1 Linux kernel release 2.5.xx
3 These are the release notes for Linux version 2.5. 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 NOTE! As with all odd-numbered releases, 2.5.x is a development kernel.
8 For stable kernels, see the 2.4.x maintained by Marcelo Tosatti.
12 Linux is a Unix clone written from scratch by Linus Torvalds with
13 assistance from a loosely-knit team of hackers across the Net.
14 It aims towards POSIX compliance.
16 It has all the features you would expect in a modern fully-fledged
17 Unix, including true multitasking, virtual memory, shared libraries,
18 demand loading, shared copy-on-write executables, proper memory
19 management and TCP/IP networking.
21 It is distributed under the GNU General Public License - see the
22 accompanying COPYING file for more details.
24 ON WHAT HARDWARE DOES IT RUN?
26 Linux was first developed for 386/486-based PCs. These days it also
27 runs on ARMs, DEC Alphas, SUN Sparcs, M68000 machines (like Atari and
28 Amiga), MIPS and PowerPC, and others.
32 - There is a lot of documentation available both in electronic form on
33 the Internet and in books, both Linux-specific and pertaining to
34 general UNIX questions. I'd recommend looking into the documentation
35 subdirectories on any Linux FTP site for the LDP (Linux Documentation
36 Project) books. This README is not meant to be documentation on the
37 system: there are much better sources available.
39 - There are various README files in the Documentation/ subdirectory:
40 these typically contain kernel-specific installation notes for some
41 drivers for example. See ./Documentation/00-INDEX for a list of what
42 is contained in each file. Please read the Changes file, as it
43 contains information about the problems, which may result by upgrading
46 - The Documentation/DocBook/ subdirectory contains several guides for
47 kernel developers and users. These guides can be rendered in a
48 number of formats: PostScript (.ps), PDF, and HTML, among others.
49 After installation, "make psdocs", "make pdfdocs", or "make htmldocs"
50 will render the documentation in the requested format.
52 INSTALLING the kernel:
54 - If you install the full sources, put the kernel tarball in a
55 directory where you have permissions (eg. your home directory) and
58 gzip -cd linux-2.5.XX.tar.gz | tar xvf -
60 Replace "XX" with the version number of the latest kernel.
62 Do NOT use the /usr/src/linux area! This area has a (usually
63 incomplete) set of kernel headers that are used by the library header
64 files. They should match the library, and not get messed up by
65 whatever the kernel-du-jour happens to be.
67 - You can also upgrade between 2.5.xx releases by patching. Patches are
68 distributed in the traditional gzip and the new bzip2 format. To
69 install by patching, get all the newer patch files, enter the
70 top level directory of the kernel source (linux-2.5.xx) and execute:
72 gzip -cd ../patch-2.5.xx.gz | patch -p1
75 bzip2 -dc ../patch-2.5.xx.bz2 | patch -p1
77 (repeat xx for all versions bigger than the version of your current
78 source tree, _in_order_) and you should be ok. You may want to remove
79 the backup files (xxx~ or xxx.orig), and make sure that there are no
80 failed patches (xxx# or xxx.rej). If there are, either you or me has
83 Alternatively, the script patch-kernel can be used to automate this
84 process. It determines the current kernel version and applies any
87 linux/scripts/patch-kernel linux
89 The first argument in the command above is the location of the
90 kernel source. Patches are applied from the current directory, but
91 an alternative directory can be specified as the second argument.
93 - Make sure you have no stale .o files and dependencies lying around:
98 You should now have the sources correctly installed.
100 SOFTWARE REQUIREMENTS
102 Compiling and running the 2.5.xx kernels requires up-to-date
103 versions of various software packages. Consult
104 ./Documentation/Changes for the minimum version numbers required
105 and how to get updates for these packages. Beware that using
106 excessively old versions of these packages can cause indirect
107 errors that are very difficult to track down, so don't assume that
108 you can just update packages when obvious problems arise during
111 BUILD directory for the kernel:
113 When compiling the kernel all output files will per default be
114 stored together with the kernel source code.
