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 -
57 Replace "XX" with the version number of the latest kernel.
59 Do NOT use the /usr/src/linux area! This area has a (usually
60 incomplete) set of kernel headers that are used by the library header
61 files. They should match the library, and not get messed up by
62 whatever the kernel-du-jour happens to be.
64 - You can also upgrade between 2.6.xx releases by patching. Patches are
65 distributed in the traditional gzip and the new bzip2 format. To
66 install by patching, get all the newer patch files, enter the
67 top level directory of the kernel source (linux-2.6.xx) and execute:
69 gzip -cd ../patch-2.6.xx.gz | patch -p1
72 bzip2 -dc ../patch-2.6.xx.bz2 | patch -p1
74 (repeat xx for all versions bigger than the version of your current
75 source tree, _in_order_) and you should be ok. You may want to remove
76 the backup files (xxx~ or xxx.orig), and make sure that there are no
77 failed patches (xxx# or xxx.rej). If there are, either you or me has
80 Alternatively, the script patch-kernel can be used to automate this
81 process. It determines the current kernel version and applies any
84 linux/scripts/patch-kernel linux
86 The first argument in the command above is the location of the
87 kernel source. Patches are applied from the current directory, but
88 an alternative directory can be specified as the second argument.
90 - Make sure you have no stale .o files and dependencies lying around:
95 You should now have the sources correctly installed.
99 Compiling and running the 2.6.xx kernels requires up-to-date
100 versions of various software packages. Consult
101 ./Documentation/Changes for the minimum version numbers required
102 and how to get updates for these packages. Beware that using
103 excessively old versions of these packages can cause indirect
104 errors that are very difficult to track down, so don't assume that
105 you can just update packages when obvious problems arise during
108 BUILD directory for the kernel:
110 When compiling the kernel all output files will per default be
111 stored together with the kernel source code.
112 Using the option "make O=output/dir" allow you to specify an alternate
113 place for the output files (including .config).
115 kernel source code: /usr/src/linux-2.6.N
116 build directory: /home/name/build/kernel
118 To configure and build the kernel use:
119 cd /usr/src/linux-2.6.N
120 make O=/home/name/build/kernel menuconfig
121 make O=/home/name/build/kernel
122 sudo make O=/home/name/build/kernel install_modules install
124 Please note: If the 'O=output/dir' option is used then it must be
125 used for all invocations of make.
127 CONFIGURING the kernel:
129 Do not skip this step even if you are only upgrading one minor
130 version. New configuration options are added in each release, and
131 odd problems will turn up if the configuration files are not set up
132 as expected. If you want to carry your existing configuration to a
133 new version with minimal work, use "make oldconfig", which will
134 only ask you for the answers to new questions.
136 - Alternate configuration commands are:
137 "make menuconfig" Text based color menus, radiolists & dialogs.
138 "make xconfig" X windows (Qt) based configuration tool.
139 "make gconfig" X windows (Gtk) based configuration tool.
140 "make oldconfig" Default all questions based on the contents of
141 your existing ./.config file.
143 NOTES on "make config":
144 - having unnecessary drivers will make the kernel bigger, and can
145 under some circumstances lead to problems: probing for a
146 nonexistent controller card may confuse your other controllers
147 - compiling the kernel with "Processor type" set higher than 386
148 will result in a kernel that does NOT work on a 386. The
149 kernel will detect this on bootup, and give up.
150 - A kernel with math-emulation compiled in will still use the
151 coprocessor if one is present: the math emulation will just
152 never get used in that case. The kernel will be slightly larger,
153 but will work on different machines regardless of whether they
154 have a math coprocessor or not.
155 - the "kernel hacking" configuration details usually result in a
156 bigger or slower kernel (or both), and can even make the kernel
157 less stable by configuring some routines to actively try to
158 break bad code to find kernel problems (kmalloc()). Thus you
159 should probably answer 'n' to the questions for
160 "development", "experimental", or "debugging" features.
162 - Check the top Makefile for further site-dependent configuration
163 (default SVGA mode etc).
165 COMPILING the kernel:
167 - Make sure you have gcc 2.95.3 available.
168 gcc 2.91.66 (egcs-1.1.2), and gcc 2.7.2.3 are known to miscompile
169 some parts of the kernel, and are *no longer supported*.
170 Also remember to upgrade your binutils package (for as/ld/nm and company)
171 if necessary. For more information, refer to ./Documentation/Changes.
173 Please note that you can still run a.out user programs with this kernel.
175 - Do a "make bzImage" to create a compressed kernel image. If you want
176 to make a boot disk (without root filesystem or LILO), insert a floppy
177 in your A: drive, and do a "make bzdisk". It is also possible to do
178 "make install" if you have lilo installed to suit the kernel makefiles,
179 but you may want to check your particular lilo setup first.
181 To do the actual install you have to be root, but none of the normal
182 build should require that. Don't take the name of root in vain.
