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1 Linux kernel release 2.3.xx
3 These are the release notes for Linux version 2.3. 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 Linux version 2.3 is a DEVELOPMENT kernel, and not intended for general
8 public use. Different releases may have various and sometimes severe
9 bugs. It is *strongly* recommended that you back up the previous kernel
10 before installing any new 2.3.xx release.
12 If you need to use a proven and stable Linux kernel, please use 2.0.37
13 or 2.2.xx. All features which will be in the 2.3.xx releases will be
14 contained in 2.4.xx when the code base has stabilized again.
16 If you decide to use 2.3, it is recommended that you join the kernel mailing
17 list. To do this, e-mail majordomo@vger.rutgers.edu, and put in the body
18 of the message "subscribe linux-kernel" or "subscribe linux-kernel-digest"
19 for a daily digest of the mailing list (it is a high-traffic list.)
21 However, please make sure you don't ask questions which are already answered
22 in various files in the Documentation directory. See DOCUMENTATION below.
24 WHAT IS LINUX?
26 Linux is a Unix clone written from scratch by Linus Torvalds with
27 assistance from a loosely-knit team of hackers across the Net.
28 It aims towards POSIX compliance.
30 It has all the features you would expect in a modern fully-fledged
31 Unix, including true multitasking, virtual memory, shared libraries,
32 demand loading, shared copy-on-write executables, proper memory
33 management and TCP/IP networking.
35 It is distributed under the GNU General Public License - see the
36 accompanying COPYING file for more details.
38 ON WHAT HARDWARE DOES IT RUN?
40 Linux was first developed for 386/486-based PCs. These days it also
41 runs on ARMs, DEC Alphas, SUN Sparcs, M68000 machines (like Atari and
42 Amiga), MIPS and PowerPC, and others.
44 DOCUMENTATION:
46 - There is a lot of documentation available both in electronic form on
47 the Internet and in books, both Linux-specific and pertaining to
48 general UNIX questions. I'd recommend looking into the documentation
49 subdirectories on any Linux FTP site for the LDP (Linux Documentation
50 Project) books. This README is not meant to be documentation on the
51 system: there are much better sources available.
53 - There are various README files in the Documentation/ subdirectory:
54 these typically contain kernel-specific installation notes for some
55 drivers for example. See ./Documentation/00-INDEX for a list of what
56 is contained in each file. Please read the Changes file, as it
57 contains information about the problems, which may result by upgrading
58 your kernel.
60 INSTALLING the kernel:
62 - If you install the full sources, do a
64 cd /usr/src
65 gzip -cd linux-2.3.XX.tar.gz | tar xvf -
67 to get it all put in place. Replace "XX" with the version number of the
68 latest kernel.
70 - You can also upgrade between 2.3.xx releases by patching. Patches are
71 distributed in the traditional gzip and the new bzip2 format. To
72 install by patching, get all the newer patch files and do
74 cd /usr/src
75 gzip -cd patchXX.gz | patch -p0
77 or
78 cd /usr/src
79 bzip2 -dc patchXX.bz2 | patch -p0
81 (repeat xx for all versions bigger than the version of your current
82 source tree, _in_order_) and you should be ok. You may want to remove
83 the backup files (xxx~ or xxx.orig), and make sure that there are no
84 failed patches (xxx# or xxx.rej). If there are, either you or me has
85 made a mistake.
87 Alternatively, the script patch-kernel can be used to automate this
88 process. It determines the current kernel version and applies any
89 patches found.
91 cd /usr/src
92 linux/scripts/patch-kernel
94 The default directory for the kernel source is /usr/src/linux, but
95 can be specified as the first argument. Patches are applied from
96 the current directory, but an alternative directory can be specified
97 as the second argument.
99 - Make sure you have no stale .o files and dependencies lying around:
101 cd /usr/src/linux
102 make mrproper
104 You should now have the sources correctly installed.
106 SOFTWARE REQUIREMENTS
108 Compiling and running the 2.3.xx kernels requires up-to-date
109 versions of various software packages. Consult
110 ./Documentation/Changes for the minimum version numbers required
111 and how to get updates for these packages. Beware that using
112 excessively old versions of these packages can cause indirect
113 errors that are very difficult to track down, so don't assume that
114 you can just update packages when obvious problems arise during
115 build or operation.
