diff options
Diffstat (limited to 'chapter_19.xml')
| -rw-r--r-- | chapter_19.xml | 171 |
1 files changed, 110 insertions, 61 deletions
diff --git a/chapter_19.xml b/chapter_19.xml index bc49aed..e819fe5 100644 --- a/chapter_19.xml +++ b/chapter_19.xml @@ -5,7 +5,7 @@ <chapter> <title>The Linux Kernel</title> -<section> +<section id="ch_kernel"> <title>What Does the Kernel Do?</title> <para> @@ -26,9 +26,18 @@ of software on your computer and the most complex. </section> -<section> +<section id="kernel_modules"> <title>Working with Modules</title> +<indexterm> + <primary>kernel</primary> + <secondary>modules</secondary> +</indexterm> + +<indexterm> +<primary>modules</primary> +</indexterm> + <para> The complexity of a modern linux kernel is staggering. The source code for the kernel weighs in at nearly 400MB uncompressed. There are @@ -49,11 +58,15 @@ It's important to realize that Slackware will automatically handle loading most modules for you. When your system boots, <application>udevd</application>(8) is started and begins to probe your system's hardware. For each device it finds, it loads the proper module -and created a device node in <filename>/dev</filename>. This usually +and created a device node in <filename>/dev</filename>. This usually means that you will not need to load any modules in order to use your computer, but occasionally this is necessary. </para> +<indexterm> + <primary>lsmod</primary> +</indexterm> + <para> So what modules are currently loaded on your computer and how do we load and unload them? Fortunately we have a full suite of tools for @@ -61,7 +74,7 @@ handling this. As you might have guessed, the tool for listing modules is <application>lsmod</application>(8). </para> -<screen><prompt>darkstar:~# </prompt><userinput>lsmod</userinput> +<screen><prompt>darkstar:~# </prompt><userinput>lsmod</userinput> Module Size Used by nls_utf8 1952 1 cifs 240600 2 @@ -77,6 +90,13 @@ In addition to showing you what modules are loaded, it displays the size of each module and tells you what other modules are using it. </para> +<indexterm> + <primary>modprobe</primary> +</indexterm> +<indexterm> + <primary>insmod</primary> +</indexterm> + <para> There are two applications for loading modules: <application>insmod</application>(8) and @@ -87,9 +107,9 @@ preferred because it can load any module dependencies. Using either is straight-forward. </para> -<screen><prompt>darkstar:~# </prompt><userinput>insmod ext3</userinput> -<prompt>darkstar:~# </prompt><userinput>modprobe ext4</userinput> -<prompt>darkstar:~# </prompt><userinput>lsmod | grep ext</userinput> +<screen><prompt>darkstar:~# </prompt><userinput>insmod ext3</userinput> +<prompt>darkstar:~# </prompt><userinput>modprobe ext4</userinput> +<prompt>darkstar:~# </prompt><userinput>lsmod | grep ext</userinput> ext4 239928 1 jbd2 59088 1 ext4 crc16 1984 1 ext4 @@ -98,6 +118,10 @@ jbd 48520 1 ext3 mbcache 8068 2 ext4,ext3 </screen> +<indexterm> + <primary>rmmod</primary> +</indexterm> + <para> Removing modules can be a tricky process, and once again we have two programs for removing them: <application>rmmod</application>(8) and @@ -105,49 +129,61 @@ programs for removing them: <application>rmmod</application>(8) and modprobe, you'll need to use the <arg>-r</arg> argument. </para> -<screen><prompt>darkstar:~# </prompt><userinput>rmmod ext3</userinput> -<prompt>darkstar:~# </prompt><userinput>modprobe -r ext4</userinput> -<prompt>darkstar:~# </prompt><userinput>lsmod | grep ext</userinput> +<screen><prompt>darkstar:~# </prompt><userinput>rmmod ext3</userinput> +<prompt>darkstar:~# </prompt><userinput>modprobe -r ext4</userinput> +<prompt>darkstar:~# </prompt><userinput>lsmod | grep ext</userinput> </screen> </section> -<section> +<section id="kernel_compile"> <title>Compiling A Kernel and Why to do So</title> +<indexterm> + <primary>kernel</primary> + <secondary>compiling</secondary> +</indexterm> + <para> Most Slackware users will never need to compile a kernel. The huge and generic kernels contain virtually all the support you will need. +</para> + +<para> However, some users may need to compile a kernel. If your computer contains bleeding