1 GNU Linux-libre <http://linux-libre.fsfla.org>
3 These are the release notes for GNU Linux-libre 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.
7 WHAT IS GNU Linux-libre?
9 GNU Linux-libre is a Free version of the kernel Linux (see below),
10 suitable for use with the GNU Operating System in 100% Free
11 GNU/Linux-libre System Distributions.
12 http://www.gnu.org/distros/
14 It removes non-Free components from Linux, that are disguised as
15 source code or distributed in separate files. It also disables
16 run-time requests for non-Free components, shipped separately or as
17 part of Linux, and documentation pointing to them, so as to avoid
18 (Free-)baiting users into the trap of non-Free Software.
19 http://www.fsfla.org/anuncio/2010-11-Linux-2.6.36-libre-debait
21 Linux-libre started within the gNewSense GNU/Linux distribution.
22 It was later adopted by Jeff Moe, who coined its name, and in 2008
23 it became a project maintained by FSF Latin America. In 2012, it
24 became part of the GNU Project.
26 The GNU Linux-libre project takes a minimal-changes approach to
27 cleaning up Linux, making no effort to substitute components that
28 need to be removed with functionally equivalent Free ones.
29 Nevertheless, we encourage and support efforts towards doing so.
30 http://libreplanet.org/wiki/LinuxLibre:Devices_that_require_non-free_firmware
32 Our mascot is Freedo, a light-blue penguin that has just come out
33 of the shower. Although we like penguins, GNU is a much greater
34 contribution to the entire system, so its mascot deserves more
35 promotion. See our web page for their images.
36 http://linux-libre.fsfla.org/
40 Linux is a clone of the Unix kernel, written from scratch by
41 Linus Torvalds with assistance from a loosely-knit team of hackers across
42 the Net. It aims towards POSIX and Single UNIX Specification compliance.
44 It has all the features you would expect in a modern fully-fledged Unix kernel,
45 including true multitasking, virtual memory, shared libraries, demand
46 loading, shared copy-on-write executables, proper memory management,
47 and multistack networking including IPv4 and IPv6.
49 It is distributed under the GNU General Public License - see the
50 accompanying COPYING file for more details.
52 ON WHAT HARDWARE DOES IT RUN?
54 Although originally developed first for 32-bit x86-based PCs (386 or higher),
55 today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and
56 UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell,
57 IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS,
58 Xtensa, Tilera TILE, AVR32 and Renesas M32R architectures.
60 Linux is easily portable to most general-purpose 32- or 64-bit architectures
61 as long as they have a paged memory management unit (PMMU) and a port of the
62 GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has
63 also been ported to a number of architectures without a PMMU, although
64 functionality is then obviously somewhat limited.
65 Linux has also been ported to itself. You can now run the kernel as a
66 userspace application - this is called UserMode Linux (UML).
70 - There is a lot of documentation available both in electronic form on
71 the Internet and in books, both Linux-specific and pertaining to
72 general UNIX questions. I'd recommend looking into the documentation
73 subdirectories on any Linux FTP site for the LDP (Linux Documentation
74 Project) books. This README is not meant to be documentation on the
75 system: there are much better sources available.
77 - There are various README files in the Documentation/ subdirectory:
78 these typically contain kernel-specific installation notes for some
79 drivers for example. See Documentation/00-INDEX for a list of what
80 is contained in each file. Please read the Changes file, as it
81 contains information about the problems, which may result by upgrading
84 - The Documentation/DocBook/ subdirectory contains several guides for
85 kernel developers and users. These guides can be rendered in a
86 number of formats: PostScript (.ps), PDF, HTML, & man-pages, among others.
87 After installation, "make psdocs", "make pdfdocs", "make htmldocs",
88 or "make mandocs" will render the documentation in the requested format.
90 INSTALLING the kernel source:
92 - If you install the full sources, put the kernel tarball in a
93 directory where you have permissions (eg. your home directory) and
96 gzip -cd linux-3.X.tar.gz | tar xvf -
100 bzip2 -dc linux-3.X.tar.bz2 | tar xvf -
102 Replace "X" with the version number of the latest kernel.
104 Do NOT use the /usr/src/linux area! This area has a (usually
105 incomplete) set of kernel headers that are used by the library header
106 files. They should match the library, and not get messed up by
107 whatever the kernel-du-jour happens to be.
