Linux kernel release 2.6.xx <http://kernel.org/>  These are the release notes for Linux version 2.6.  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, 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-2.6.XX.tar.gz | tar xvf -     or 		bzip2 -dc linux-2.6.XX.tar.bz2 | tar xvf -      Replace "XX" 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 2.6.xx 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-2.6.xx) and execute:  		gzip -cd ../patch-2.6.xx.gz | patch -p1     or 		bzip2 -dc ../patch-2.6.xx.bz2 | patch -p1     (repeat xx for all versions bigger than the version of your current    source tree, _in_order_) and you should be ok.  You may want to remove    the backup files (xxx~ or xxx.orig), and make sure that there are no    failed patches (xxx# or xxx.rej). If there are, either you or me has    made a mistake.     Unlike patches for the 2.6.x kernels, patches for the 2.6.x.y kernels    (also known as the -stable kernels) are not incremental but instead apply    directly to the base 2.6.x kernel.  Please read    Documentation/applying-patches.txt for more information.     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.   - If you are upgrading between releases using the stable series patches    (for example, patch-2.6.xx.y), note that these "dot-releases" are    not incremental and must be applied to the 2.6.xx base tree. For    example, if your base kernel is 2.6.12 and you want to apply the    2.6.12.3 patch, you do not and indeed must not first apply the    2.6.12.1 and 2.6.12.2 patches. Similarly, if you are running kernel    version 2.6.12.2 and want to jump to 2.6.12.3, you must first    reverse the 2.6.12.2 patch (that is, patch -R) _before_ applying    the 2.6.12.3 patch.    You can read more on this in Documentation/applying-patches.txt   - 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 2.6.xx 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-2.6.N      build directory:		/home/name/build/kernel     To configure and build the kernel use:    cd /usr/src/linux-2.6.N    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.   - Alternate configuration commands are: 	"make config"      Plain text interface. 	"make menuconfig"  Text based color menus, radiolists & dialogs. 	"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 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.     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/ .    Alternately 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.   - Alternately, 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.