117 CONFIGURING the kernel:
119 - Do a "make config" to configure the basic kernel. "make config" needs
120 bash to work: it will search for bash in $BASH, /bin/bash and /bin/sh
121 (in that order), so one of those must be correct for it to work.
123 Do not skip this step even if you are only upgrading one minor
124 version. New configuration options are added in each release, and
125 odd problems will turn up if the configuration files are not set up
126 as expected. If you want to carry your existing configuration to a
127 new version with minimal work, use "make oldconfig", which will
128 only ask you for the answers to new questions.
130 - Alternate configuration commands are:
131 "make menuconfig" Text based color menus, radiolists & dialogs.
132 "make xconfig" X windows based configuration tool.
133 "make oldconfig" Default all questions based on the contents of
134 your existing ./.config file.
136 NOTES on "make config":
137 - having unnecessary drivers will make the kernel bigger, and can
138 under some circumstances lead to problems: probing for a
139 nonexistent controller card may confuse your other controllers
140 - compiling the kernel with "Processor type" set higher than 386
141 will result in a kernel that does NOT work on a 386. The
142 kernel will detect this on bootup, and give up.
143 - A kernel with math-emulation compiled in will still use the
144 coprocessor if one is present: the math emulation will just
145 never get used in that case. The kernel will be slightly larger,
146 but will work on different machines regardless of whether they
147 have a math coprocessor or not.
148 - the "kernel hacking" configuration details usually result in a
149 bigger or slower kernel (or both), and can even make the kernel
150 less stable by configuring some routines to actively try to
151 break bad code to find kernel problems (kmalloc()). Thus you
152 should probably answer 'n' to the questions for
153 "development", "experimental", or "debugging" features.
155 - Check the top Makefile for further site-dependent configuration
156 (default SVGA mode etc).
158 - Finally, do a "make dep" to set up all the dependencies correctly.
160 COMPILING the kernel:
162 - Make sure you have gcc-2.7.2 or newer available. It seems older gcc
163 versions can have problems compiling newer versions of Linux. This
164 is mainly because the older compilers can only generate "a.out"-format
165 executables. As of Linux 2.1.0, the kernel must be compiled as an
166 "ELF" binary. If you upgrade your compiler, remember to get the new
167 binutils package too (for as/ld/nm and company).
169 Please note that you can still run a.out user programs with this
170 kernel.
172 - Do a "make zImage" to create a compressed kernel image. If you want
173 to make a boot disk (without root filesystem or LILO), insert a floppy
174 in your A: drive, and do a "make zdisk". It is also possible to do
175 "make zlilo" if you have lilo installed to suit the kernel makefiles,
176 but you may want to check your particular lilo setup first.
178 - If your kernel is too large for "make zImage", use "make bzImage"
179 instead.
181 - If you configured any of the parts of the kernel as `modules', you
182 will have to do "make modules" followed by "make modules_install".
183 Read Documentation/modules.txt for more information. For example,
184 an explanation of how to use the modules is included there.
186 - Keep a backup kernel handy in case something goes wrong. This is
187 especially true for the development releases, since each new release
188 contains new code which has not been debugged. Make sure you keep a
189 backup of the modules corresponding to that kernel, as well. If you
190 are installing a new kernel with the same version number as your
191 working kernel, make a backup of your modules directory before you
192 do a "make modules_install".
194 - In order to boot your new kernel, you'll need to copy the kernel
195 image (found in /usr/src/linux/arch/i386/boot/zImage after compilation)
196 to the place where your regular bootable kernel is found.
198 For some, this is on a floppy disk, in which case you can "cp
199 /usr/src/linux/arch/i386/boot/zImage /dev/fd0" to make a bootable
200 floppy. Please note that you can not boot a kernel by
201 directly dumping it to a 720k double-density 3.5" floppy. In this
202 case, it is highly recommended that you install LILO on your
203 double-density boot floppy or switch to high-density floppies.
205 If you boot Linux from the hard drive, chances are you use LILO which
206 uses the kernel image as specified in the file /etc/lilo.conf. The
207 kernel image file is usually /vmlinuz, or /zImage, or /etc/zImage.
