1 Linux kernel release 2.4.xx
2
3These are the release notes for Linux version 2.4. Read them carefully,
4as they tell you what this is all about, explain how to install the
5kernel, and what to do if something goes wrong.
6
7WHAT IS LINUX?
8
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.
12
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.
17
18 It is distributed under the GNU General Public License - see the
19 accompanying COPYING file for more details.
20
21ON WHAT HARDWARE DOES IT RUN?
22
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.
26
27DOCUMENTATION:
28
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.
35
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
41 your kernel.
42
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.
48
49INSTALLING the kernel:
50
51 - If you install the full sources, put the kernel tarball in a
52 directory where you have permissions (eg. your home directory) and
53 unpack it:
54
55 gzip -cd linux-2.4.XX.tar.gz | tar xvf -
56
57 Replace "XX" with the version number of the latest kernel.
58
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.
63
64 - You can also upgrade between 2.4.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 directory in which you unpacked the kernel source and execute:
68
69 gzip -cd patchXX.gz | patch -p0
70
71 or
72 bzip2 -dc patchXX.bz2 | patch -p0
73
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
78 made a mistake.
79
80 Alternatively, the script patch-kernel can be used to automate this
81 process. It determines the current kernel version and applies any
82 patches found.
83
84 linux/scripts/patch-kernel linux
85
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.
89
90 - Make sure you have no stale .o files and dependencies lying around:
91
92 cd linux
93 make mrproper
94
95 You should now have the sources correctly installed.
96
97SOFTWARE REQUIREMENTS
98
99 Compiling and running the 2.4.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
106 build or operation.
107
108CONFIGURING the kernel:
109
110 - Do a "make config" to configure the basic kernel. "make config" needs
111 bash to work: it will search for bash in $BASH, /bin/bash and /bin/sh
112 (in that order), so one of those must be correct for it to work.
113
114 Do not skip this step even if you are only upgrading one minor
115 version. New configuration options are added in each release, and
116 odd problems will turn up if the configuration files are not set up
117 as expected. If you want to carry your existing configuration to a
118 new version with minimal work, use "make oldconfig", which will
119 only ask you for the answers to new questions.
120
121 - Alternate configuration commands are:
122 "make menuconfig" Text based color menus, radiolists & dialogs.
123 "make xconfig" X windows based configuration tool.
124 "make oldconfig" Default all questions based on the contents of
125 your existing ./.config file.
126
127 NOTES on "make config":
128 - having unnecessary drivers will make the kernel bigger, and can
129 under some circumstances lead to problems: probing for a
130 nonexistent controller card may confuse your other controllers
131 - compiling the kernel with "Processor type" set higher than 386
132 will result in a kernel that does NOT work on a 386. The
133 kernel will detect this on bootup, and give up.
134 - A kernel with math-emulation compiled in will still use the
135 coprocessor if one is present: the math emulation will just
136 never get used in that case. The kernel will be slightly larger,
137 but will work on different machines regardless of whether they
138 have a math coprocessor or not.
139 - the "kernel hacking" configuration details usually result in a
140 bigger or slower kernel (or both), and can even make the kernel
141 less stable by configuring some routines to actively try to
142 break bad code to find kernel problems (kmalloc()). Thus you
143 should probably answer 'n' to the questions for
144 "development", "experimental", or "debugging" features.
145
146 - Check the top Makefile for further site-dependent configuration
147 (default SVGA mode etc).
148
149 - Finally, do a "make dep" to set up all the dependencies correctly.
150
151COMPILING the kernel:
152
153 - Make sure you have gcc 2.95.3 available. gcc 2.91.66 (egcs-1.1.2) may
154 also work but is not as safe, and *gcc 2.7.2.3 is no longer supported*.
155 Also remember to upgrade your binutils package (for as/ld/nm and company)
156 if necessary. For more information, refer to ./Documentation/Changes.
157
158 Please note that you can still run a.out user programs with this kernel.
159
160 - Do a "make bzImage" to create a compressed kernel image. If you want
161 to make a boot disk (without root filesystem or LILO), insert a floppy
162 in your A: drive, and do a "make bzdisk". It is also possible to do
163 "make install" if you have lilo installed to suit the kernel makefiles,
164 but you may want to check your particular lilo setup first.
165
166 To do the actual install you have to be root, but none of the normal
167 build should require that. Don't take the name of root in vain.
168
169 - In the unlikely event that your system cannot boot bzImage kernels you
170 can still compile your kernel as zImage. However, since zImage support
171 will be removed at some point in the future in favor of bzImage we
172 encourage people having problems with booting bzImage kernels to report
173 these, with detailed hardware configuration information, to the
174 linux-kernel mailing list and to H. Peter Anvin <hpa+linux@zytor.com>.
175
176 - If you configured any of the parts of the kernel as `modules', you
177 will have to do "make modules" followed by "make modules_install".
178 Read Documentation/modules.txt for more information. For example,
179 an explanation of how to use the modules is included there.
