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Linux/

Folder Documentation/
Folder arch/
Folder block/
Folder crypto/
Folder drivers/
Folder firmware/
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 tools/
Folder usr/
Folder virt/
File COPYING 18693 bytes
File CREDITS 95851 bytes
File Kbuild 2536 bytes
File Kconfig 252 bytes
File MAINTAINERS 278581 bytes
File Makefile 51741 bytes
File README 18736 bytes
File REPORTING-BUGS 7485 bytes

  1         Linux kernel release 3.x <http://kernel.org/>
  2 
  3 These are the release notes for Linux version 3.  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. 
  6 
  7 WHAT IS LINUX?
  8 
  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.
 12 
 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.
 17 
 18   It is distributed under the GNU General Public License - see the
 19   accompanying COPYING file for more details. 
 20 
 21 ON WHAT HARDWARE DOES IT RUN?
 22 
 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, Tilera TILE, AVR32 and Renesas M32R architectures.
 28 
 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).
 36 
 37 DOCUMENTATION:
 38 
 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.
 45 
 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.
 52 
 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, HTML, & man-pages, among others.
 56    After installation, "make psdocs", "make pdfdocs", "make htmldocs",
 57    or "make mandocs" will render the documentation in the requested format.
 58 
 59 INSTALLING the kernel source:
 60 
 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:
 64 
 65      gzip -cd linux-3.X.tar.gz | tar xvf -
 66 
 67    or
 68 
 69      bzip2 -dc linux-3.X.tar.bz2 | tar xvf -
 70 
 71    Replace "X" with the version number of the latest kernel.
 72 
 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.
 77 
 78  - You can also upgrade between 3.x 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-3.X) and execute:
 82 
 83      gzip -cd ../patch-3.x.gz | patch -p1
 84 
 85    or
 86 
 87      bzip2 -dc ../patch-3.x.bz2 | patch -p1
 88 
 89    Replace "x" for all versions bigger than the version "X" of your current
 90    source tree, _in_order_, and you should be ok.  You may want to remove
 91    the backup files (some-file-name~ or some-file-name.orig), and make sure
 92    that there are no failed patches (some-file-name# or some-file-name.rej).
 93    If there are, either you or I have made a mistake.
 94 
 95    Unlike patches for the 3.x kernels, patches for the 3.x.y kernels
 96    (also known as the -stable kernels) are not incremental but instead apply
 97    directly to the base 3.x kernel.  For example, if your base kernel is 3.0
 98    and you want to apply the 3.0.3 patch, you must not first apply the 3.0.1
 99    and 3.0.2 patches. Similarly, if you are running kernel version 3.0.2 and
100    want to jump to 3.0.3, you must first reverse the 3.0.2 patch (that is,
101    patch -R) _before_ applying the 3.0.3 patch. You can read more on this in
102    Documentation/applying-patches.txt
103 
104    Alternatively, the script patch-kernel can be used to automate this
105    process.  It determines the current kernel version and applies any
106    patches found.
107 
108      linux/scripts/patch-kernel linux
109 
110    The first argument in the command above is the location of the
111    kernel source.  Patches are applied from the current directory, but
112    an alternative directory can be specified as the second argument.
113 
114  - Make sure you have no stale .o files and dependencies lying around:
115 
116      cd linux
117      make mrproper
118 
119    You should now have the sources correctly installed.
120 
121 SOFTWARE REQUIREMENTS
122 
123    Compiling and running the 3.x kernels requires up-to-date
124    versions of various software packages.  Consult
125    Documentation/Changes for the minimum version numbers required
126    and how to get updates for these packages.  Beware that using
127    excessively old versions of these packages can cause indirect
128    errors that are very difficult to track down, so don't assume that
129    you can just update packages when obvious problems arise during
130    build or operation.
131 
132 BUILD directory for the kernel:
133 
134    When compiling the kernel, all output files will per default be
135    stored together with the kernel source code.
136    Using the option "make O=output/dir" allow you to specify an alternate
137    place for the output files (including .config).
138    Example:
139 
140      kernel source code: /usr/src/linux-3.X
141      build directory:    /home/name/build/kernel
142 
143    To configure and build the kernel, use:
144 
145      cd /usr/src/linux-3.X
146      make O=/home/name/build/kernel menuconfig
147      make O=/home/name/build/kernel
148      sudo make O=/home/name/build/kernel modules_install install
149 
150    Please note: If the 'O=output/dir' option is used, then it must be
151    used for all invocations of make.
152 
153 CONFIGURING the kernel:
154 
155    Do not skip this step even if you are only upgrading one minor
156    version.  New configuration options are added in each release, and
157    odd problems will turn up if the configuration files are not set up
158    as expected.  If you want to carry your existing configuration to a
159    new version with minimal work, use "make oldconfig", which will
160    only ask you for the answers to new questions.
161 
162  - Alternative configuration commands are:
163 
164      "make config"      Plain text interface.
165 
166      "make menuconfig"  Text based color menus, radiolists & dialogs.
167 
168      "make nconfig"     Enhanced text based color menus.
