correct including the initrd entry:

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title           Debian GNU/Linux, kernel 2.6.30.5 (verbose splash) on /dev/sda6
root            (hd0,5)
kernel          /boot/vmlinuz-2.6.30.5 root=/dev/sda6 ro
initrd          /boot/initrd.img-2.6.30.5

[jalu]

menu.lst entry is/was correct (if im not more nut than usual). I checked different times. I even re-installed to make sure its not a borked system (ex-live-cd; installed with mint-installer, *-table not in order any more).

i think this evening or tomorrow i`ll go for a hard-disk run. As long as that works all is fine.

[jalu]

just a curious question. on this side
http://wiki.debian.org/HowToRebuildAnOf ... nelPackage
it is said one should run an:

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apt-get build-dep linux-2.6

but no one seems to mention it over here. I guess the answer is simple

[Rolling Stone]

That command should pull in and install the dependancies for the package linux-2.6. Basically the first step in my guide. It's handy if it works. I haven't tried it myself (while compiling a kernel) and don't know what packages it would get.

[jalu]

That command should pull in and install the dependancies for the package linux-2.6. Basically the first step in my guide. It's handy if it works. I haven't tried it myself (while compiling a kernel) and don't know what packages it would get.

thats something i would have expected or understood. but after installing the apps you mentioned above apt-get build-dep linux-2.6 did install other stuff too (if im correct yesterday, on sid, it has been 350MB, and today, on lenny, it has been only 17MB)

as no-one mentions it over here i guess it does mean nothing.

btw: nice how-to, gave me hope and, with a big bunch of help, it did work.
greetings

[nadir]

a short question:
after installing the deb`s i got the source*tar.bz2 in /usr/src and in my ~/Kernel. Additionally i got the linux-source and the two debs in my ~/Kernel.
do i need to keep them? ok, i think the bz2`s and the deb`s i may remove safely, what about the linux-source (once i`ve linked /lib/modules... to /usr/src...). thanks.

[Telemachus]

a short question:
after installing the deb`s i got the source*tar.bz2 in /usr/src and in my ~/Kernel. Additionally i got the linux-source and the two debs in my ~/Kernel.
do i need to keep them? ok, i think the bz2`s and the deb`s i may remove safely, what about the linux-source (once i`ve linked /lib/modules... to /usr/src). thanks.

I apologize, but I haven't been following. So sorry if this is behind the times. You don't need (ever) to have the source in /usr/src, and in general the modern default is not to put source there (or build there). Do it in your home directory. (Doesn't mean you have to agree, but I think it's the norm now, and it makes a lot of sense to me.)

I always throw out the debs (they're installed, don't need extras), but keep the unzipped source and the original zipped source - at least for the latest kernel. I don't link anything to /usr/src, so I want to keep the sources I built against. I keep the clean source just in case I end up wanting to rebuild from scratch. At the end of the day, even 100 or 200 MB of source files aren't really that much space on a modern drive.