Saturday, November 27, 2004

How to Compile 2.6 kernel for RedHat 8/9

STEP 1:
Download the latest version of the kernel and any patches. This documentation is done with linux-2.6.3, but look for later versions :
http://www.kernel.org/pub/linux/kernel/v2.6/
Also take a look at http://www.codemonkey.org.uk/post-halloween-2.5.txt
This has some useful hints on some of the changes needed.

STEP 2:
Download the latest version of module-init-tools "module-init-tools-3.0.tar.gz" and "modutils-2.4.21-23.src.rpm"
http://www.kernel.org/pub/linux/kernel/people/rusty/modules/module-init-tools-3.0.tar.gz http://www.kernel.org/pub/linux/kernel/people/rusty/modules/modutils-2.4.21-23.src.rpm

STEP 3:
Install module-init-tools. This will replace depmod [/sbin/depmod] and other tools.
tar -zxvf module-init-tools-3.0.tar.gz cd module-init-tools-3.0 ./configure --prefix=/sbin make make install ./generate-modprobe.conf /etc/modprobe.conf

STEP 4:
Install modutils-2.4.21-23.src.rpm. You may get warnings about user rusty and group rusty not existing. Also, yes, you'll have to force the install. If you don't do these steps for both Redhat 9 and Redhat 8, you'll have problems with the make modules_install.
rpm -i modutils-2.4.21-23.src.rpm rpmbuild -bb /usr/src/redhat/SPECS/modutils.spec rpm -Fi /usr/src/redhat/RPMS/i386/modutils-2.4.21-23.i386.rpm

STEP 5:
Install and configure the kernel. Do NOT use the /usr/src/linux area! Reference the README. I put my files in /home/src/kernel/
gunzip linux-2.6.3.tar.gz tar -xvf linux-2.6.3.tar cd linux-2.6.3
If you have patches install these now:
bzip2 -dc ../patch-2.6.xx.bz2 patch -p1

STEP 6:
Copy the appropriate /usr/src/linux-2.4/configs [kernel-2.4.20-i686.config, kernel-2.4.20-i686-smp.config] to .config in whatever directory you are installing. In my case it's /home/src/kernel/linux-2.6.3
cp /usr/src/linux-2.4/configs/kernel-2.4.20-i686.config \ /home/src/kernel/linux-2.6.3/.config
If you don't have the source configs, you can download them from here:
https://sourceforge.net/project/showfiles.php?group_id=79320&package_id=109944
I've also included a file config2.6-chirico which was a 2.6 version for some of my systems. This isn't a bad reference if you run into trouble.

STEP 7:
Assuming you copied the appropriate kernel-2.4 config to .config, run the following which will run through necessary questions for the 2.6 kernel. Or, you might want to use the config2.6-chirico...this has already been run through make oldconfig on my system, and I've answered the necessary questions for a general system.
make oldconfig

STEP 8:
This is very important. Make sure you're .config has the following in it CONFIG_EXT3_FS=y You'll run into the following error if you leave this =m instead of =y:
pivotroot: pivot_root(/sysroot,/sysroot/initrd) failed
This is because Redhat 9.0 and 8.0 use the ext3 filesystem for /boot ...

STEP 9:
Edit the Makefile and add changes to the Extraversion as desired. Patches will update these values as well.
VERSION = 2 PATCHLEVEL = 6 SUBLEVEL = 3 EXTRAVERSION = -skim-ch6

STEP 10:
make bzImage

STEP 11:
make modules

STEP 12:
make modules_install

STEP 13:
make install
If you come across errors here, what version of "depmod" is being picked up in your path?
Also, if you get a module not found, say the following: No module aic7xxx found for kernel 2.6.x Then, in /lib/modules/2.6.x/kernel/drivers/scsi/aic7xxx/ cp aic7xxx.ko aic7xxx.o
insmod should look for aic7xxx.ko ;but , it looks for aic7xxx.o
If you still have trouble, make the following change in the .config CONFIG_BLK_DEV_SD=y and go back to STEP 10.
You also may want to ref kernel-2.6.3-i686-smp-chirico-aic7xxx.config inhttp://prdownloads.sourceforge.net/souptonuts/configs-0.3.tar.gz?download

