Difference between revisions of "How to compile kernel"
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| − | It should be noted that the default kernel that ships with Salix | + | It should be noted that the default kernel that ships with Salix will work in most cases, and no recompiling is necessary. You should only recompile if: |
* Your system's hardware is not supported by the default kernel | * Your system's hardware is not supported by the default kernel | ||
| Line 6: | Line 6: | ||
* For fun | * For fun | ||
| − | '''Before going ahead''', it may be easier (and will in many cases be sufficient to solve the problem) to install the kernel from Slackware current, which will always be relatively recent. | + | '''Before going ahead''', it may be easier (and will in many cases be sufficient to solve the problem) to [http://docs.salixos.org/wiki/How_to_install_a_different_kernel install the kernel from Slackware current], which will always be relatively recent. In some cases, you may wish to [http://docs.salixos.org/wiki/How_to_rebuild_the_Slackware_kernel_with_different_settings build the ''same'' kernel with different settings]. |
| − | The procedure is actually quite simple, as long as you remember to reinstall the bootloader before rebooting. However, it can take a long time | + | The procedure is actually quite simple, as long as you remember to reinstall the bootloader before rebooting. However, it can take a long time. |
== Preparation == | == Preparation == | ||
| − | First, download appropriate kernel source from http://www.kernel.org | + | First, download the appropriate kernel source from http://www.kernel.org |
| − | + | You will need the full kernel source tarball (the one with the tar.xz extension). | |
| − | + | ||
| − | + | Unpack source into a directory of your choosing (any directory will do, preferably somewhere in your home directory). | |
| − | + | Move to that directory, and do | |
make mrproper | make mrproper | ||
| Line 24: | Line 23: | ||
zcat /proc/config.gz > .config | zcat /proc/config.gz > .config | ||
| − | Next, you configure your kernel. The advantage of using the working configuration is you can | + | Next, you can configure your kernel. The advantage of using the working configuration as a starting-point is you can leave nearly all the options just as they are, but it may be that you need to turn on support for the hardware that doesn't work with the existing kernel; or it may work with the new kernel without changing anything at all. To build the kernel with the working configuration unchanged, do |
| − | + | ||
make oldconfig | make oldconfig | ||
| − | |||
If you do need to change anything, there is a choice of interfaces for the configuration. To use a graphical interface, do | If you do need to change anything, there is a choice of interfaces for the configuration. To use a graphical interface, do | ||
make gconfig | make gconfig | ||
| Line 41: | Line 38: | ||
Once you have configured the kernel to your liking, save and exit. Then do: | Once you have configured the kernel to your liking, save and exit. Then do: | ||
make | make | ||
| − | to build the kernel. This will take some hours. After it's done, do: | + | to build the kernel. This will take some hours... |
| − | make modules_install | + | |
| − | to install all of the modules. All of the modules will be installed under /lib/modules/version, where 'version' corresponds to the | + | == Installing == |
| + | After it's done, do: | ||
| + | sudo make modules_install | ||
| + | to install all of the modules. All of the modules will be installed under /lib/modules/version, where 'version' corresponds to the release number of the kernel compiled. | ||
| − | |||
Next, copy the created kernel image and system map to the boot directory. | Next, copy the created kernel image and system map to the boot directory. | ||
| − | cp -v arch/x86/boot/bzImage /boot/vmlinuz-version | + | sudo cp -v arch/x86/boot/bzImage /boot/vmlinuz-version |
| − | cp -v System.map /boot/System.map-version | + | sudo cp -v System.map /boot/System.map-version |
| − | where 'version' corresponds to the | + | where 'version' corresponds to the release number of the kernel compiled. |
Assuming the kernel in your working system is the standard one that came with Salix, the new one you just built will also be a 'huge' kernel that doesn't need an initrd, so you can omit the next step. | Assuming the kernel in your working system is the standard one that came with Salix, the new one you just built will also be a 'huge' kernel that doesn't need an initrd, so you can omit the next step. | ||
| + | == initrd == | ||
However, if you know you do need to create an initrd.gz file: | However, if you know you do need to create an initrd.gz file: | ||
/usr/share/mkinitrd/mkinitrd_command_generator.sh -l /boot/vmlinux-version | /usr/share/mkinitrd/mkinitrd_command_generator.sh -l /boot/vmlinux-version | ||
| − | will generate a mkinitrd command that you can then copy and paste. By default, it will output to /boot/initrd.gz. You may want to change this when cutting and pasting so that it will output to /boot/initrd-version.gz. Note that a suggested lilo stanza is also created, but the initrd itself is only made when you run the 'mkinitrd' command itself. | + | will generate a mkinitrd command that you can then copy and paste. By default, it will output to /boot/initrd.gz. You may want to change this when cutting and pasting so that it will output to /boot/initrd-version.gz. Note that a suggested lilo stanza is also created, but the initrd itself is only made when you run the 'mkinitrd' command itself. To do so, root privileges are required. |
| + | == Refresh LILO == | ||
As a final step, edit /etc/lilo.conf so that it will see the newly created kernel, including the 'initrd' line only if you created one: | As a final step, edit /etc/lilo.conf so that it will see the newly created kernel, including the 'initrd' line only if you created one: | ||