169 
170      "make xconfig"     X windows (Qt) based configuration tool.
171 
172      "make gconfig"     X windows (Gtk) based configuration tool.
173 
174      "make oldconfig"   Default all questions based on the contents of
175                         your existing ./.config file and asking about
176                         new config symbols.
177 
178      "make silentoldconfig"
179                         Like above, but avoids cluttering the screen
180                         with questions already answered.
181                         Additionally updates the dependencies.
182 
183      "make olddefconfig"
184                         Like above, but sets new symbols to their default
185                         values without prompting.
186 
187      "make defconfig"   Create a ./.config file by using the default
188                         symbol values from either arch/$ARCH/defconfig
189                         or arch/$ARCH/configs/${PLATFORM}_defconfig,
190                         depending on the architecture.
191 
192      "make ${PLATFORM}_defconfig"
193                         Create a ./.config file by using the default
194                         symbol values from
195                         arch/$ARCH/configs/${PLATFORM}_defconfig.
196                         Use "make help" to get a list of all available
197                         platforms of your architecture.
198 
199      "make allyesconfig"
200                         Create a ./.config file by setting symbol
201                         values to 'y' as much as possible.
202 
203      "make allmodconfig"
204                         Create a ./.config file by setting symbol
205                         values to 'm' as much as possible.
206 
207      "make allnoconfig" Create a ./.config file by setting symbol
208                         values to 'n' as much as possible.
209 
210      "make randconfig"  Create a ./.config file by setting symbol
211                         values to random values.
212 
213      "make localmodconfig" Create a config based on current config and
214                            loaded modules (lsmod). Disables any module
215                            option that is not needed for the loaded modules.
216 
217                            To create a localmodconfig for another machine,
218                            store the lsmod of that machine into a file
219                            and pass it in as a LSMOD parameter.
220 
221                    target$ lsmod > /tmp/mylsmod
222                    target$ scp /tmp/mylsmod host:/tmp
223 
224                    host$ make LSMOD=/tmp/mylsmod localmodconfig
225 
226                            The above also works when cross compiling.
227 
228      "make localyesconfig" Similar to localmodconfig, except it will convert
229                            all module options to built in (=y) options.
230 
231    You can find more information on using the Linux kernel config tools
232    in Documentation/kbuild/kconfig.txt.
233 
234  - NOTES on "make config":
235 
236     - Having unnecessary drivers will make the kernel bigger, and can
237       under some circumstances lead to problems: probing for a
238       nonexistent controller card may confuse your other controllers
239 
240     - Compiling the kernel with "Processor type" set higher than 386
241       will result in a kernel that does NOT work on a 386.  The
242       kernel will detect this on bootup, and give up.
243 
244     - A kernel with math-emulation compiled in will still use the
245       coprocessor if one is present: the math emulation will just
246       never get used in that case.  The kernel will be slightly larger,
247       but will work on different machines regardless of whether they
248       have a math coprocessor or not.
249 
250     - The "kernel hacking" configuration details usually result in a
251       bigger or slower kernel (or both), and can even make the kernel
252       less stable by configuring some routines to actively try to
253       break bad code to find kernel problems (kmalloc()).  Thus you
254       should probably answer 'n' to the questions for "development",
255       "experimental", or "debugging" features.
256 
257 COMPILING the kernel:
258 
259  - Make sure you have at least gcc 3.2 available.
260    For more information, refer to Documentation/Changes.
261 
262    Please note that you can still run a.out user programs with this kernel.
263 
264  - Do a "make" to create a compressed kernel image. It is also
265    possible to do "make install" if you have lilo installed to suit the
266    kernel makefiles, but you may want to check your particular lilo setup first.
267 
268    To do the actual install, you have to be root, but none of the normal
269    build should require that. Don't take the name of root in vain.
270 
271  - If you configured any of the parts of the kernel as `modules', you
272    will also have to do "make modules_install".
273 
274  - Verbose kernel compile/build output:
275 
276    Normally, the kernel build system runs in a fairly quiet mode (but not
277    totally silent).  However, sometimes you or other kernel developers need
278    to see compile, link, or other commands exactly as they are executed.
279    For this, use "verbose" build mode.  This is done by inserting
280    "V=1" in the "make" command.  E.g.:
281 
282      make V=1 all
283 
284    To have the build system also tell the reason for the rebuild of each
285    target, use "V=2".  The default is "V=0".
286 
287  - Keep a backup kernel handy in case something goes wrong.  This is 
288    especially true for the development releases, since each new release
289    contains new code which has not been debugged.  Make sure you keep a
290    backup of the modules corresponding to that kernel, as well.  If you
291    are installing a new kernel with the same version number as your
292    working kernel, make a backup of your modules directory before you
293    do a "make modules_install".
294 
295    Alternatively, before compiling, use the kernel config option
296    "LOCALVERSION" to append a unique suffix to the regular kernel version.
297    LOCALVERSION can be set in the "General Setup" menu.
298 
299  - In order to boot your new kernel, you'll need to copy the kernel
300    image (e.g. .../linux/arch/i386/boot/bzImage after compilation)
301    to the place where your regular bootable kernel is found. 
