Folder Documentation/
Folder arch/
Folder block/
Folder crypto/
Folder drivers/
Folder fs/
Folder include/
Folder init/
Folder ipc/
Folder kernel/
Folder lib/
Folder mm/
Folder net/
Folder samples/
Folder scripts/
Folder security/
Folder sound/
Folder usr/
Folder virt/
File COPYING 18693 bytes
File CREDITS 92549 bytes
File Kbuild 1596 bytes
File MAINTAINERS 97351 bytes
File Makefile 54110 bytes
File README 16930 bytes
File REPORTING-BUGS 3172 bytes

  1         Linux kernel release 2.6.xx <>
  3 These are the release notes for Linux version 2.6.  Read them carefully,
  4 as they tell you what this is all about, explain how to install the
  5 kernel, and what to do if something goes wrong. 
  9   Linux is a clone of the operating system Unix, written from scratch by
 10   Linus Torvalds with assistance from a loosely-knit team of hackers across
 11   the Net. It aims towards POSIX and Single UNIX Specification compliance.
 13   It has all the features you would expect in a modern fully-fledged Unix,
 14   including true multitasking, virtual memory, shared libraries, demand
 15   loading, shared copy-on-write executables, proper memory management,
 16   and multistack networking including IPv4 and IPv6.
 18   It is distributed under the GNU General Public License - see the
 19   accompanying COPYING file for more details. 
 23   Although originally developed first for 32-bit x86-based PCs (386 or higher),
 24   today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and
 25   UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell,
 26   IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS,
 27   Xtensa, AVR32 and Renesas M32R architectures.
 29   Linux is easily portable to most general-purpose 32- or 64-bit architectures
 30   as long as they have a paged memory management unit (PMMU) and a port of the
 31   GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has
 32   also been ported to a number of architectures without a PMMU, although
 33   functionality is then obviously somewhat limited.
 34   Linux has also been ported to itself. You can now run the kernel as a
 35   userspace application - this is called UserMode Linux (UML).
 39  - There is a lot of documentation available both in electronic form on
 40    the Internet and in books, both Linux-specific and pertaining to
 41    general UNIX questions.  I'd recommend looking into the documentation
 42    subdirectories on any Linux FTP site for the LDP (Linux Documentation
 43    Project) books.  This README is not meant to be documentation on the
 44    system: there are much better sources available.
 46  - There are various README files in the Documentation/ subdirectory:
 47    these typically contain kernel-specific installation notes for some 
 48    drivers for example. See Documentation/00-INDEX for a list of what
 49    is contained in each file.  Please read the Changes file, as it
 50    contains information about the problems, which may result by upgrading
 51    your kernel.
 53  - The Documentation/DocBook/ subdirectory contains several guides for
 54    kernel developers and users.  These guides can be rendered in a
 55    number of formats:  PostScript (.ps), PDF, and HTML, among others.
 56    After installation, "make psdocs", "make pdfdocs", or "make htmldocs"
 57    will render the documentation in the requested format.
 59 INSTALLING the kernel:
 61  - If you install the full sources, put the kernel tarball in a
 62    directory where you have permissions (eg. your home directory) and
 63    unpack it:
 65                 gzip -cd linux-2.6.XX.tar.gz | tar xvf -
 67    or
 68                 bzip2 -dc linux-2.6.XX.tar.bz2 | tar xvf -
 71    Replace "XX" with the version number of the latest kernel.
 73    Do NOT use the /usr/src/linux area! This area has a (usually
 74    incomplete) set of kernel headers that are used by the library header
 75    files.  They should match the library, and not get messed up by
 76    whatever the kernel-du-jour happens to be.