180
181 - Keep a backup kernel handy in case something goes wrong. This is
182 especially true for the development releases, since each new release
183 contains new code which has not been debugged. Make sure you keep a
184 backup of the modules corresponding to that kernel, as well. If you
185 are installing a new kernel with the same version number as your
186 working kernel, make a backup of your modules directory before you
187 do a "make modules_install".
188
189 - In order to boot your new kernel, you'll need to copy the kernel
190 image (found in .../linux/arch/i386/boot/bzImage after compilation)
191 to the place where your regular bootable kernel is found.
192
193 For some, this is on a floppy disk, in which case you can copy the
194 kernel bzImage file to /dev/fd0 to make a bootable floppy.
195
196 If you boot Linux from the hard drive, chances are you use LILO which
197 uses the kernel image as specified in the file /etc/lilo.conf. The
198 kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
199 /boot/bzImage. To use the new kernel, save a copy of the old image
200 and copy the new image over the old one. Then, you MUST RERUN LILO
201 to update the loading map!! If you don't, you won't be able to boot
202 the new kernel image.
203
204 Reinstalling LILO is usually a matter of running /sbin/lilo.
205 You may wish to edit /etc/lilo.conf to specify an entry for your
206 old kernel image (say, /vmlinux.old) in case the new one does not
207 work. See the LILO docs for more information.
208
209 After reinstalling LILO, you should be all set. Shutdown the system,
210 reboot, and enjoy!
211
212 If you ever need to change the default root device, video mode,
213 ramdisk size, etc. in the kernel image, use the 'rdev' program (or
214 alternatively the LILO boot options when appropriate). No need to
215 recompile the kernel to change these parameters.
216
217 - Reboot with the new kernel and enjoy.
218
219IF SOMETHING GOES WRONG:
220
221 - If you have problems that seem to be due to kernel bugs, please check
222 the file MAINTAINERS to see if there is a particular person associated
223 with the part of the kernel that you are having trouble with. If there
224 isn't anyone listed there, then the second best thing is to mail
225 them to me (torvalds@transmeta.com), and possibly to any other
226 relevant mailing-list or to the newsgroup. The mailing-lists are
227 useful especially for SCSI and networking problems, as I can't test
228 either of those personally anyway.
229
230 - In all bug-reports, *please* tell what kernel you are talking about,
231 how to duplicate the problem, and what your setup is (use your common
232 sense). If the problem is new, tell me so, and if the problem is
233 old, please try to tell me when you first noticed it.
234
235 - If the bug results in a message like
236
237 unable to handle kernel paging request at address C0000010
238 Oops: 0002
239 EIP: 0010:XXXXXXXX
240 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
241 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
242 ds: xxxx es: xxxx fs: xxxx gs: xxxx
243 Pid: xx, process nr: xx
244 xx xx xx xx xx xx xx xx xx xx
245
246 or similar kernel debugging information on your screen or in your
247 system log, please duplicate it *exactly*. The dump may look
248 incomprehensible to you, but it does contain information that may
249 help debugging the problem. The text above the dump is also
250 important: it tells something about why the kernel dumped code (in
251 the above example it's due to a bad kernel pointer). More information
252 on making sense of the dump is in Documentation/oops-tracing.txt
253
254 - You can use the "ksymoops" program to make sense of the dump. This
255 utility can be downloaded from
256 ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops.
257 Alternately you can do the dump lookup by hand:
258
259 - In debugging dumps like the above, it helps enormously if you can
260 look up what the EIP value means. The hex value as such doesn't help
261 me or anybody else very much: it will depend on your particular
262 kernel setup. What you should do is take the hex value from the EIP
263 line (ignore the "0010:"), and look it up in the kernel namelist to
264 see which kernel function contains the offending address.
265
266 To find out the kernel function name, you'll need to find the system
267 binary associated with the kernel that exhibited the symptom. This is
268 the file 'linux/vmlinux'. To extract the namelist and match it against
269 the EIP from the kernel crash, do:
270
271 nm vmlinux | sort | less
272
273 This will give you a list of kernel addresses sorted in ascending
274 order, from which it is simple to find the function that contains the
275 offending address. Note that the address given by the kernel
276 debugging messages will not necessarily match exactly with the
277 function addresses (in fact, that is very unlikely), so you can't
278 just 'grep' the list: the list will, however, give you the starting
279 point of each kernel function, so by looking for the function that
280 has a starting address lower than the one you are searching for but
281 is followed by a function with a higher address you will find the one
282 you want. In fact, it may be a good idea to include a bit of
283 "context" in your problem report, giving a few lines around the
284 interesting one.
285
286 If you for some reason cannot do the above (you have a pre-compiled
287 kernel image or similar), telling me as much about your setup as
288 possible will help.
289
290 - Alternately, you can use gdb on a running kernel. (read-only; i.e. you
291 cannot change values or set break points.) To do this, first compile the
292 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
293 clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
294
295 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
296 You can now use all the usual gdb commands. The command to look up the
297 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
298 with the EIP value.)
299
300 gdb'ing a non-running kernel currently fails because gdb (wrongly)
301 disregards the starting offset for which the kernel is compiled.
302
303