115 Using the option "make O=output/dir" allow you to specify an alternate
116 place for the output files (including .config).
118 kernel source code: /usr/src/linux-2.6.N
119 build directory: /home/name/build/kernel
121 To configure and build the kernel use:
122 cd /usr/src/linux-2.6.N
123 make O=/home/name/build/kernel menuconfig
124 make O=/home/name/build/kernel
125 sudo make O=/home/name/build/kernel install_modules install
127 Please note: If the 'O=output/dir' option is used then it must be
128 used for all invocations of make.
130 CONFIGURING the kernel:
132 Do not skip this step even if you are only upgrading one minor
133 version. New configuration options are added in each release, and
134 odd problems will turn up if the configuration files are not set up
135 as expected. If you want to carry your existing configuration to a
136 new version with minimal work, use "make oldconfig", which will
137 only ask you for the answers to new questions.
139 - Alternate configuration commands are:
140 "make menuconfig" Text based color menus, radiolists & dialogs.
141 "make xconfig" X windows (Qt) based configuration tool.
142 "make gconfig" X windows (Gtk) based configuration tool.
143 "make oldconfig" Default all questions based on the contents of
144 your existing ./.config file.
146 NOTES on "make config":
147 - having unnecessary drivers will make the kernel bigger, and can
148 under some circumstances lead to problems: probing for a
149 nonexistent controller card may confuse your other controllers
150 - compiling the kernel with "Processor type" set higher than 386
151 will result in a kernel that does NOT work on a 386. The
152 kernel will detect this on bootup, and give up.
153 - A kernel with math-emulation compiled in will still use the
154 coprocessor if one is present: the math emulation will just
155 never get used in that case. The kernel will be slightly larger,
156 but will work on different machines regardless of whether they
157 have a math coprocessor or not.
158 - the "kernel hacking" configuration details usually result in a
159 bigger or slower kernel (or both), and can even make the kernel
160 less stable by configuring some routines to actively try to
161 break bad code to find kernel problems (kmalloc()). Thus you
162 should probably answer 'n' to the questions for
163 "development", "experimental", or "debugging" features.
165 - Check the top Makefile for further site-dependent configuration
166 (default SVGA mode etc).
168 COMPILING the kernel:
170 - Make sure you have gcc 2.95.3 available.
171 gcc 2.91.66 (egcs-1.1.2), and gcc 2.7.2.3 are known to miscompile
172 some parts of the kernel, and are *no longer supported*.
173 Also remember to upgrade your binutils package (for as/ld/nm and company)
174 if necessary. For more information, refer to ./Documentation/Changes.
176 Please note that you can still run a.out user programs with this kernel.
178 - Do a "make bzImage" to create a compressed kernel image. If you want
179 to make a boot disk (without root filesystem or LILO), insert a floppy
180 in your A: drive, and do a "make bzdisk". It is also possible to do
181 "make install" if you have lilo installed to suit the kernel makefiles,
182 but you may want to check your particular lilo setup first.
184 To do the actual install you have to be root, but none of the normal
185 build should require that. Don't take the name of root in vain.
187 - In the unlikely event that your system cannot boot bzImage kernels you
188 can still compile your kernel as zImage. However, since zImage support
189 will be removed at some point in the future in favor of bzImage we
190 encourage people having problems with booting bzImage kernels to report
191 these, with detailed hardware configuration information, to the
192 linux-kernel mailing list and to H. Peter Anvin <hpa+linux@zytor.com>.
194 - If you configured any of the parts of the kernel as `modules', you
195 will have to do "make modules" followed by "make modules_install".
196 Read Documentation/modules.txt for more information. For example,
197 an explanation of how to use the modules is included there.
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".
207 - In order to boot your new kernel, you'll need to copy the kernel
208 image (found in .../linux/arch/i386/boot/bzImage after compilation)
209 to the place where your regular bootable kernel is found.
211 For some, this is on a floppy disk, in which case you can copy the
212 kernel bzImage file to /dev/fd0 to make a bootable floppy.