208 To use the new kernel, save a copy of the old image and copy the new
209 image over the old one. Then, you MUST RERUN LILO to update the
210 loading map!! If you don't, you won't be able to boot the new kernel
211 image.
213 Reinstalling LILO is usually a matter of running /sbin/lilo.
214 You may wish to edit /etc/lilo.conf to specify an entry for your
215 old kernel image (say, /vmlinux.old) in case the new one does not
216 work. See the LILO docs for more information.
218 After reinstalling LILO, you should be all set. Shutdown the system,
219 reboot, and enjoy!
221 If you ever need to change the default root device, video mode,
222 ramdisk size, etc. in the kernel image, use the 'rdev' program (or
223 alternatively the LILO boot options when appropriate). No need to
224 recompile the kernel to change these parameters.
226 - Reboot with the new kernel and enjoy.
228 IF SOMETHING GOES WRONG:
230 - If you have problems that seem to be due to kernel bugs, please check
231 the file MAINTAINERS to see if there is a particular person associated
232 with the part of the kernel that you are having trouble with. If there
233 isn't anyone listed there, then the second best thing is to mail
234 them to me (torvalds@transmeta.com), and possibly to any other
235 relevant mailing-list or to the newsgroup. The mailing-lists are
236 useful especially for SCSI and networking problems, as I can't test
237 either of those personally anyway.
239 - In all bug-reports, *please* tell what kernel you are talking about,
240 how to duplicate the problem, and what your setup is (use your common
241 sense). If the problem is new, tell me so, and if the problem is
242 old, please try to tell me when you first noticed it.
244 - If the bug results in a message like
246 unable to handle kernel paging request at address C0000010
247 Oops: 0002
248 EIP: 0010:XXXXXXXX
249 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
250 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
251 ds: xxxx es: xxxx fs: xxxx gs: xxxx
252 Pid: xx, process nr: xx
253 xx xx xx xx xx xx xx xx xx xx
255 or similar kernel debugging information on your screen or in your
256 system log, please duplicate it *exactly*. The dump may look
257 incomprehensible to you, but it does contain information that may
258 help debugging the problem. The text above the dump is also
259 important: it tells something about why the kernel dumped code (in
260 the above example it's due to a bad kernel pointer). More information
261 on making sense of the dump is in Documentation/oops-tracing.txt
263 - You can use the "ksymoops" program to make sense of the dump. Find
264 the C++ sources under the scripts/ directory to avoid having to do
265 the dump lookup by hand:
267 - In debugging dumps like the above, it helps enormously if you can
268 look up what the EIP value means. The hex value as such doesn't help
269 me or anybody else very much: it will depend on your particular
270 kernel setup. What you should do is take the hex value from the EIP
271 line (ignore the "0010:"), and look it up in the kernel namelist to
272 see which kernel function contains the offending address.
274 To find out the kernel function name, you'll need to find the system
275 binary associated with the kernel that exhibited the symptom. This is
276 the file 'linux/vmlinux'. To extract the namelist and match it against
277 the EIP from the kernel crash, do:
279 nm vmlinux | sort | less
281 This will give you a list of kernel addresses sorted in ascending
282 order, from which it is simple to find the function that contains the
283 offending address. Note that the address given by the kernel
284 debugging messages will not necessarily match exactly with the
285 function addresses (in fact, that is very unlikely), so you can't
286 just 'grep' the list: the list will, however, give you the starting
287 point of each kernel function, so by looking for the function that
288 has a starting address lower than the one you are searching for but
289 is followed by a function with a higher address you will find the one
290 you want. In fact, it may be a good idea to include a bit of
291 "context" in your problem report, giving a few lines around the
292 interesting one.
294 If you for some reason cannot do the above (you have a pre-compiled
295 kernel image or similar), telling me as much about your setup as
296 possible will help.
298 - Alternately, you can use gdb on a running kernel. (read-only; i.e. you
299 cannot change values or set break points.) To do this, first compile the
300 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
301 clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
303 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
304 You can now use all the usual gdb commands. The command to look up the
305 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
306 with the EIP value.)
308 gdb'ing a non-running kernel currently fails because gdb (wrongly)
309 disregards the starting offset for which the kernel is compiled.