STEP 14:
mkdir /sys

STEP 15:
/etc/rc.sysinit needs to be modified. Look for the following line:
action $"Mounting proc filesystem: " mount -n -t proc /proc /proc
and after this line enter the following:
action $"Mounting sysfs filesystem: " mount -t sysfs none /sys
Here's my /etc/rc.sysinit for reference:
http://prdownloads.sourceforge.net/souptonuts/rc.sysinit.txt?download

Be very careful at this step. Backup the /etc/rc.sysinit file.
Thomer [http://thomer.com/linux/migrate-to-2.6.html ] also added changes to /etc/fstab. I only had to do STEP 16 below.

STEP 16:
Add the following to /etc/fstab for usb support.
/proc/bus/usb /proc/bus/usb usbdevfs defaults 0 0

STEP 17 (CHECKING EVERYTHING):
Check the following:
a. The new image file should be installed on boot and there should be sym link to it. My latest kernel is 2.6.3-skim-ch6, and I got the "-skim-ch6" from the values I put in the Makefile, so I see the following:
/boot vmlinuz -> vmlinuz-2.6.3-skim-ch6 System.map -> System.map-2.6.3-skim-ch6
/boot/grub/grub.conf Should have been automatically updated from make.
In /boot/grub/grub.conf change "default=0" to boot with the new kernel. Here's an example of my grub.conf:
# grub.conf generated by anaconda # # Note that you do not have to rerun grub after making # NOTICE: You have a /boot partition. This means that # all kernel and initrd paths are relative to # root (hd0,2) # kernel /vmlinuz-version ro root=/dev/hda6 # initrd /initrd-version.img #boot=/dev/hda default=0 timeout=10 splashimage=(hd0,2)/grub/splash.xpm.gz title Red Hat Linux (2.6.3-skim-ch6) root (hd0,2) kernel /vmlinuz-2.6.3-skim-ch6 ro root=LABEL=/ initrd /initrd-2.6.3-skim-ch6.img
b. The directory /sys exists
c. You added the mount command for sys in /etc/rc.sysinit
d. CONFIG_EXT3_FS=y was used in the .config
e. Run /sbin/lsmod or cat /proc/modules to make sure a 2.4 kernel module wasn't forgotten. Also look at "$cat /proc/iomem"

STEP 18 (DEVELOP YOUR OWN 2.6 MODULES):
You're done with the 2.6 build. So learn how to develop 2.6 kernel modules. First, checkout the following article
http://lwn.net/Articles/driver-porting/
Then, take a look at the following sample code, which shows how to create /proc entries for communicating with the kernel and writing out to any available tty device.
http://prdownloads.sourceforge.net/souptonuts/procreadwrite.0.0.1a.tar.gz?download

REFERENCES:
http://www.codemonkey.org.uk/post-halloween-2.5.txthttp://kerneltrap.org/node/view/799http://thomer.com/linux/migrate-to-2.6.html http://www.kernel.org/
http://bugzilla.kernel.org/http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&group=linux.kernelhttp://linuxdevices.com/articles/AT3855888078.html
http://prdownloads.sourceforge.net/souptonuts/README_26.txt?downloadhttp://prdownloads.sourceforge.net/souptonuts/rc.sysinit.txt?downloadhttp://prdownloads.sourceforge.net/souptonuts/configs-0.3.tar.gz?downloadhttps://sourceforge.net/forum/forum.php?forum_id=353715
http://www.redhat.com/software/rhel/kernel26/http://www.tldp.org/HOWTO/KernelAnalysis-HOWTO.htmlhttp://www-124.ibm.com/linux/projects/?topic_id=2
KERNEL DRIVER DEVELOPMENT IN 2.6:
Excellent (series of articles): http://lwn.net/Articles/driver-porting/
Here's my sample program: http://prdownloads.sourceforge.net/cpearls/procreadwrite.0.0.1a.tar.gz?download
Good but dated for 2.4 kernel: http://www.oreilly.com/catalog/linuxdrive2/
http://linuxdevices.com/articles/AT4389927951.html http://linuxdevices.com/articles/AT5793467888.html

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