edge hardware, a newer kernel may offer improved support. Sometimes a kernel patch my be available that corrects a problem you are experiencing. In these cases a kernel compile is -probably warranted. Users who simply want the latest and greatest +probably warranted. Users who simply want the latest and greatest version or who believe using a custom compiled kernel will give them -greater performance can certainly upgrade, but are unlikely to notice -any major changes. If you still think compiling your own kernel is -something you want or need to do, this section should walk you through -the many steps. +greater performance can certainly upgrade, but are unlikely to +actually notice any major changes. +</para> + +<para> +If you still think compiling your own kernel is something you want or +need to do, this section should walk you through the many steps. Compiling and installing a kernel is not that difficult, but there are a number of mistakes that can be made along the way, many of which can prevent your computer from booting and cause major frustration. </para> <para> -The first step is ensuring you have the kernel source code installed on -your system. The kernel source package is included in the "k" disk set -in the Slackware installer, or you can download another version from -<ulink url="http://www.kernel.org/">http://www.kernel.org/</ulink>. +The first step is ensuring you have the kernel source code installed +on your system. The kernel source package is included in the +"k" disk set in the Slackware installer, or you can download +another version from <ulink +url="http://www.kernel.org/">http://www.kernel.org/</ulink>. Traditionally, the kernel source is located in -<filename>/usr/src/linux</filename>, a symbolic link that points to the -specific kernel release used, but this is by no means set in stone. You -can place the kernel source code virtually anywhere without -encountering any problems. +<filename>/usr/src/linux</filename>, a symbolic link that +points to the specific kernel release used, but this is by no means +set in stone. You can place the kernel source code virtually anywhere +without encountering any problems. </para> -<screen><prompt>darkstar:~# </prompt><userinput>ls -l /usr/src</userinput> -lrwxrwxrwx 1 root root 14 2009-07-22 19:59 linux -> linux-2.6.29.6/ -drwxr-xr-x 23 root root 4096 2010-03-17 19:00 linux-2.6.29.6/ +<screen><prompt>darkstar:~# </prompt><userinput>ls -l /usr/src</userinput> +lrwxrwxrwx 1 root root 14 2009-07-22 19:59 linux -> linux-2.6.29.6/ +drwxr-xr-x 23 root root 4096 2010-03-17 19:00 linux-2.6.29.6/ </screen> <para> @@ -170,14 +206,14 @@ compile the kernel again and again until you get it right. The best kernel <filename>.config</filename> files to start with are those used by Slackware's default kernels. You can find them on your Slackware install disks or at your favorite mirror in the -<filename>kernels/</filename> directory. +<filename>kernels/</filename> directory. </para> -<screen><prompt>darkstar:~# </prompt><userinput>mount /mnt/cdrom</userinput> -<prompt>darkstar:~# </prompt><userinput>cd /mnt/cdrom/kernels</userinput> -<prompt>darkstar:/mnt/cdrom/kernels# </prompt><userinput>ls</userinput> -VERSIONS.TXT huge.s/ generic.s/ speakup.s/ -<prompt>darkstar:/mnt/cdrom/kernels# </prompt><userinput>ls genric.s</userinput> +<screen><prompt>darkstar:~# </prompt><userinput>mount /mnt/cdrom</userinput> +<prompt>darkstar:~# </prompt><userinput>cd /mnt/cdrom/kernels</userinput> +<prompt>darkstar:/mnt/cdrom/kernels# </prompt><userinput>ls</userinput> +VERSIONS.TXT huge.s/ generic.s/ speakup.s/ +<prompt>darkstar:/mnt/cdrom/kernels# </prompt><userinput>ls genric.s</userinput> System.map.gz bzImage config </screen> @@ -191,26 +227,29 @@ and thus creates a smaller kernel image, but it usually requires the use of an initrd. </para> -<screen><prompt>darkstar:/mnt/cdrom/kernels# </prompt><userinput>cp generic.s/config /usr/src/linux/.config</userinput> +<screen><prompt>darkstar:/mnt/cdrom/kernels# </prompt><userinput>cp generic.s/config /usr/src/linux/.config</userinput> </screen> -<note><para> -The Slackware kernel file lacks the "dot" while the kernel -file