214 If you boot Linux from the hard drive, chances are you use LILO which
215 uses the kernel image as specified in the file /etc/lilo.conf. The
216 kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
217 /boot/bzImage. To use the new kernel, save a copy of the old image
218 and copy the new image over the old one. Then, you MUST RERUN LILO
219 to update the loading map!! If you don't, you won't be able to boot
220 the new kernel image.
222 Reinstalling LILO is usually a matter of running /sbin/lilo.
223 You may wish to edit /etc/lilo.conf to specify an entry for your
224 old kernel image (say, /vmlinux.old) in case the new one does not
225 work. See the LILO docs for more information.
227 After reinstalling LILO, you should be all set. Shutdown the system,
230 If you ever need to change the default root device, video mode,
231 ramdisk size, etc. in the kernel image, use the 'rdev' program (or
232 alternatively the LILO boot options when appropriate). No need to
233 recompile the kernel to change these parameters.
235 - Reboot with the new kernel and enjoy.
237 IF SOMETHING GOES WRONG:
239 - If you have problems that seem to be due to kernel bugs, please check
240 the file MAINTAINERS to see if there is a particular person associated
241 with the part of the kernel that you are having trouble with. If there
242 isn't anyone listed there, then the second best thing is to mail
243 them to me (torvalds@osdl.org), and possibly to any other relevant
244 mailing-list or to the newsgroup.
246 - In all bug-reports, *please* tell what kernel you are talking about,
247 how to duplicate the problem, and what your setup is (use your common
248 sense). If the problem is new, tell me so, and if the problem is
249 old, please try to tell me when you first noticed it.
251 - If the bug results in a message like
253 unable to handle kernel paging request at address C0000010
256 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
257 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
258 ds: xxxx es: xxxx fs: xxxx gs: xxxx
259 Pid: xx, process nr: xx
260 xx xx xx xx xx xx xx xx xx xx
262 or similar kernel debugging information on your screen or in your
263 system log, please duplicate it *exactly*. The dump may look
264 incomprehensible to you, but it does contain information that may
265 help debugging the problem. The text above the dump is also
266 important: it tells something about why the kernel dumped code (in
267 the above example it's due to a bad kernel pointer). More information
268 on making sense of the dump is in Documentation/oops-tracing.txt
270 - You can use the "ksymoops" program to make sense of the dump. This
271 utility can be downloaded from
272 ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops.
273 Alternately you can do the dump lookup by hand:
275 - In debugging dumps like the above, it helps enormously if you can
276 look up what the EIP value means. The hex value as such doesn't help
277 me or anybody else very much: it will depend on your particular
278 kernel setup. What you should do is take the hex value from the EIP
279 line (ignore the "0010:"), and look it up in the kernel namelist to
280 see which kernel function contains the offending address.
282 To find out the kernel function name, you'll need to find the system
283 binary associated with the kernel that exhibited the symptom. This is
284 the file 'linux/vmlinux'. To extract the namelist and match it against
285 the EIP from the kernel crash, do:
287 nm vmlinux | sort | less
289 This will give you a list of kernel addresses sorted in ascending
290 order, from which it is simple to find the function that contains the
291 offending address. Note that the address given by the kernel
292 debugging messages will not necessarily match exactly with the
293 function addresses (in fact, that is very unlikely), so you can't
294 just 'grep' the list: the list will, however, give you the starting
295 point of each kernel function, so by looking for the function that
296 has a starting address lower than the one you are searching for but
297 is followed by a function with a higher address you will find the one
298 you want. In fact, it may be a good idea to include a bit of
299 "context" in your problem report, giving a few lines around the
302 If you for some reason cannot do the above (you have a pre-compiled
303 kernel image or similar), telling me as much about your setup as
306 - Alternately, you can use gdb on a running kernel. (read-only; i.e. you
307 cannot change values or set break points.) To do this, first compile the
308 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
309 clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
311 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
312 You can now use all the usual gdb commands. The command to look up the
313 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
316 gdb'ing a non-running kernel currently fails because gdb (wrongly)
317 disregards the starting offset for which the kernel is compiled.