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 Unix clone written from scratch by Linus Torvalds with
10 assistance from a loosely-knit team of hackers across the Net.
11 It aims towards POSIX compliance.
13 It has all the features you would expect in a modern fully-fledged
14 Unix, including true multitasking, virtual memory, shared libraries,
15 demand loading, shared copy-on-write executables, proper memory
16 management and TCP/IP networking.
18 It is distributed under the GNU General Public License - see the
19 accompanying COPYING file for more details.
21 ON WHAT HARDWARE DOES IT RUN?
23 Linux was first developed for 386/486-based PCs. These days it also
24 runs on ARMs, DEC Alphas, SUN Sparcs, M68000 machines (like Atari and
25 Amiga), MIPS and PowerPC, and others.
29 - There is a lot of documentation available both in electronic form on
30 the Internet and in books, both Linux-specific and pertaining to
31 general UNIX questions. I'd recommend looking into the documentation
32 subdirectories on any Linux FTP site for the LDP (Linux Documentation
33 Project) books. This README is not meant to be documentation on the
34 system: there are much better sources available.
36 - There are various README files in the Documentation/ subdirectory:
37 these typically contain kernel-specific installation notes for some
38 drivers for example. See Documentation/00-INDEX for a list of what
39 is contained in each file. Please read the Changes file, as it
40 contains information about the problems, which may result by upgrading
43 - The Documentation/DocBook/ subdirectory contains several guides for
44 kernel developers and users. These guides can be rendered in a
45 number of formats: PostScript (.ps), PDF, and HTML, among others.
46 After installation, "make psdocs", "make pdfdocs", or "make htmldocs"
47 will render the documentation in the requested format.
49 INSTALLING the kernel:
51 - If you install the full sources, put the kernel tarball in a
52 directory where you have permissions (eg. your home directory) and
55 gzip -cd linux-2.6.XX.tar.gz | tar xvf -
58 bzip2 -dc linux-2.6.XX.tar.bz2 | tar xvf -
61 Replace "XX" with the version number of the latest kernel.
63 Do NOT use the /usr/src/linux area! This area has a (usually
64 incomplete) set of kernel headers that are used by the library header
65 files. They should match the library, and not get messed up by
66 whatever the kernel-du-jour happens to be.
68 - You can also upgrade between 2.6.xx releases by patching. Patches are
69 distributed in the traditional gzip and the new bzip2 format. To
70 install by patching, get all the newer patch files, enter the
71 top level directory of the kernel source (linux-2.6.xx) and execute:
73 gzip -cd ../patch-2.6.xx.gz | patch -p1
76 bzip2 -dc ../patch-2.6.xx.bz2 | patch -p1
78 (repeat xx for all versions bigger than the version of your current
79 source tree, _in_order_) and you should be ok. You may want to remove
80 the backup files (xxx~ or xxx.orig), and make sure that there are no
81 failed patches (xxx# or xxx.rej). If there are, either you or me has
84 Alternatively, the script patch-kernel can be used to automate this
85 process. It determines the current kernel version and applies any
88 linux/scripts/patch-kernel linux
90 The first argument in the command above is the location of the
91 kernel source. Patches are applied from the current directory, but
92 an alternative directory can be specified as the second argument.
94 - If you are upgrading between releases using the stable series patches
95 (for example, patch-2.6.xx.y), note that these "dot-releases" are
96 not incremental and must be applied to the 2.6.xx base tree. For
97 example, if your base kernel is 2.6.12 and you want to apply the
98 2.6.12.3 patch, you do not and indeed must not first apply the
99 2.6.12.1 and 2.6.12.2 patches. Similarly, if you are running kernel
100 version 2.6.12.2 and want to jump to 2.6.12.3, you must first
101 reverse the 2.6.12.2 patch (that is, patch -R) _before_ applying
104 - Make sure you have no stale .o files and dependencies lying around:
109 You should now have the sources correctly installed.
111 SOFTWARE REQUIREMENTS
113 Compiling and running the 2.6.xx kernels requires up-to-date
114 versions of various software packages. Consult
115 Documentation/Changes for the minimum version numbers required
116 and how to get updates for these packages. Beware that using
117 excessively old versions of these packages can cause indirect
118 errors that are very difficult to track down, so don't assume that
119 you can just update packages when obvious problems arise during
122 BUILD directory for the kernel:
124 When compiling the kernel all output files will per default be
125 stored together with the kernel source code.
