| Linux kernel release 3.x <http://kernel.org/> | |
| These are the release notes for Linux version 3. Read them carefully, | |
| as they tell you what this is all about, explain how to install the | |
| kernel, and what to do if something goes wrong. | |
| WHAT IS LINUX? | |
| Linux is a clone of the operating system Unix, written from scratch by | |
| Linus Torvalds with assistance from a loosely-knit team of hackers across | |
| the Net. It aims towards POSIX and Single UNIX Specification compliance. | |
| It has all the features you would expect in a modern fully-fledged Unix, | |
| including true multitasking, virtual memory, shared libraries, demand | |
| loading, shared copy-on-write executables, proper memory management, | |
| and multistack networking including IPv4 and IPv6. | |
| It is distributed under the GNU General Public License - see the | |
| accompanying COPYING file for more details. | |
| ON WHAT HARDWARE DOES IT RUN? | |
| Although originally developed first for 32-bit x86-based PCs (386 or higher), | |
| today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and | |
| UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell, | |
| IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS, | |
| Xtensa, Tilera TILE, AVR32 and Renesas M32R architectures. | |
| Linux is easily portable to most general-purpose 32- or 64-bit architectures | |
| as long as they have a paged memory management unit (PMMU) and a port of the | |
| GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has | |
| also been ported to a number of architectures without a PMMU, although | |
| functionality is then obviously somewhat limited. | |
| Linux has also been ported to itself. You can now run the kernel as a | |
| userspace application - this is called UserMode Linux (UML). | |
| DOCUMENTATION: | |
| - There is a lot of documentation available both in electronic form on | |
| the Internet and in books, both Linux-specific and pertaining to | |
| general UNIX questions. I'd recommend looking into the documentation | |
| subdirectories on any Linux FTP site for the LDP (Linux Documentation | |
| Project) books. This README is not meant to be documentation on the | |
| system: there are much better sources available. | |
| - There are various README files in the Documentation/ subdirectory: | |
| these typically contain kernel-specific installation notes for some | |
| drivers for example. See Documentation/00-INDEX for a list of what | |
| is contained in each file. Please read the Changes file, as it | |
| contains information about the problems, which may result by upgrading | |
| your kernel. | |
| - The Documentation/DocBook/ subdirectory contains several guides for | |
| kernel developers and users. These guides can be rendered in a | |
| number of formats: PostScript (.ps), PDF, HTML, & man-pages, among others. | |
| After installation, "make psdocs", "make pdfdocs", "make htmldocs", | |
| or "make mandocs" will render the documentation in the requested format. | |
| INSTALLING the kernel source: | |
| - If you install the full sources, put the kernel tarball in a | |
| directory where you have permissions (eg. your home directory) and | |
| unpack it: | |
| gzip -cd linux-3.X.tar.gz | tar xvf - | |
| or | |
| bzip2 -dc linux-3.X.tar.bz2 | tar xvf - | |
| Replace "X" with the version number of the latest kernel. | |
| Do NOT use the /usr/src/linux area! This area has a (usually | |
| incomplete) set of kernel headers that are used by the library header | |
| files. They should match the library, and not get messed up by | |
| whatever the kernel-du-jour happens to be. | |
| - You can also upgrade between 3.x releases by patching. Patches are | |
| distributed in the traditional gzip and the newer bzip2 format. To | |
| install by patching, get all the newer patch files, enter the | |
| top level directory of the kernel source (linux-3.X) and execute: | |
| gzip -cd ../patch-3.x.gz | patch -p1 | |
| or | |
| bzip2 -dc ../patch-3.x.bz2 | patch -p1 | |
| Replace "x" for all versions bigger than the version "X" of your current | |
| source tree, _in_order_, and you should be ok. You may want to remove | |
| the backup files (some-file-name~ or some-file-name.orig), and make sure | |
| that there are no failed patches (some-file-name# or some-file-name.rej). | |
| If there are, either you or I have made a mistake. | |
| Unlike patches for the 3.x kernels, patches for the 3.x.y kernels | |
| (also known as the -stable kernels) are not incremental but instead apply | |
| directly to the base 3.x kernel. For example, if your base kernel is 3.0 | |
