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/
38 If you are the author of an awesome program and want to join us in
39 writing Free (libre) Software, please consider making it an official
40 GNU program and become a GNU Maintainer. You can find instructions
41 on how to do so at https://www.gnu.org/help/evaluation. We look
42 forward to hacking with you! :)
46 Linux is a clone of the Unix kernel, written from scratch by
47 Linus Torvalds with assistance from a loosely-knit team of hackers across
48 the Net. It aims towards POSIX and Single UNIX Specification compliance.
50 It has all the features you would expect in a modern fully-fledged Unix kernel,
51 including true multitasking, virtual memory, shared libraries, demand
52 loading, shared copy-on-write executables, proper memory management,
53 and multistack networking including IPv4 and IPv6.
55 It is distributed under the GNU General Public License - see the
56 accompanying COPYING file for more details.
58 ON WHAT HARDWARE DOES IT RUN?
60 Although originally developed first for 32-bit x86-based PCs (386 or higher),
61 today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and
62 UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell,
63 IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS,
64 Xtensa, Tilera TILE, AVR32, ARC and Renesas M32R architectures.
66 Linux is easily portable to most general-purpose 32- or 64-bit architectures
67 as long as they have a paged memory management unit (PMMU) and a port of the
68 GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has
69 also been ported to a number of architectures without a PMMU, although
70 functionality is then obviously somewhat limited.
71 Linux has also been ported to itself. You can now run the kernel as a
72 userspace application - this is called UserMode Linux (UML).
76 - There is a lot of documentation available both in electronic form on
77 the Internet and in books, both Linux-specific and pertaining to
78 general UNIX questions. I'd recommend looking into the documentation
79 subdirectories on any Linux FTP site for the LDP (Linux Documentation
80 Project) books. This README is not meant to be documentation on the
81 system: there are much better sources available.
83 - There are various README files in the Documentation/ subdirectory:
84 these typically contain kernel-specific installation notes for some
85 drivers for example. See Documentation/00-INDEX for a list of what
86 is contained in each file. Please read the Changes file, as it
87 contains information about the problems, which may result by upgrading
90 - The Documentation/DocBook/ subdirectory contains several guides for
91 kernel developers and users. These guides can be rendered in a
92 number of formats: PostScript (.ps), PDF, HTML, & man-pages, among others.
93 After installation, "make psdocs", "make pdfdocs", "make htmldocs",
94 or "make mandocs" will render the documentation in the requested format.
96 INSTALLING the kernel source:
98 - If you install the full sources, put the kernel tarball in a
99 directory where you have permissions (e.g. your home directory) and
102 xz -cd linux-4.X.tar.xz | tar xvf -
104 Replace "X" with the version number of the latest kernel.
106 Do NOT use the /usr/src/linux area! This area has a (usually
107 incomplete) set of kernel headers that are used by the library header
108 files. They should match the library, and not get messed up by
109 whatever the kernel-du-jour happens to be.
111 - You can also upgrade between 4.x releases by patching. Patches are
112 distributed in the xz format. To install by patching, get all the
113 newer patch files, enter the top level directory of the kernel source
114 (linux-4.X) and execute:
116 xz -cd ../patch-4.x.xz | patch -p1
118 Replace "x" for all versions bigger than the version "X" of your current
119 source tree, _in_order_, and you should be ok. You may want to remove
120 the backup files (some-file-name~ or some-file-name.orig), and make sure
121 that there are no failed patches (some-file-name# or some-file-name.rej).
122 If there are, either you or I have made a mistake.
124 Unlike patches for the 4.x kernels, patches for the 4.x.y kernels
125 (also known as the -stable kernels) are not incremental but instead apply
126 directly to the base 4.x kernel. For example, if your base kernel is 4.0
127 and you want to apply the 4.0.3 patch, you must not first apply the 4.0.1
128 and 4.0.2 patches. Similarly, if you are running kernel version 4.0.2 and
129 want to jump to 4.0.3, you must first reverse the 4.0.2 patch (that is,
130 patch -R) _before_ applying the 4.0.3 patch. You can read more on this in
131 Documentation/applying-patches.txt
133 Alternatively, the script patch-kernel can be used to automate this
134 process. It determines the current kernel version and applies any
137 linux/scripts/patch-kernel linux
139 The first argument in the command above is the location of the
140 kernel source. Patches are applied from the current directory, but
141 an alternative directory can be specified as the second argument.
143 - Make sure you have no stale .o files and dependencies lying around:
148 You should now have the sources correctly installed.
150 SOFTWARE REQUIREMENTS
152 Compiling and running the 4.x kernels requires up-to-date
153 versions of various software packages. Consult
154 Documentation/Changes for the minimum version numbers required
155 and how to get updates for these packages. Beware that using
156 excessively old versions of these packages can cause indirect
157 errors that are very difficult to track down, so don't assume that
158 you can just update packages when obvious problems arise during
161 BUILD directory for the kernel:
163 When compiling the kernel, all output files will per default be
164 stored together with the kernel source code.