includes it. If you forget, or simply copy the -<filename>config</filename> to <filename>/usr/src</filename> whatever -<filename>.config</filename> file was already present will be used -instead. -</para></note> +<important> + <para> + The Slackware kernel file lacks the "dot" while the kernel file + includes it. If you forget, or simply copy the + <filename>config</filename> to + <filename>/usr/src</filename> whatever + <filename>.config</filename> file was already present will be used + instead. +</para> +</important> <para> If you want to use the configuration for the currently running kernel as your base, you may be able to locate it at -<filename>/proc/config.gz</filename>. This is a special kernel-related +<filename>/proc/config.gz</filename>. This is a special kernel-related file that includes the entire kernel configuration in a compressed format and requires that your kernel was built to support it. </para> -<screen><prompt>darkstar:~# </prompt><userinput>zcat /proc/config.gz > /usr/src/linux/.config</userinput> +<screen><prompt>darkstar:~# </prompt><userinput>zcat /proc/config.gz > /usr/src/linux/.config</userinput> </screen> <para> @@ -230,14 +269,14 @@ options. Since options are added at virtually every kernel release, this is generally a good thing to do. </para> -<screen><prompt>darkstar:/usr/src/linux# </prompt><userinput>make oldconfig</userinput> -scripts/kconfig/conf -o arch/x86/Kconfig -* -* Restart config... -* -* -* File systems -* +<screen><prompt>darkstar:/usr/src/linux# </prompt><userinput>make oldconfig</userinput> +scripts/kconfig/conf -o arch/x86/Kconfig +* +* Restart config... +* +* +* File systems +* Second extended fs support (EXT2_FS) [M/n/y/?] m Ext2 extended attributes (EXT2_FS_XATTR) [N/y/?] n Ext2 execute in place support (EXT2_FS_XIP) [N/y/?] n @@ -281,6 +320,11 @@ Automatically append version information to the version string (LOCALVERSION_AUT Support for paging of anonymous memory (swap) (SWAP) [Y/n/?] </screen> +<indexterm> + <primary>kernel</primary> + <secondary>menuconfig</secondary> +</indexterm> + <para> Fortunately, there are two much easier ways to configure your kernel, <arg>menuconfig</arg> and <arg>xconfig</arg>. Both of these create a @@ -302,13 +346,16 @@ the arrow keys. <imagedata fileref="img/make-menuconfig-w.png" format="PNG"/> -<warning><para> -If you are compiling a kernel that is the same release as the stock -Slackware kernel, you must set the "Local version" option. This is -found on the "General setup" submenu. Failure to set this will result -in your kernel compile over-writing all the modules used by the stock -kernels. This can quickly render your system unbootable. -</para></warning> +<warning> + <para> + If you are compiling a kernel that is the same release as the + stock Slackware kernel, you must set the "Local version" + option. This is found on the "General setup" submenu. Failure to + set this will result in your kernel compile over-writing all the + modules used by the stock kernels. This can quickly render your + system unbootable. + </para> +</warning> <para> Once you've finished configuring the kernel, it's time to begin @@ -339,7 +386,8 @@ configuration first. Compile errors are usually caused by a fault we're still not entirely finished, as we need to build the modules. </para> -<screen><prompt>darkstar:/usr/src/linux# </prompt><userinput>make modules</userinput> +<screen> +<prompt>darkstar:/usr/src/linux# </prompt><userinput>make modules</userinput> CHK include/linux/version.h CHK include/linux/utsrelease.h SYMLINK include/asm -> include/asm-x86 @@ -358,8 +406,9 @@ images located there. Traditionaly kernel images are named appended. </para> -<screen><prompt>darkstar:/usr/src/linux# </prompt><userinput>cat arch/x86/boot/bzImage > /boot/vmlinuz-release_number-local_version</userinput> -<prompt>darkstar:/usr/src/linux# </prompt><userinput>make modules_install</userinput> +<screen> + <prompt>darkstar:/usr/src/linux# </prompt><userinput>cat arch/x86/boot/bzImage > /boot/vmlinuz-release_number-local_version</userinput> + <prompt>darkstar:/usr/src/linux# </prompt><userinput>make modules_install</userinput> </screen> <para> |