302 
303  - Booting a kernel directly from a floppy without the assistance of a
304    bootloader such as LILO, is no longer supported.
305 
306    If you boot Linux from the hard drive, chances are you use LILO, which
307    uses the kernel image as specified in the file /etc/lilo.conf.  The
308    kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
309    /boot/bzImage.  To use the new kernel, save a copy of the old image
310    and copy the new image over the old one.  Then, you MUST RERUN LILO
311    to update the loading map!! If you don't, you won't be able to boot
312    the new kernel image.
313 
314    Reinstalling LILO is usually a matter of running /sbin/lilo. 
315    You may wish to edit /etc/lilo.conf to specify an entry for your
316    old kernel image (say, /vmlinux.old) in case the new one does not
317    work.  See the LILO docs for more information. 
318 
319    After reinstalling LILO, you should be all set.  Shutdown the system,
320    reboot, and enjoy!
321 
322    If you ever need to change the default root device, video mode,
323    ramdisk size, etc.  in the kernel image, use the 'rdev' program (or
324    alternatively the LILO boot options when appropriate).  No need to
325    recompile the kernel to change these parameters. 
326 
327  - Reboot with the new kernel and enjoy. 
328 
329 IF SOMETHING GOES WRONG:
330 
331  - If you have problems that seem to be due to kernel bugs, please check
332    the file MAINTAINERS to see if there is a particular person associated
333    with the part of the kernel that you are having trouble with. If there
334    isn't anyone listed there, then the second best thing is to mail
335    them to me (torvalds@linux-foundation.org), and possibly to any other
336    relevant mailing-list or to the newsgroup.
337 
338  - In all bug-reports, *please* tell what kernel you are talking about,
339    how to duplicate the problem, and what your setup is (use your common
340    sense).  If the problem is new, tell me so, and if the problem is
341    old, please try to tell me when you first noticed it.
342 
343  - If the bug results in a message like
344 
345      unable to handle kernel paging request at address C0000010
346      Oops: 0002
347      EIP:   0010:XXXXXXXX
348      eax: xxxxxxxx   ebx: xxxxxxxx   ecx: xxxxxxxx   edx: xxxxxxxx
349      esi: xxxxxxxx   edi: xxxxxxxx   ebp: xxxxxxxx
350      ds: xxxx  es: xxxx  fs: xxxx  gs: xxxx
351      Pid: xx, process nr: xx
352      xx xx xx xx xx xx xx xx xx xx
353 
354    or similar kernel debugging information on your screen or in your
355    system log, please duplicate it *exactly*.  The dump may look
356    incomprehensible to you, but it does contain information that may
357    help debugging the problem.  The text above the dump is also
358    important: it tells something about why the kernel dumped code (in
359    the above example, it's due to a bad kernel pointer). More information
360    on making sense of the dump is in Documentation/oops-tracing.txt
361 
362  - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump
363    as is, otherwise you will have to use the "ksymoops" program to make
364    sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred).
365    This utility can be downloaded from
366    ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ .
367    Alternatively, you can do the dump lookup by hand:
368 
369  - In debugging dumps like the above, it helps enormously if you can
370    look up what the EIP value means.  The hex value as such doesn't help
371    me or anybody else very much: it will depend on your particular
372    kernel setup.  What you should do is take the hex value from the EIP
373    line (ignore the "0010:"), and look it up in the kernel namelist to
374    see which kernel function contains the offending address.
375 
376    To find out the kernel function name, you'll need to find the system
377    binary associated with the kernel that exhibited the symptom.  This is
378    the file 'linux/vmlinux'.  To extract the namelist and match it against
379    the EIP from the kernel crash, do:
380 
381      nm vmlinux | sort | less
382 
383    This will give you a list of kernel addresses sorted in ascending
384    order, from which it is simple to find the function that contains the
385    offending address.  Note that the address given by the kernel
386    debugging messages will not necessarily match exactly with the
387    function addresses (in fact, that is very unlikely), so you can't
388    just 'grep' the list: the list will, however, give you the starting
389    point of each kernel function, so by looking for the function that
390    has a starting address lower than the one you are searching for but
391    is followed by a function with a higher address you will find the one
392    you want.  In fact, it may be a good idea to include a bit of
393    "context" in your problem report, giving a few lines around the
394    interesting one. 
395 
396    If you for some reason cannot do the above (you have a pre-compiled
397    kernel image or similar), telling me as much about your setup as
398    possible will help.  Please read the REPORTING-BUGS document for details.
399 
400  - Alternatively, you can use gdb on a running kernel. (read-only; i.e. you
401    cannot change values or set break points.) To do this, first compile the
402    kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
403    clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
404 
405    After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
406    You can now use all the usual gdb commands. The command to look up the
407    point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
408    with the EIP value.)
409 
410    gdb'ing a non-running kernel currently fails because gdb (wrongly)
411    disregards the starting offset for which the kernel is compiled.
412 

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