126 Using the option "make O=output/dir" allow you to specify an alternate
127 place for the output files (including .config).
129 kernel source code: /usr/src/linux-2.6.N
130 build directory: /home/name/build/kernel
132 To configure and build the kernel use:
133 cd /usr/src/linux-2.6.N
134 make O=/home/name/build/kernel menuconfig
135 make O=/home/name/build/kernel
136 sudo make O=/home/name/build/kernel modules_install install
138 Please note: If the 'O=output/dir' option is used then it must be
139 used for all invocations of make.
141 CONFIGURING the kernel:
143 Do not skip this step even if you are only upgrading one minor
144 version. New configuration options are added in each release, and
145 odd problems will turn up if the configuration files are not set up
146 as expected. If you want to carry your existing configuration to a
147 new version with minimal work, use "make oldconfig", which will
148 only ask you for the answers to new questions.
150 - Alternate configuration commands are:
151 "make menuconfig" Text based color menus, radiolists & dialogs.
152 "make xconfig" X windows (Qt) based configuration tool.
153 "make gconfig" X windows (Gtk) based configuration tool.
154 "make oldconfig" Default all questions based on the contents of
155 your existing ./.config file.
156 "make silentoldconfig"
157 Like above, but avoids cluttering the screen
158 with questions already answered.
160 NOTES on "make config":
161 - having unnecessary drivers will make the kernel bigger, and can
162 under some circumstances lead to problems: probing for a
163 nonexistent controller card may confuse your other controllers
164 - compiling the kernel with "Processor type" set higher than 386
165 will result in a kernel that does NOT work on a 386. The
166 kernel will detect this on bootup, and give up.
167 - A kernel with math-emulation compiled in will still use the
168 coprocessor if one is present: the math emulation will just
169 never get used in that case. The kernel will be slightly larger,
170 but will work on different machines regardless of whether they
171 have a math coprocessor or not.
172 - the "kernel hacking" configuration details usually result in a
173 bigger or slower kernel (or both), and can even make the kernel
174 less stable by configuring some routines to actively try to
175 break bad code to find kernel problems (kmalloc()). Thus you
176 should probably answer 'n' to the questions for
177 "development", "experimental", or "debugging" features.
179 COMPILING the kernel:
181 - Make sure you have gcc 2.95.3 available.
182 gcc 2.91.66 (egcs-1.1.2), and gcc 2.7.2.3 are known to miscompile
183 some parts of the kernel, and are *no longer supported*.
184 Also remember to upgrade your binutils package (for as/ld/nm and company)
185 if necessary. For more information, refer to Documentation/Changes.
187 Please note that you can still run a.out user programs with this kernel.
189 - Do a "make" to create a compressed kernel image. It is also
190 possible to do "make install" if you have lilo installed to suit the
191 kernel makefiles, but you may want to check your particular lilo setup first.
193 To do the actual install you have to be root, but none of the normal
194 build should require that. Don't take the name of root in vain.
196 - If you configured any of the parts of the kernel as `modules', you
197 will also have to do "make modules_install".
199 - Keep a backup kernel handy in case something goes wrong. This is
200 especially true for the development releases, since each new release
201 contains new code which has not been debugged. Make sure you keep a
202 backup of the modules corresponding to that kernel, as well. If you
203 are installing a new kernel with the same version number as your
204 working kernel, make a backup of your modules directory before you
205 do a "make modules_install".
206 Alternatively, before compiling, use the kernel config option
207 "LOCALVERSION" to append a unique suffix to the regular kernel version.
208 LOCALVERSION can be set in the "General Setup" menu.
210 - In order to boot your new kernel, you'll need to copy the kernel
211 image (e.g. .../linux/arch/i386/boot/bzImage after compilation)
212 to the place where your regular bootable kernel is found.
214 - Booting a kernel directly from a floppy without the assistance of a
215 bootloader such as LILO, is no longer supported.