 78  - You can also upgrade between 2.6.xx releases by patching.  Patches are
 79    distributed in the traditional gzip and the newer bzip2 format.  To
 80    install by patching, get all the newer patch files, enter the
 81    top level directory of the kernel source (linux-2.6.xx) and execute:
 83                 gzip -cd ../patch-2.6.xx.gz | patch -p1
 85    or
 86                 bzip2 -dc ../patch-2.6.xx.bz2 | patch -p1
 88    (repeat xx for all versions bigger than the version of your current
 89    source tree, _in_order_) and you should be ok.  You may want to remove
 90    the backup files (xxx~ or xxx.orig), and make sure that there are no
 91    failed patches (xxx# or xxx.rej). If there are, either you or me has
 92    made a mistake.
 94    Unlike patches for the 2.6.x kernels, patches for the 2.6.x.y kernels
 95    (also known as the -stable kernels) are not incremental but instead apply
 96    directly to the base 2.6.x kernel.  Please read
 97    Documentation/applying-patches.txt for more information.
 99    Alternatively, the script patch-kernel can be used to automate this
100    process.  It determines the current kernel version and applies any
101    patches found.
103                 linux/scripts/patch-kernel linux
105    The first argument in the command above is the location of the
106    kernel source.  Patches are applied from the current directory, but
107    an alternative directory can be specified as the second argument.
109  - If you are upgrading between releases using the stable series patches
110    (for example, patch-2.6.xx.y), note that these "dot-releases" are
111    not incremental and must be applied to the 2.6.xx base tree. For
112    example, if your base kernel is 2.6.12 and you want to apply the
113 patch, you do not and indeed must not first apply the
114 and patches. Similarly, if you are running kernel
115    version and want to jump to, you must first
116    reverse the patch (that is, patch -R) _before_ applying
117    the patch.
118    You can read more on this in Documentation/applying-patches.txt
120  - Make sure you have no stale .o files and dependencies lying around:
122                 cd linux
123                 make mrproper
125    You should now have the sources correctly installed.
129    Compiling and running the 2.6.xx kernels requires up-to-date
130    versions of various software packages.  Consult
131    Documentation/Changes for the minimum version numbers required
132    and how to get updates for these packages.  Beware that using
133    excessively old versions of these packages can cause indirect
134    errors that are very difficult to track down, so don't assume that
135    you can just update packages when obvious problems arise during
136    build or operation.
138 BUILD directory for the kernel:
140    When compiling the kernel all output files will per default be
141    stored together with the kernel source code.
142    Using the option "make O=output/dir" allow you to specify an alternate
143    place for the output files (including .config).
144    Example:
145      kernel source code:        /usr/src/linux-2.6.N
146      build directory:           /home/name/build/kernel
148    To configure and build the kernel use:
149    cd /usr/src/linux-2.6.N
150    make O=/home/name/build/kernel menuconfig
151    make O=/home/name/build/kernel
152    sudo make O=/home/name/build/kernel modules_install install
154    Please note: If the 'O=output/dir' option is used then it must be
155    used for all invocations of make.
157 CONFIGURING the kernel:
159    Do not skip this step even if you are only upgrading one minor
160    version.  New configuration options are added in each release, and
161    odd problems will turn up if the configuration files are not set up
162    as expected.  If you want to carry your existing configuration to a
163    new version with minimal work, use "make oldconfig", which will
164    only ask you for the answers to new questions.
166  - Alternate configuration commands are:
167         "make config"      Plain text interface.
168         "make menuconfig"  Text based color menus, radiolists & dialogs.
169         "make xconfig"     X windows (Qt) based configuration tool.
170         "make gconfig"     X windows (Gtk) based configuration tool.
171         "make oldconfig"   Default all questions based on the contents of
172                            your existing ./.config file and asking about
173                            new config symbols.
174         "make silentoldconfig"
175                            Like above, but avoids cluttering the screen
176                            with questions already answered.
177         "make defconfig"   Create a ./.config file by using the default
178                            symbol values from arch/$ARCH/defconfig.
179         "make allyesconfig"
180                            Create a ./.config file by setting symbol
181                            values to 'y' as much as possible.