image = /boot/vmlinuz-version | image = /boot/vmlinuz-version | ||
| Line 65: | Line 66: | ||
Don't forget to run | Don't forget to run | ||
| − | lilo | + | sudo lilo |
to take effect of the new configuration; or use whichever tool you prefer to install the bootloader. | to take effect of the new configuration; or use whichever tool you prefer to install the bootloader. | ||
| Line 71: | Line 72: | ||
uname -a | uname -a | ||
| − | You should see that the kernel | + | You should see that the kernel release number is indeed the version you just built. |
The old kernel is still present, and your bootloader will still include an option to boot with it as a fallback. Once you are certain everything is working properly with the new one, you may wish to remove the old entry from the bootloader and (optionally, with care) delete the old kernel in /boot. | The old kernel is still present, and your bootloader will still include an option to boot with it as a fallback. Once you are certain everything is working properly with the new one, you may wish to remove the old entry from the bootloader and (optionally, with care) delete the old kernel in /boot. | ||
[[Category:User Documentation|Kernel]] | [[Category:User Documentation|Kernel]] | ||
Latest revision as of 19:49, 20 March 2014
It should be noted that the default kernel that ships with Salix will work in most cases, and no recompiling is necessary. You should only recompile if:
- Your system's hardware is not supported by the default kernel
- You need (want) features only available in newer kernel
- To get an extra fraction of a percent hardware performance
- For fun
Before going ahead, it may be easier (and will in many cases be sufficient to solve the problem) to install the kernel from Slackware current, which will always be relatively recent. In some cases, you may wish to build the same kernel with different settings.
The procedure is actually quite simple, as long as you remember to reinstall the bootloader before rebooting. However, it can take a long time.
Contents |
Preparation
First, download the appropriate kernel source from http://www.kernel.org
You will need the full kernel source tarball (the one with the tar.xz extension).
Unpack source into a directory of your choosing (any directory will do, preferably somewhere in your home directory).
Move to that directory, and do
make mrproper
This is a cleaning procedure and will set everything to default. You can work from here, but it is highly recommended to use the working configuration (i.e. the one you've been running on). The default kernel config is found in /proc/config.gz, so copy this file:
zcat /proc/config.gz > .config
Next, you can configure your kernel. The advantage of using the working configuration as a starting-point is you can leave nearly all the options just as they are, but it may be that you need to turn on support for the hardware that doesn't work with the existing kernel; or it may work with the new kernel without changing anything at all. To build the kernel with the working configuration unchanged, do
make oldconfig
If you do need to change anything, there is a choice of interfaces for the configuration. To use a graphical interface, do
make gconfig
for the gtk-based config, or on a KDE system
make xconfig
for a qt interface.
make menuconfig
will bring up the ncurses based menu-driven config, which will work even if you're not running X.
The number of different options may appear bewildering, but pretty much all of them can (indeed should) be left unchanged from the working configuration. If in doubt, as a rule of thumb, it is probably best to leave it as is.
Compiling
Once you have configured the kernel to your liking, save and exit. Then do:
make
to build the kernel. This will take some hours...
Installing
After it's done, do:
sudo make modules_install
to install all of the modules. All of the modules will be installed under /lib/modules/version, where 'version' corresponds to the release number of the kernel compiled.
Next, copy the created kernel image and system map to the boot directory.
sudo cp -v arch/x86/boot/bzImage /boot/vmlinuz-version sudo cp -v System.map /boot/System.map-version
where 'version' corresponds to the release number of the kernel compiled.
Assuming the kernel in your working system is the standard one that came with Salix, the new one you just built will also be a 'huge' kernel that doesn't need an initrd, so you can omit the next step.
initrd
However, if you know you do need to create an initrd.gz file:
/usr/share/mkinitrd/mkinitrd_command_generator.sh -l /boot/vmlinux-version
will generate a mkinitrd command that you can then copy and paste. By default, it will output to /boot/initrd.gz. You may want to change this when cutting and pasting so that it will output to /boot/initrd-version.gz. Note that a suggested lilo stanza is also created, but the initrd itself is only made when you run the 'mkinitrd' command itself. To do so, root privileges are required.
Refresh LILO
As a final step, edit /etc/lilo.conf so that it will see the newly created kernel, including the 'initrd' line only if you created one:
image = /boot/vmlinuz-version root = /dev/sda6 initrd = /boot/initrd-version.gz label = "New Kernel" read-only
Don't forget to run
sudo lilo
to take effect of the new configuration; or use whichever tool you prefer to install the bootloader.
That's it. When you reboot, you should see the new kernel in the lilo menu, and everything should work. As a check, after the system reboots itself:
uname -a
You should see that the kernel release number is indeed the version you just built.
The old kernel is still present, and your bootloader will still include an option to boot with it as a fallback. Once you are certain everything is working properly with the new one, you may wish to remove the old entry from the bootloader and (optionally, with care) delete the old kernel in /boot.