165 Using the option "make O=output/dir" allows you to specify an alternate
166 place for the output files (including .config).
169 kernel source code: /usr/src/linux-4.X
170 build directory: /home/name/build/kernel
172 To configure and build the kernel, use:
174 cd /usr/src/linux-4.X
175 make O=/home/name/build/kernel menuconfig
176 make O=/home/name/build/kernel
177 sudo make O=/home/name/build/kernel modules_install install
179 Please note: If the 'O=output/dir' option is used, then it must be
180 used for all invocations of make.
182 CONFIGURING the kernel:
184 Do not skip this step even if you are only upgrading one minor
185 version. New configuration options are added in each release, and
186 odd problems will turn up if the configuration files are not set up
187 as expected. If you want to carry your existing configuration to a
188 new version with minimal work, use "make oldconfig", which will
189 only ask you for the answers to new questions.
191 - Alternative configuration commands are:
193 "make config" Plain text interface.
195 "make menuconfig" Text based color menus, radiolists & dialogs.
197 "make nconfig" Enhanced text based color menus.
199 "make xconfig" Qt based configuration tool.
201 "make gconfig" GTK+ based configuration tool.
203 "make oldconfig" Default all questions based on the contents of
204 your existing ./.config file and asking about
207 "make silentoldconfig"
208 Like above, but avoids cluttering the screen
209 with questions already answered.
210 Additionally updates the dependencies.
213 Like above, but sets new symbols to their default
214 values without prompting.
216 "make defconfig" Create a ./.config file by using the default
217 symbol values from either arch/$ARCH/defconfig
218 or arch/$ARCH/configs/${PLATFORM}_defconfig,
219 depending on the architecture.
221 "make ${PLATFORM}_defconfig"
222 Create a ./.config file by using the default
224 arch/$ARCH/configs/${PLATFORM}_defconfig.
225 Use "make help" to get a list of all available
226 platforms of your architecture.
229 Create a ./.config file by setting symbol
230 values to 'y' as much as possible.
233 Create a ./.config file by setting symbol
234 values to 'm' as much as possible.
236 "make allnoconfig" Create a ./.config file by setting symbol
237 values to 'n' as much as possible.
239 "make randconfig" Create a ./.config file by setting symbol
240 values to random values.
242 "make localmodconfig" Create a config based on current config and
243 loaded modules (lsmod). Disables any module
244 option that is not needed for the loaded modules.
246 To create a localmodconfig for another machine,
247 store the lsmod of that machine into a file
248 and pass it in as a LSMOD parameter.
250 target$ lsmod > /tmp/mylsmod
251 target$ scp /tmp/mylsmod host:/tmp
253 host$ make LSMOD=/tmp/mylsmod localmodconfig
255 The above also works when cross compiling.
257 "make localyesconfig" Similar to localmodconfig, except it will convert
258 all module options to built in (=y) options.
260 You can find more information on using the Linux kernel config tools
261 in Documentation/kbuild/kconfig.txt.
263 - NOTES on "make config":
265 - Having unnecessary drivers will make the kernel bigger, and can
266 under some circumstances lead to problems: probing for a
267 nonexistent controller card may confuse your other controllers
269 - A kernel with math-emulation compiled in will still use the
270 coprocessor if one is present: the math emulation will just
271 never get used in that case. The kernel will be slightly larger,
272 but will work on different machines regardless of whether they
273 have a math coprocessor or not.
275 - The "kernel hacking" configuration details usually result in a
276 bigger or slower kernel (or both), and can even make the kernel
277 less stable by configuring some routines to actively try to
278 break bad code to find kernel problems (kmalloc()). Thus you
279 should probably answer 'n' to the questions for "development",
280 "experimental", or "debugging" features.
282 COMPILING the kernel:
284 - Make sure you have at least gcc 3.2 available.
285 For more information, refer to Documentation/Changes.
287 Please note that you can still run a.out user programs with this kernel.
289 - Do a "make" to create a compressed kernel image. It is also
290 possible to do "make install" if you have lilo installed to suit the
291 kernel makefiles, but you may want to check your particular lilo setup first.
293 To do the actual install, you have to be root, but none of the normal
294 build should require that. Don't take the name of root in vain.
296 - If you configured any of the parts of the kernel as `modules', you
297 will also have to do "make modules_install".
299 - Verbose kernel compile/build output:
301 Normally, the kernel build system runs in a fairly quiet mode (but not
302 totally silent). However, sometimes you or other kernel developers need
303 to see compile, link, or other commands exactly as they are executed.
304 For this, use "verbose" build mode. This is done by passing
305 "V=1" to the "make" command, e.g.
309 To have the build system also tell the reason for the rebuild of each
310 target, use "V=2". The default is "V=0".