182         "make allmodconfig"
183                            Create a ./.config file by setting symbol
184                            values to 'm' as much as possible.
185         "make allnoconfig" Create a ./.config file by setting symbol
186                            values to 'n' as much as possible.
187         "make randconfig"  Create a ./.config file by setting symbol
188                            values to random values.
190    The allyesconfig/allmodconfig/allnoconfig/randconfig variants can
191    also use the environment variable KCONFIG_ALLCONFIG to specify a
192    filename that contains config options that the user requires to be
193    set to a specific value.  If KCONFIG_ALLCONFIG=filename is not used,
194    "make *config" checks for a file named "all{yes/mod/no/random}.config"
195    for symbol values that are to be forced.  If this file is not found,
196    it checks for a file named "all.config" to contain forced values.
198         NOTES on "make config":
199         - having unnecessary drivers will make the kernel bigger, and can
200           under some circumstances lead to problems: probing for a
201           nonexistent controller card may confuse your other controllers
202         - compiling the kernel with "Processor type" set higher than 386
203           will result in a kernel that does NOT work on a 386.  The
204           kernel will detect this on bootup, and give up.
205         - A kernel with math-emulation compiled in will still use the
206           coprocessor if one is present: the math emulation will just
207           never get used in that case.  The kernel will be slightly larger,
208           but will work on different machines regardless of whether they
209           have a math coprocessor or not. 
210         - the "kernel hacking" configuration details usually result in a
211           bigger or slower kernel (or both), and can even make the kernel
212           less stable by configuring some routines to actively try to
213           break bad code to find kernel problems (kmalloc()).  Thus you
214           should probably answer 'n' to the questions for
215           "development", "experimental", or "debugging" features.
217 COMPILING the kernel:
219  - Make sure you have at least gcc 3.2 available.
220    For more information, refer to Documentation/Changes.
222    Please note that you can still run a.out user programs with this kernel.
224  - Do a "make" to create a compressed kernel image. It is also
225    possible to do "make install" if you have lilo installed to suit the
226    kernel makefiles, but you may want to check your particular lilo setup first.
228    To do the actual install you have to be root, but none of the normal
229    build should require that. Don't take the name of root in vain.
231  - If you configured any of the parts of the kernel as `modules', you
232    will also have to do "make modules_install".
234  - Keep a backup kernel handy in case something goes wrong.  This is 
235    especially true for the development releases, since each new release
236    contains new code which has not been debugged.  Make sure you keep a
237    backup of the modules corresponding to that kernel, as well.  If you
238    are installing a new kernel with the same version number as your
239    working kernel, make a backup of your modules directory before you
240    do a "make modules_install".
241    Alternatively, before compiling, use the kernel config option
242    "LOCALVERSION" to append a unique suffix to the regular kernel version.
243    LOCALVERSION can be set in the "General Setup" menu.
245  - In order to boot your new kernel, you'll need to copy the kernel
246    image (e.g. .../linux/arch/i386/boot/bzImage after compilation)
247    to the place where your regular bootable kernel is found. 
249  - Booting a kernel directly from a floppy without the assistance of a
250    bootloader such as LILO, is no longer supported.
252    If you boot Linux from the hard drive, chances are you use LILO which
253    uses the kernel image as specified in the file /etc/lilo.conf.  The
254    kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
255    /boot/bzImage.  To use the new kernel, save a copy of the old image
256    and copy the new image over the old one.  Then, you MUST RERUN LILO
257    to update the loading map!! If you don't, you won't be able to boot
258    the new kernel image.
260    Reinstalling LILO is usually a matter of running /sbin/lilo. 
261    You may wish to edit /etc/lilo.conf to specify an entry for your
262    old kernel image (say, /vmlinux.old) in case the new one does not
263    work.  See the LILO docs for more information. 
265    After reinstalling LILO, you should be all set.  Shutdown the system,
266    reboot, and enjoy!