109 - You can also upgrade between 3.x releases by patching. Patches are
110 distributed in the traditional gzip and the newer bzip2 format. To
111 install by patching, get all the newer patch files, enter the
112 top level directory of the kernel source (linux-3.X) and execute:
114 gzip -cd ../patch-3.x.gz | patch -p1
118 bzip2 -dc ../patch-3.x.bz2 | patch -p1
120 Replace "x" for all versions bigger than the version "X" of your current
121 source tree, _in_order_, and you should be ok. You may want to remove
122 the backup files (some-file-name~ or some-file-name.orig), and make sure
123 that there are no failed patches (some-file-name# or some-file-name.rej).
124 If there are, either you or I have made a mistake.
126 Unlike patches for the 3.x kernels, patches for the 3.x.y kernels
127 (also known as the -stable kernels) are not incremental but instead apply
128 directly to the base 3.x kernel. For example, if your base kernel is 3.0
129 and you want to apply the 3.0.3 patch, you must not first apply the 3.0.1
130 and 3.0.2 patches. Similarly, if you are running kernel version 3.0.2 and
131 want to jump to 3.0.3, you must first reverse the 3.0.2 patch (that is,
132 patch -R) _before_ applying the 3.0.3 patch. You can read more on this in
133 Documentation/applying-patches.txt
135 Alternatively, the script patch-kernel can be used to automate this
136 process. It determines the current kernel version and applies any
139 linux/scripts/patch-kernel linux
141 The first argument in the command above is the location of the
142 kernel source. Patches are applied from the current directory, but
143 an alternative directory can be specified as the second argument.
145 - Make sure you have no stale .o files and dependencies lying around:
150 You should now have the sources correctly installed.
152 SOFTWARE REQUIREMENTS
154 Compiling and running the 3.x kernels requires up-to-date
155 versions of various software packages. Consult
156 Documentation/Changes for the minimum version numbers required
157 and how to get updates for these packages. Beware that using
158 excessively old versions of these packages can cause indirect
159 errors that are very difficult to track down, so don't assume that
160 you can just update packages when obvious problems arise during
163 BUILD directory for the kernel:
165 When compiling the kernel, all output files will per default be
166 stored together with the kernel source code.
167 Using the option "make O=output/dir" allow you to specify an alternate
168 place for the output files (including .config).
171 kernel source code: /usr/src/linux-3.X
172 build directory: /home/name/build/kernel
174 To configure and build the kernel, use:
176 cd /usr/src/linux-3.X
177 make O=/home/name/build/kernel menuconfig
178 make O=/home/name/build/kernel
179 sudo make O=/home/name/build/kernel modules_install install
181 Please note: If the 'O=output/dir' option is used, then it must be
182 used for all invocations of make.
184 CONFIGURING the kernel:
186 Do not skip this step even if you are only upgrading one minor
187 version. New configuration options are added in each release, and
188 odd problems will turn up if the configuration files are not set up
189 as expected. If you want to carry your existing configuration to a
190 new version with minimal work, use "make oldconfig", which will
191 only ask you for the answers to new questions.
193 - Alternative configuration commands are:
195 "make config" Plain text interface.
197 "make menuconfig" Text based color menus, radiolists & dialogs.
199 "make nconfig" Enhanced text based color menus.
201 "make xconfig" X windows (Qt) based configuration tool.
203 "make gconfig" X windows (Gtk) based configuration tool.
205 "make oldconfig" Default all questions based on the contents of
206 your existing ./.config file and asking about
209 "make silentoldconfig"
210 Like above, but avoids cluttering the screen
211 with questions already answered.
212 Additionally updates the dependencies.
215 Like above, but sets new symbols to their default
216 values without prompting.
218 "make defconfig" Create a ./.config file by using the default
219 symbol values from either arch/$ARCH/defconfig
220 or arch/$ARCH/configs/${PLATFORM}_defconfig,
221 depending on the architecture.