| and you want to apply the 3.0.3 patch, you must not first apply the 3.0.1 | |
| and 3.0.2 patches. Similarly, if you are running kernel version 3.0.2 and | |
| want to jump to 3.0.3, you must first reverse the 3.0.2 patch (that is, | |
| patch -R) _before_ applying the 3.0.3 patch. You can read more on this in | |
| Documentation/applying-patches.txt | |
| Alternatively, the script patch-kernel can be used to automate this | |
| process. It determines the current kernel version and applies any | |
| patches found. | |
| linux/scripts/patch-kernel linux | |
| The first argument in the command above is the location of the | |
| kernel source. Patches are applied from the current directory, but | |
| an alternative directory can be specified as the second argument. | |
| - Make sure you have no stale .o files and dependencies lying around: | |
| cd linux | |
| make mrproper | |
| You should now have the sources correctly installed. | |
| SOFTWARE REQUIREMENTS | |
| Compiling and running the 3.x kernels requires up-to-date | |
| versions of various software packages. Consult | |
| Documentation/Changes for the minimum version numbers required | |
| and how to get updates for these packages. Beware that using | |
| excessively old versions of these packages can cause indirect | |
| errors that are very difficult to track down, so don't assume that | |
| you can just update packages when obvious problems arise during | |
| build or operation. | |
| BUILD directory for the kernel: | |
| When compiling the kernel, all output files will per default be | |
| stored together with the kernel source code. | |
| Using the option "make O=output/dir" allow you to specify an alternate | |
| place for the output files (including .config). | |
| Example: | |
| kernel source code: /usr/src/linux-3.X | |
| build directory: /home/name/build/kernel | |
| To configure and build the kernel, use: | |
| cd /usr/src/linux-3.X | |
| make O=/home/name/build/kernel menuconfig | |
| make O=/home/name/build/kernel | |
| sudo make O=/home/name/build/kernel modules_install install | |
| Please note: If the 'O=output/dir' option is used, then it must be | |
| used for all invocations of make. | |
| CONFIGURING the kernel: | |
| Do not skip this step even if you are only upgrading one minor | |
| version. New configuration options are added in each release, and | |
| odd problems will turn up if the configuration files are not set up | |
| as expected. If you want to carry your existing configuration to a | |
| new version with minimal work, use "make oldconfig", which will | |
| only ask you for the answers to new questions. | |
| - Alternative configuration commands are: | |
| "make config" Plain text interface. | |
| "make menuconfig" Text based color menus, radiolists & dialogs. | |
| "make nconfig" Enhanced text based color menus. | |
| "make xconfig" X windows (Qt) based configuration tool. | |
| "make gconfig" X windows (Gtk) based configuration tool. | |
| "make oldconfig" Default all questions based on the contents of | |
| your existing ./.config file and asking about | |
| new config symbols. | |
| "make silentoldconfig" | |
| Like above, but avoids cluttering the screen | |
| with questions already answered. | |
| Additionally updates the dependencies. | |
| "make olddefconfig" | |
| Like above, but sets new symbols to their default | |
| values without prompting. | |
| "make defconfig" Create a ./.config file by using the default | |
| symbol values from either arch/$ARCH/defconfig | |
| or arch/$ARCH/configs/${PLATFORM}_defconfig, | |
| depending on the architecture. | |
| "make ${PLATFORM}_defconfig" | |
| Create a ./.config file by using the default | |
| symbol values from | |
| arch/$ARCH/configs/${PLATFORM}_defconfig. | |
| Use "make help" to get a list of all available | |
| platforms of your architecture. | |
| "make allyesconfig" | |
| Create a ./.config file by setting symbol | |
| values to 'y' as much as possible. | |
| "make allmodconfig" | |
| Create a ./.config file by setting symbol | |
| values to 'm' as much as possible. | |
| "make allnoconfig" Create a ./.config file by setting symbol | |
| values to 'n' as much as possible. | |
| "make randconfig" Create a ./.config file by setting symbol | |
| values to random values. | |
| "make localmodconfig" Create a config based on current config and | |
| loaded modules (lsmod). Disables any module | |
| option that is not needed for the loaded modules. | |
| To create a localmodconfig for another machine, | |
| store the lsmod of that machine into a file | |
| and pass it in as a LSMOD parameter. | |
| target$ lsmod > /tmp/mylsmod | |
| target$ scp /tmp/mylsmod host:/tmp | |