217 If you boot Linux from the hard drive, chances are you use LILO which
218 uses the kernel image as specified in the file /etc/lilo.conf. The
219 kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
220 /boot/bzImage. To use the new kernel, save a copy of the old image
221 and copy the new image over the old one. Then, you MUST RERUN LILO
222 to update the loading map!! If you don't, you won't be able to boot
223 the new kernel image.
225 Reinstalling LILO is usually a matter of running /sbin/lilo.
226 You may wish to edit /etc/lilo.conf to specify an entry for your
227 old kernel image (say, /vmlinux.old) in case the new one does not
228 work. See the LILO docs for more information.
230 After reinstalling LILO, you should be all set. Shutdown the system,
233 If you ever need to change the default root device, video mode,
234 ramdisk size, etc. in the kernel image, use the 'rdev' program (or
235 alternatively the LILO boot options when appropriate). No need to
236 recompile the kernel to change these parameters.
238 - Reboot with the new kernel and enjoy.
240 IF SOMETHING GOES WRONG:
242 - If you have problems that seem to be due to kernel bugs, please check
243 the file MAINTAINERS to see if there is a particular person associated
244 with the part of the kernel that you are having trouble with. If there
245 isn't anyone listed there, then the second best thing is to mail
246 them to me (torvalds@osdl.org), and possibly to any other relevant
247 mailing-list or to the newsgroup.
249 - In all bug-reports, *please* tell what kernel you are talking about,
250 how to duplicate the problem, and what your setup is (use your common
251 sense). If the problem is new, tell me so, and if the problem is
252 old, please try to tell me when you first noticed it.
254 - If the bug results in a message like
256 unable to handle kernel paging request at address C0000010
259 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
260 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
261 ds: xxxx es: xxxx fs: xxxx gs: xxxx
262 Pid: xx, process nr: xx
263 xx xx xx xx xx xx xx xx xx xx
265 or similar kernel debugging information on your screen or in your
266 system log, please duplicate it *exactly*. The dump may look
267 incomprehensible to you, but it does contain information that may
268 help debugging the problem. The text above the dump is also
269 important: it tells something about why the kernel dumped code (in
270 the above example it's due to a bad kernel pointer). More information
271 on making sense of the dump is in Documentation/oops-tracing.txt
273 - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump
274 as is, otherwise you will have to use the "ksymoops" program to make
275 sense of the dump. This utility can be downloaded from
276 ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops.
277 Alternately you can do the dump lookup by hand:
279 - In debugging dumps like the above, it helps enormously if you can
280 look up what the EIP value means. The hex value as such doesn't help
281 me or anybody else very much: it will depend on your particular
282 kernel setup. What you should do is take the hex value from the EIP
283 line (ignore the "0010:"), and look it up in the kernel namelist to
284 see which kernel function contains the offending address.
286 To find out the kernel function name, you'll need to find the system
287 binary associated with the kernel that exhibited the symptom. This is
288 the file 'linux/vmlinux'. To extract the namelist and match it against
289 the EIP from the kernel crash, do:
291 nm vmlinux | sort | less
293 This will give you a list of kernel addresses sorted in ascending
294 order, from which it is simple to find the function that contains the
295 offending address. Note that the address given by the kernel
296 debugging messages will not necessarily match exactly with the
297 function addresses (in fact, that is very unlikely), so you can't
298 just 'grep' the list: the list will, however, give you the starting
299 point of each kernel function, so by looking for the function that
300 has a starting address lower than the one you are searching for but
301 is followed by a function with a higher address you will find the one
302 you want. In fact, it may be a good idea to include a bit of
303 "context" in your problem report, giving a few lines around the
306 If you for some reason cannot do the above (you have a pre-compiled
307 kernel image or similar), telling me as much about your setup as
310 - Alternately, you can use gdb on a running kernel. (read-only; i.e. you
311 cannot change values or set break points.) To do this, first compile the
312 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
313 clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
315 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
316 You can now use all the usual gdb commands. The command to look up the
317 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
320 gdb'ing a non-running kernel currently fails because gdb (wrongly)
321 disregards the starting offset for which the kernel is compiled.