312 - Keep a backup kernel handy in case something goes wrong. This is
313 especially true for the development releases, since each new release
314 contains new code which has not been debugged. Make sure you keep a
315 backup of the modules corresponding to that kernel, as well. If you
316 are installing a new kernel with the same version number as your
317 working kernel, make a backup of your modules directory before you
318 do a "make modules_install".
320 Alternatively, before compiling, use the kernel config option
321 "LOCALVERSION" to append a unique suffix to the regular kernel version.
322 LOCALVERSION can be set in the "General Setup" menu.
324 - In order to boot your new kernel, you'll need to copy the kernel
325 image (e.g. .../linux/arch/x86/boot/bzImage after compilation)
326 to the place where your regular bootable kernel is found.
328 - Booting a kernel directly from a floppy without the assistance of a
329 bootloader such as LILO, is no longer supported.
331 If you boot Linux from the hard drive, chances are you use LILO, which
332 uses the kernel image as specified in the file /etc/lilo.conf. The
333 kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
334 /boot/bzImage. To use the new kernel, save a copy of the old image
335 and copy the new image over the old one. Then, you MUST RERUN LILO
336 to update the loading map! If you don't, you won't be able to boot
337 the new kernel image.
339 Reinstalling LILO is usually a matter of running /sbin/lilo.
340 You may wish to edit /etc/lilo.conf to specify an entry for your
341 old kernel image (say, /vmlinux.old) in case the new one does not
342 work. See the LILO docs for more information.
344 After reinstalling LILO, you should be all set. Shutdown the system,
347 If you ever need to change the default root device, video mode,
348 ramdisk size, etc. in the kernel image, use the 'rdev' program (or
349 alternatively the LILO boot options when appropriate). No need to
350 recompile the kernel to change these parameters.
352 - Reboot with the new kernel and enjoy.
354 IF SOMETHING GOES WRONG:
356 - If you have problems that seem to be due to kernel bugs, please check
357 the file MAINTAINERS to see if there is a particular person associated
358 with the part of the kernel that you are having trouble with. If there
359 isn't anyone listed there, then the second best thing is to mail
360 them to me (torvalds@linux-foundation.org), and possibly to any other
361 relevant mailing-list or to the newsgroup.
363 - In all bug-reports, *please* tell what kernel you are talking about,
364 how to duplicate the problem, and what your setup is (use your common
365 sense). If the problem is new, tell me so, and if the problem is
366 old, please try to tell me when you first noticed it.
368 - If the bug results in a message like
370 unable to handle kernel paging request at address C0000010
373 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
374 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
375 ds: xxxx es: xxxx fs: xxxx gs: xxxx
376 Pid: xx, process nr: xx
377 xx xx xx xx xx xx xx xx xx xx
379 or similar kernel debugging information on your screen or in your
380 system log, please duplicate it *exactly*. The dump may look
381 incomprehensible to you, but it does contain information that may
382 help debugging the problem. The text above the dump is also
383 important: it tells something about why the kernel dumped code (in
384 the above example, it's due to a bad kernel pointer). More information
385 on making sense of the dump is in Documentation/oops-tracing.txt
387 - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump
388 as is, otherwise you will have to use the "ksymoops" program to make
389 sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred).
390 This utility can be downloaded from
391 ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ .
392 Alternatively, you can do the dump lookup by hand:
394 - In debugging dumps like the above, it helps enormously if you can
395 look up what the EIP value means. The hex value as such doesn't help
396 me or anybody else very much: it will depend on your particular
397 kernel setup. What you should do is take the hex value from the EIP
398 line (ignore the "0010:"), and look it up in the kernel namelist to
399 see which kernel function contains the offending address.
401 To find out the kernel function name, you'll need to find the system
402 binary associated with the kernel that exhibited the symptom. This is
403 the file 'linux/vmlinux'. To extract the namelist and match it against
404 the EIP from the kernel crash, do:
406 nm vmlinux | sort | less
408 This will give you a list of kernel addresses sorted in ascending
409 order, from which it is simple to find the function that contains the
410 offending address. Note that the address given by the kernel
411 debugging messages will not necessarily match exactly with the
412 function addresses (in fact, that is very unlikely), so you can't
413 just 'grep' the list: the list will, however, give you the starting
414 point of each kernel function, so by looking for the function that
415 has a starting address lower than the one you are searching for but
416 is followed by a function with a higher address you will find the one
417 you want. In fact, it may be a good idea to include a bit of
418 "context" in your problem report, giving a few lines around the
421 If you for some reason cannot do the above (you have a pre-compiled
422 kernel image or similar), telling me as much about your setup as
423 possible will help. Please read the REPORTING-BUGS document for details.
425 - Alternatively, you can use gdb on a running kernel. (read-only; i.e. you
426 cannot change values or set break points.) To do this, first compile the
427 kernel with -g; edit arch/x86/Makefile appropriately, then do a "make
428 clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
430 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
431 You can now use all the usual gdb commands. The command to look up the
432 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
435 gdb'ing a non-running kernel currently fails because gdb (wrongly)
436 disregards the starting offset for which the kernel is compiled.