Linux kernel
The kernel is the core piece of the Linux operating system.
- Current (stable version): 3.4.6 (2012-07-19)
Contents
Resources
The kernel manages the resources of the Linux OS; such as the following:
- File management
- Multitasking
- Memory management
- I/O management
- Process management:
/proc/ - Device management:
/dev/ - Networking support (including IPv4 and IPv6)
- Virtual memory, shared libraries, demand loading, etc.
The kernel decides who will use these resources, for how long, and when.
Rebuilding kernel from SRPM
Note: some of the paths below include $TOPDIR, which is distribution-dependent and can be further redefined by user. To find out the proper location on your system, issue this command:
rpm --eval "%{_topdir}"
openSUSE 10.2 returns:
/usr/src/packages
Mandriva Linux 2007.1 returns:
/usr/src/rpm
Example kernel update protocol
For this example, I will be using Mandriva Linux and updating/upgrading from kernel kernel-smp-2.6.8.1.12mdk-1-1mdk to kernel-smp-2.6.12.31mdk-1-1mdk.
The first thing you should do before updating your kernel is to backup your /sbin/*25 files (some distributions omit the "-25" at the end of each name) to a floppy disc (handy for quickly restoring them). These would include:
/sbin/depmod-25 /sbin/insmod-25 /sbin/lsmod-25 /sbin/modinfo-25 /sbin/modprobe-25 /sbin/rmmod-25
It wouldn't hurt to also backup your entire /etc directory.
Then, update your old kernel's related rpms:
rpm -Uvh fbgrab-1.0-1mdv2007.0.i586.rpm rpm -Uvh libgtk-linux-fb-2.0_0-2.4.14-6mdk.i586.rpm rpm -Uvh bootsplash-3.1.12-0.2.20060mdk.i586.rpm rpm -Uvh mkinitrd-4.2.17-17.2.20060mdk.i586.rpm rpm -Uvh module-init-tools-3.2-0.pre8.2.1.20060mdk.i586.rpm rpm -Uvh aumix-text-2.8-12mdk.i586.rpm rpm -Uvh sound-scripts-0.35-1mdk.noarch.rpm rpm -Uvh hotplug-2004_09_23-7mdk.i586.rpm # Returns clashing dependencies (possible problem source): #rpm -Uvh udev-068-34mdk.i586.rpm
Now, install (not "upgrade") your new kernel rpm:
# Note: I am NOT using "rpm -Uvh", as I wish to _keep_ the old kernel # The "smp" RPM is for multi-processor systems rpm -ivh kernel-smp-2.6.12.31mdk-1-1mdk.i586.rpm
Notes:
# Linux kernel RPM: # - kernel (/boot/vmlinux-2.X.XX-X); # - modules (/lib/modules/2.X.XX-X/...); # - /boot/System.map-2.X.XX-X; and # - /boot/module-info-2.X.XX-X
Now, create the initrd image:
/sbin/mkinitrd /boot/initrd-2.6.12.31mdksmp.img 2.6.12.31mdk-1-1mdk
Edit /etc/lilo.conf and add new/old kernel boots (you want to keep your old kernel, just in case anything goes wrong you can boot your old, working kernel). For an example,
image=/boot/vmlinuz-2.6.12-31mdksmp
label="linux-2.6.12-31mdksmp"
root=/dev/sda1
initrd=/boot/initrd-2.6.12-31mdksmp.img
append="acpi=ht resume=/dev/sda5 splash=silent"
vga=788
read-only
image=/boot/vmlinuz-2.6.8.1-12mdksmp
label="linux-2.6.8.1-12mdksmp"
root=/dev/sda1
initrd=/boot/initrd-2.6.8.1-12mdksmp.img
append="acpi=ht resume=/dev/sda5 splash=silent"
vga=788
read-only
Now commit the changes to lilo:
lilo -v
Reboot:
shutdown -r now
And that should do it.
Possible problems/fixes
If you have problems with any kernel (old, new, or both), here are some possible troubleshooting steps you can take:
- Boot in a rescue disk (e.g. Mandrake 10.1 installation CD)
- Restore your old
/sbin/*25files from the floppy disc (see above) - Check to make sure your
/etc/lilo.confis pointing to the correct kernels and images. - Then, try rebooting.
Kernel files
Note: These files are found in the /boot directory.
| Kernel files | ||
|---|---|---|
| Distribution | Kernel file | Ram disk |
| SuSE | linux |
initrd
|
| Mandriva | vmlinuz |
all.rdz
|
| Fedora | vmlinuz |
initrd.img
|
| Knoppix | vmlinuz |
initrd.img
|
| Slackware | bzImage |
initrd.img
|
| Ubuntu | vmlinuz |
initrd.gz
|
| Gentoo | gentoo |
gentoo.igz
|
| Debian | vmlinuz |
initrd.gz
|