268    If you ever need to change the default root device, video mode,
269    ramdisk size, etc.  in the kernel image, use the 'rdev' program (or
270    alternatively the LILO boot options when appropriate).  No need to
271    recompile the kernel to change these parameters. 
273  - Reboot with the new kernel and enjoy. 
277  - If you have problems that seem to be due to kernel bugs, please check
278    the file MAINTAINERS to see if there is a particular person associated
279    with the part of the kernel that you are having trouble with. If there
280    isn't anyone listed there, then the second best thing is to mail
281    them to me (, and possibly to any other
282    relevant mailing-list or to the newsgroup.
284  - In all bug-reports, *please* tell what kernel you are talking about,
285    how to duplicate the problem, and what your setup is (use your common
286    sense).  If the problem is new, tell me so, and if the problem is
287    old, please try to tell me when you first noticed it.
289  - If the bug results in a message like
291         unable to handle kernel paging request at address C0000010
292         Oops: 0002
293         EIP:   0010:XXXXXXXX
294         eax: xxxxxxxx   ebx: xxxxxxxx   ecx: xxxxxxxx   edx: xxxxxxxx
295         esi: xxxxxxxx   edi: xxxxxxxx   ebp: xxxxxxxx
296         ds: xxxx  es: xxxx  fs: xxxx  gs: xxxx
297         Pid: xx, process nr: xx
298         xx xx xx xx xx xx xx xx xx xx
300    or similar kernel debugging information on your screen or in your
301    system log, please duplicate it *exactly*.  The dump may look
302    incomprehensible to you, but it does contain information that may
303    help debugging the problem.  The text above the dump is also
304    important: it tells something about why the kernel dumped code (in
305    the above example it's due to a bad kernel pointer). More information
306    on making sense of the dump is in Documentation/oops-tracing.txt
308  - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump
309    as is, otherwise you will have to use the "ksymoops" program to make
310    sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred).
311    This utility can be downloaded from
312    ftp://ftp.<country> .
313    Alternately you can do the dump lookup by hand:
315  - In debugging dumps like the above, it helps enormously if you can
316    look up what the EIP value means.  The hex value as such doesn't help
317    me or anybody else very much: it will depend on your particular
318    kernel setup.  What you should do is take the hex value from the EIP
319    line (ignore the "0010:"), and look it up in the kernel namelist to
320    see which kernel function contains the offending address.
322    To find out the kernel function name, you'll need to find the system
323    binary associated with the kernel that exhibited the symptom.  This is
324    the file 'linux/vmlinux'.  To extract the namelist and match it against
325    the EIP from the kernel crash, do:
327                 nm vmlinux | sort | less
329    This will give you a list of kernel addresses sorted in ascending
330    order, from which it is simple to find the function that contains the
331    offending address.  Note that the address given by the kernel
332    debugging messages will not necessarily match exactly with the
333    function addresses (in fact, that is very unlikely), so you can't
334    just 'grep' the list: the list will, however, give you the starting
335    point of each kernel function, so by looking for the function that
336    has a starting address lower than the one you are searching for but
337    is followed by a function with a higher address you will find the one
338    you want.  In fact, it may be a good idea to include a bit of
339    "context" in your problem report, giving a few lines around the
340    interesting one. 
342    If you for some reason cannot do the above (you have a pre-compiled
343    kernel image or similar), telling me as much about your setup as
344    possible will help.  Please read the REPORTING-BUGS document for details.
346  - Alternately, you can use gdb on a running kernel. (read-only; i.e. you
347    cannot change values or set break points.) To do this, first compile the
348    kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
349    clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
351    After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
352    You can now use all the usual gdb commands. The command to look up the
353    point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
354    with the EIP value.)
356    gdb'ing a non-running kernel currently fails because gdb (wrongly)
357    disregards the starting offset for which the kernel is compiled.

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