223 "make ${PLATFORM}_defconfig"
224 Create a ./.config file by using the default
226 arch/$ARCH/configs/${PLATFORM}_defconfig.
227 Use "make help" to get a list of all available
228 platforms of your architecture.
231 Create a ./.config file by setting symbol
232 values to 'y' as much as possible.
235 Create a ./.config file by setting symbol
236 values to 'm' as much as possible.
238 "make allnoconfig" Create a ./.config file by setting symbol
239 values to 'n' as much as possible.
241 "make randconfig" Create a ./.config file by setting symbol
242 values to random values.
244 "make localmodconfig" Create a config based on current config and
245 loaded modules (lsmod). Disables any module
246 option that is not needed for the loaded modules.
248 To create a localmodconfig for another machine,
249 store the lsmod of that machine into a file
250 and pass it in as a LSMOD parameter.
252 target$ lsmod > /tmp/mylsmod
253 target$ scp /tmp/mylsmod host:/tmp
255 host$ make LSMOD=/tmp/mylsmod localmodconfig
257 The above also works when cross compiling.
259 "make localyesconfig" Similar to localmodconfig, except it will convert
260 all module options to built in (=y) options.
262 You can find more information on using the Linux kernel config tools
263 in Documentation/kbuild/kconfig.txt.
265 - NOTES on "make config":
267 - Having unnecessary drivers will make the kernel bigger, and can
268 under some circumstances lead to problems: probing for a
269 nonexistent controller card may confuse your other controllers
271 - Compiling the kernel with "Processor type" set higher than 386
272 will result in a kernel that does NOT work on a 386. The
273 kernel will detect this on bootup, and give up.
275 - A kernel with math-emulation compiled in will still use the
276 coprocessor if one is present: the math emulation will just
277 never get used in that case. The kernel will be slightly larger,
278 but will work on different machines regardless of whether they
279 have a math coprocessor or not.
281 - The "kernel hacking" configuration details usually result in a
282 bigger or slower kernel (or both), and can even make the kernel
283 less stable by configuring some routines to actively try to
284 break bad code to find kernel problems (kmalloc()). Thus you
285 should probably answer 'n' to the questions for "development",
286 "experimental", or "debugging" features.
288 COMPILING the kernel:
290 - Make sure you have at least gcc 3.2 available.
291 For more information, refer to Documentation/Changes.
293 Please note that you can still run a.out user programs with this kernel.
295 - Do a "make" to create a compressed kernel image. It is also
296 possible to do "make install" if you have lilo installed to suit the
297 kernel makefiles, but you may want to check your particular lilo setup first.
299 To do the actual install, you have to be root, but none of the normal
300 build should require that. Don't take the name of root in vain.
302 - If you configured any of the parts of the kernel as `modules', you
303 will also have to do "make modules_install".
305 - Verbose kernel compile/build output:
307 Normally, the kernel build system runs in a fairly quiet mode (but not
308 totally silent). However, sometimes you or other kernel developers need
309 to see compile, link, or other commands exactly as they are executed.
310 For this, use "verbose" build mode. This is done by inserting
311 "V=1" in the "make" command. E.g.:
315 To have the build system also tell the reason for the rebuild of each
316 target, use "V=2". The default is "V=0".
318 - Keep a backup kernel handy in case something goes wrong. This is
319 especially true for the development releases, since each new release
320 contains new code which has not been debugged. Make sure you keep a
321 backup of the modules corresponding to that kernel, as well. If you
322 are installing a new kernel with the same version number as your
323 working kernel, make a backup of your modules directory before you
324 do a "make modules_install".
326 Alternatively, before compiling, use the kernel config option
327 "LOCALVERSION" to append a unique suffix to the regular kernel version.
328 LOCALVERSION can be set in the "General Setup" menu.
330 - In order to boot your new kernel, you'll need to copy the kernel
331 image (e.g. .../linux/arch/i386/boot/bzImage after compilation)
332 to the place where your regular bootable kernel is found.
334 - Booting a kernel directly from a floppy without the assistance of a
335 bootloader such as LILO, is no longer supported.