184 - In the unlikely event that your system cannot boot bzImage kernels you
185 can still compile your kernel as zImage. However, since zImage support
186 will be removed at some point in the future in favor of bzImage we
187 encourage people having problems with booting bzImage kernels to report
188 these, with detailed hardware configuration information, to the
189 linux-kernel mailing list and to H. Peter Anvin <hpa+linux@zytor.com>.
191 - If you configured any of the parts of the kernel as `modules', you
192 will have to do "make modules" followed by "make modules_install".
194 - Keep a backup kernel handy in case something goes wrong. This is
195 especially true for the development releases, since each new release
196 contains new code which has not been debugged. Make sure you keep a
197 backup of the modules corresponding to that kernel, as well. If you
198 are installing a new kernel with the same version number as your
199 working kernel, make a backup of your modules directory before you
200 do a "make modules_install".
202 - In order to boot your new kernel, you'll need to copy the kernel
203 image (found in .../linux/arch/i386/boot/bzImage after compilation)
204 to the place where your regular bootable kernel is found.
206 For some, this is on a floppy disk, in which case you can copy the
207 kernel bzImage file to /dev/fd0 to make a bootable floppy.
209 If you boot Linux from the hard drive, chances are you use LILO which
210 uses the kernel image as specified in the file /etc/lilo.conf. The
211 kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
212 /boot/bzImage. To use the new kernel, save a copy of the old image
213 and copy the new image over the old one. Then, you MUST RERUN LILO
214 to update the loading map!! If you don't, you won't be able to boot
215 the new kernel image.
217 Reinstalling LILO is usually a matter of running /sbin/lilo.
218 You may wish to edit /etc/lilo.conf to specify an entry for your
219 old kernel image (say, /vmlinux.old) in case the new one does not
220 work. See the LILO docs for more information.
222 After reinstalling LILO, you should be all set. Shutdown the system,
225 If you ever need to change the default root device, video mode,
226 ramdisk size, etc. in the kernel image, use the 'rdev' program (or
227 alternatively the LILO boot options when appropriate). No need to
228 recompile the kernel to change these parameters.
230 - Reboot with the new kernel and enjoy.
232 IF SOMETHING GOES WRONG:
234 - If you have problems that seem to be due to kernel bugs, please check
235 the file MAINTAINERS to see if there is a particular person associated
236 with the part of the kernel that you are having trouble with. If there
237 isn't anyone listed there, then the second best thing is to mail
238 them to me (torvalds@osdl.org), and possibly to any other relevant
239 mailing-list or to the newsgroup.
241 - In all bug-reports, *please* tell what kernel you are talking about,
242 how to duplicate the problem, and what your setup is (use your common
243 sense). If the problem is new, tell me so, and if the problem is
244 old, please try to tell me when you first noticed it.
246 - If the bug results in a message like
248 unable to handle kernel paging request at address C0000010
251 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
252 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
253 ds: xxxx es: xxxx fs: xxxx gs: xxxx
254 Pid: xx, process nr: xx
255 xx xx xx xx xx xx xx xx xx xx
257 or similar kernel debugging information on your screen or in your
258 system log, please duplicate it *exactly*. The dump may look
259 incomprehensible to you, but it does contain information that may
260 help debugging the problem. The text above the dump is also
261 important: it tells something about why the kernel dumped code (in
262 the above example it's due to a bad kernel pointer). More information
263 on making sense of the dump is in Documentation/oops-tracing.txt
265 - You can use the "ksymoops" program to make sense of the dump. This
266 utility can be downloaded from
267 ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops.
268 Alternately you can do the dump lookup by hand:
270 - In debugging dumps like the above, it helps enormously if you can
271 look up what the EIP value means. The hex value as such doesn't help
272 me or anybody else very much: it will depend on your particular
273 kernel setup. What you should do is take the hex value from the EIP
274 line (ignore the "0010:"), and look it up in the kernel namelist to
275 see which kernel function contains the offending address.
277 To find out the kernel function name, you'll need to find the system
278 binary associated with the kernel that exhibited the symptom. This is
279 the file 'linux/vmlinux'. To extract the namelist and match it against
280 the EIP from the kernel crash, do:
282 nm vmlinux | sort | less
284 This will give you a list of kernel addresses sorted in ascending
285 order, from which it is simple to find the function that contains the
286 offending address. Note that the address given by the kernel
287 debugging messages will not necessarily match exactly with the
288 function addresses (in fact, that is very unlikely), so you can't
289 just 'grep' the list: the list will, however, give you the starting
290 point of each kernel function, so by looking for the function that
291 has a starting address lower than the one you are searching for but
292 is followed by a function with a higher address you will find the one
293 you want. In fact, it may be a good idea to include a bit of
294 "context" in your problem report, giving a few lines around the
297 If you for some reason cannot do the above (you have a pre-compiled
298 kernel image or similar), telling me as much about your setup as
301 - Alternately, you can use gdb on a running kernel. (read-only; i.e. you
302 cannot change values or set break points.) To do this, first compile the
303 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
304 clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
306 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
307 You can now use all the usual gdb commands. The command to look up the
308 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
311 gdb'ing a non-running kernel currently fails because gdb (wrongly)
312 disregards the starting offset for which the kernel is compiled.