| host$ make LSMOD=/tmp/mylsmod localmodconfig | |
| The above also works when cross compiling. | |
| "make localyesconfig" Similar to localmodconfig, except it will convert | |
| all module options to built in (=y) options. | |
| You can find more information on using the Linux kernel config tools | |
| in Documentation/kbuild/kconfig.txt. | |
| - NOTES on "make config": | |
| - Having unnecessary drivers will make the kernel bigger, and can | |
| under some circumstances lead to problems: probing for a | |
| nonexistent controller card may confuse your other controllers | |
| - Compiling the kernel with "Processor type" set higher than 386 | |
| will result in a kernel that does NOT work on a 386. The | |
| kernel will detect this on bootup, and give up. | |
| - A kernel with math-emulation compiled in will still use the | |
| coprocessor if one is present: the math emulation will just | |
| never get used in that case. The kernel will be slightly larger, | |
| but will work on different machines regardless of whether they | |
| have a math coprocessor or not. | |
| - The "kernel hacking" configuration details usually result in a | |
| bigger or slower kernel (or both), and can even make the kernel | |
| less stable by configuring some routines to actively try to | |
| break bad code to find kernel problems (kmalloc()). Thus you | |
| should probably answer 'n' to the questions for "development", | |
| "experimental", or "debugging" features. | |
| COMPILING the kernel: | |
| - Make sure you have at least gcc 3.2 available. | |
| For more information, refer to Documentation/Changes. | |
| Please note that you can still run a.out user programs with this kernel. | |
| - Do a "make" to create a compressed kernel image. It is also | |
| possible to do "make install" if you have lilo installed to suit the | |
| kernel makefiles, but you may want to check your particular lilo setup first. | |
| To do the actual install, you have to be root, but none of the normal | |
| build should require that. Don't take the name of root in vain. | |
| - If you configured any of the parts of the kernel as `modules', you | |
| will also have to do "make modules_install". | |
| - Verbose kernel compile/build output: | |
| Normally, the kernel build system runs in a fairly quiet mode (but not | |
| totally silent). However, sometimes you or other kernel developers need | |
| to see compile, link, or other commands exactly as they are executed. | |
| For this, use "verbose" build mode. This is done by inserting | |
| "V=1" in the "make" command. E.g.: | |
| make V=1 all | |
| To have the build system also tell the reason for the rebuild of each | |
| target, use "V=2". The default is "V=0". | |
| - Keep a backup kernel handy in case something goes wrong. This is | |
| especially true for the development releases, since each new release | |
| contains new code which has not been debugged. Make sure you keep a | |
| backup of the modules corresponding to that kernel, as well. If you | |
| are installing a new kernel with the same version number as your | |
| working kernel, make a backup of your modules directory before you | |
| do a "make modules_install". | |
| Alternatively, before compiling, use the kernel config option | |
| "LOCALVERSION" to append a unique suffix to the regular kernel version. | |
| LOCALVERSION can be set in the "General Setup" menu. | |
| - In order to boot your new kernel, you'll need to copy the kernel | |
| image (e.g. .../linux/arch/i386/boot/bzImage after compilation) | |
| to the place where your regular bootable kernel is found. | |
| - Booting a kernel directly from a floppy without the assistance of a | |
| bootloader such as LILO, is no longer supported. | |
| If you boot Linux from the hard drive, chances are you use LILO, which | |
| uses the kernel image as specified in the file /etc/lilo.conf. The | |
| kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or | |
| /boot/bzImage. To use the new kernel, save a copy of the old image | |
| and copy the new image over the old one. Then, you MUST RERUN LILO | |
| to update the loading map!! If you don't, you won't be able to boot | |
| the new kernel image. | |
| Reinstalling LILO is usually a matter of running /sbin/lilo. | |
| You may wish to edit /etc/lilo.conf to specify an entry for your | |
| old kernel image (say, /vmlinux.old) in case the new one does not | |
| work. See the LILO docs for more information. | |
| After reinstalling LILO, you should be all set. Shutdown the system, | |
| reboot, and enjoy! | |
| If you ever need to change the default root device, video mode, | |
| ramdisk size, etc. in the kernel image, use the 'rdev' program (or | |