337 If you boot Linux from the hard drive, chances are you use LILO, which
338 uses the kernel image as specified in the file /etc/lilo.conf. The
339 kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
340 /boot/bzImage. To use the new kernel, save a copy of the old image
341 and copy the new image over the old one. Then, you MUST RERUN LILO
342 to update the loading map!! If you don't, you won't be able to boot
343 the new kernel image.
345 Reinstalling LILO is usually a matter of running /sbin/lilo.
346 You may wish to edit /etc/lilo.conf to specify an entry for your
347 old kernel image (say, /vmlinux.old) in case the new one does not
348 work. See the LILO docs for more information.
350 After reinstalling LILO, you should be all set. Shutdown the system,
353 If you ever need to change the default root device, video mode,
354 ramdisk size, etc. in the kernel image, use the 'rdev' program (or
355 alternatively the LILO boot options when appropriate). No need to
356 recompile the kernel to change these parameters.
358 - Reboot with the new kernel and enjoy.
360 IF SOMETHING GOES WRONG:
362 - If you have problems that seem to be due to kernel bugs, please check
363 the file MAINTAINERS to see if there is a particular person associated
364 with the part of the kernel that you are having trouble with. If there
365 isn't anyone listed there, then the second best thing is to mail
366 them to me (torvalds@linux-foundation.org), and possibly to any other
367 relevant mailing-list or to the newsgroup.
369 - In all bug-reports, *please* tell what kernel you are talking about,
370 how to duplicate the problem, and what your setup is (use your common
371 sense). If the problem is new, tell me so, and if the problem is
372 old, please try to tell me when you first noticed it.
374 - If the bug results in a message like
376 unable to handle kernel paging request at address C0000010
379 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
380 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
381 ds: xxxx es: xxxx fs: xxxx gs: xxxx
382 Pid: xx, process nr: xx
383 xx xx xx xx xx xx xx xx xx xx
385 or similar kernel debugging information on your screen or in your
386 system log, please duplicate it *exactly*. The dump may look
387 incomprehensible to you, but it does contain information that may
388 help debugging the problem. The text above the dump is also
389 important: it tells something about why the kernel dumped code (in
390 the above example, it's due to a bad kernel pointer). More information
391 on making sense of the dump is in Documentation/oops-tracing.txt
393 - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump
394 as is, otherwise you will have to use the "ksymoops" program to make
395 sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred).
396 This utility can be downloaded from
397 ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ .
398 Alternatively, you can do the dump lookup by hand:
400 - In debugging dumps like the above, it helps enormously if you can
401 look up what the EIP value means. The hex value as such doesn't help
402 me or anybody else very much: it will depend on your particular
403 kernel setup. What you should do is take the hex value from the EIP
404 line (ignore the "0010:"), and look it up in the kernel namelist to
405 see which kernel function contains the offending address.
407 To find out the kernel function name, you'll need to find the system
408 binary associated with the kernel that exhibited the symptom. This is
409 the file 'linux/vmlinux'. To extract the namelist and match it against
410 the EIP from the kernel crash, do:
412 nm vmlinux | sort | less
414 This will give you a list of kernel addresses sorted in ascending
415 order, from which it is simple to find the function that contains the
416 offending address. Note that the address given by the kernel
417 debugging messages will not necessarily match exactly with the
418 function addresses (in fact, that is very unlikely), so you can't
419 just 'grep' the list: the list will, however, give you the starting
420 point of each kernel function, so by looking for the function that
421 has a starting address lower than the one you are searching for but
422 is followed by a function with a higher address you will find the one
423 you want. In fact, it may be a good idea to include a bit of
424 "context" in your problem report, giving a few lines around the
427 If you for some reason cannot do the above (you have a pre-compiled
428 kernel image or similar), telling me as much about your setup as
429 possible will help. Please read the REPORTING-BUGS document for details.
431 - Alternatively, you can use gdb on a running kernel. (read-only; i.e. you
432 cannot change values or set break points.) To do this, first compile the
433 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
434 clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
436 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
437 You can now use all the usual gdb commands. The command to look up the
438 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
441 gdb'ing a non-running kernel currently fails because gdb (wrongly)
442 disregards the starting offset for which the kernel is compiled.