| alternatively the LILO boot options when appropriate). No need to | |
| recompile the kernel to change these parameters. | |
| - Reboot with the new kernel and enjoy. | |
| IF SOMETHING GOES WRONG: | |
| - If you have problems that seem to be due to kernel bugs, please check | |
| the file MAINTAINERS to see if there is a particular person associated | |
| with the part of the kernel that you are having trouble with. If there | |
| isn't anyone listed there, then the second best thing is to mail | |
| them to me (torvalds@linux-foundation.org), and possibly to any other | |
| relevant mailing-list or to the newsgroup. | |
| - In all bug-reports, *please* tell what kernel you are talking about, | |
| how to duplicate the problem, and what your setup is (use your common | |
| sense). If the problem is new, tell me so, and if the problem is | |
| old, please try to tell me when you first noticed it. | |
| - If the bug results in a message like | |
| unable to handle kernel paging request at address C0000010 | |
| Oops: 0002 | |
| EIP: 0010:XXXXXXXX | |
| eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx | |
| esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx | |
| ds: xxxx es: xxxx fs: xxxx gs: xxxx | |
| Pid: xx, process nr: xx | |
| xx xx xx xx xx xx xx xx xx xx | |
| or similar kernel debugging information on your screen or in your | |
| system log, please duplicate it *exactly*. The dump may look | |
| incomprehensible to you, but it does contain information that may | |
| help debugging the problem. The text above the dump is also | |
| important: it tells something about why the kernel dumped code (in | |
| the above example, it's due to a bad kernel pointer). More information | |
| on making sense of the dump is in Documentation/oops-tracing.txt | |
| - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump | |
| as is, otherwise you will have to use the "ksymoops" program to make | |
| sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred). | |
| This utility can be downloaded from | |
| ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ . | |
| Alternatively, you can do the dump lookup by hand: | |
| - In debugging dumps like the above, it helps enormously if you can | |
| look up what the EIP value means. The hex value as such doesn't help | |
| me or anybody else very much: it will depend on your particular | |
| kernel setup. What you should do is take the hex value from the EIP | |
| line (ignore the "0010:"), and look it up in the kernel namelist to | |
| see which kernel function contains the offending address. | |
| To find out the kernel function name, you'll need to find the system | |
| binary associated with the kernel that exhibited the symptom. This is | |
| the file 'linux/vmlinux'. To extract the namelist and match it against | |
| the EIP from the kernel crash, do: | |
| nm vmlinux | sort | less | |
| This will give you a list of kernel addresses sorted in ascending | |
| order, from which it is simple to find the function that contains the | |
| offending address. Note that the address given by the kernel | |
| debugging messages will not necessarily match exactly with the | |
| function addresses (in fact, that is very unlikely), so you can't | |
| just 'grep' the list: the list will, however, give you the starting | |
| point of each kernel function, so by looking for the function that | |
| has a starting address lower than the one you are searching for but | |
| is followed by a function with a higher address you will find the one | |
| you want. In fact, it may be a good idea to include a bit of | |
| "context" in your problem report, giving a few lines around the | |
| interesting one. | |
| If you for some reason cannot do the above (you have a pre-compiled | |
| kernel image or similar), telling me as much about your setup as | |
| possible will help. Please read the REPORTING-BUGS document for details. | |
| - Alternatively, you can use gdb on a running kernel. (read-only; i.e. you | |
| cannot change values or set break points.) To do this, first compile the | |
| kernel with -g; edit arch/i386/Makefile appropriately, then do a "make | |
| clean". You'll also need to enable CONFIG_PROC_FS (via "make config"). | |
| After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore". | |
| You can now use all the usual gdb commands. The command to look up the | |
| point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes | |
| with the EIP value.) | |
| gdb'ing a non-running kernel currently fails because gdb (wrongly) | |
| disregards the starting offset for which the kernel is compiled. | |