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 top level directory of the kernel source (linux-2.4.xx) and execute:
68
69 gzip -cd ../patch-2.4.xx.gz | patch -p1
70
71 or
72 bzip2 -dc ../patch-2.4.xx.bz2 | patch -p1
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 gcc 4 is *not* supported.
156 Also remember to upgrade your binutils package (for as/ld/nm and company)
157 if necessary. For more information, refer to ./Documentation/Changes.
158
159 Please note that you can still run a.out user programs with this kernel.
160
161 - Do a "make bzImage" to create a compressed kernel image. If you want
162 to make a boot disk (without root filesystem or LILO), insert a floppy
163 in your A: drive, and do a "make bzdisk". It is also possible to do
164 "make install" if you have lilo installed to suit the kernel makefiles,
165 but you may want to check your particular lilo setup first.
166
167 To do the actual install you have to be root, but none of the normal
168 build should require that. Don't take the name of root in vain.
169
170 - In the unlikely event that your system cannot boot bzImage kernels you
171 can still compile your kernel as zImage. However, since zImage support
172 will be removed at some point in the future in favor of bzImage we
173 encourage people having problems with booting bzImage kernels to report
174 these, with detailed hardware configuration information, to the
175 linux-kernel mailing list and to H. Peter Anvin <hpa+linux@zytor.com>.
176
177 - If you configured any of the parts of the kernel as `modules', you
178 will have to do "make modules" followed by "make modules_install".
179 Read Documentation/modules.txt for more information. For example,
180 an explanation of how to use the modules is included there.
181
182 - Keep a backup kernel handy in case something goes wrong. This is
183 especially true for the development releases, since each new release
184 contains new code which has not been debugged. Make sure you keep a
185 backup of the modules corresponding to that kernel, as well. If you
186 are installing a new kernel with the same version number as your
187 working kernel, make a backup of your modules directory before you
188 do a "make modules_install".
189
190 - In order to boot your new kernel, you'll need to copy the kernel
191 image (found in .../linux/arch/i386/boot/bzImage after compilation)
192 to the place where your regular bootable kernel is found.
193
194 For some, this is on a floppy disk, in which case you can copy the
195 kernel bzImage file to /dev/fd0 to make a bootable floppy.
196
197 If you boot Linux from the hard drive, chances are you use LILO which
198 uses the kernel image as specified in the file /etc/lilo.conf. The
199 kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
200 /boot/bzImage. To use the new kernel, save a copy of the old image
201 and copy the new image over the old one. Then, you MUST RERUN LILO
202 to update the loading map!! If you don't, you won't be able to boot
203 the new kernel image.
204
205 Reinstalling LILO is usually a matter of running /sbin/lilo.
206 You may wish to edit /etc/lilo.conf to specify an entry for your
207 old kernel image (say, /vmlinux.old) in case the new one does not
208 work. See the LILO docs for more information.
209
210 After reinstalling LILO, you should be all set. Shutdown the system,
211 reboot, and enjoy!
212
213 If you ever need to change the default root device, video mode,
214 ramdisk size, etc. in the kernel image, use the 'rdev' program (or
215 alternatively the LILO boot options when appropriate). No need to
216 recompile the kernel to change these parameters.
217
218 - Reboot with the new kernel and enjoy.
219
220IF SOMETHING GOES WRONG:
221
222 - If you have problems that seem to be due to kernel bugs, please check
223 the file MAINTAINERS to see if there is a particular person associated
224 with the part of the kernel that you are having trouble with. If there
225 isn't anyone listed there, then the second best thing is to mail
226 them to me (torvalds@transmeta.com), and possibly to any other
227 relevant mailing-list or to the newsgroup. The mailing-lists are
228 useful especially for SCSI and networking problems, as I can't test
229 either of those personally anyway.
230
231 - In all bug-reports, *please* tell what kernel you are talking about,
232 how to duplicate the problem, and what your setup is (use your common
233 sense). If the problem is new, tell me so, and if the problem is
234 old, please try to tell me when you first noticed it.
235
236 - If the bug results in a message like
237
238 unable to handle kernel paging request at address C0000010
239 Oops: 0002
240 EIP: 0010:XXXXXXXX
241 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
242 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
243 ds: xxxx es: xxxx fs: xxxx gs: xxxx
244 Pid: xx, process nr: xx
245 xx xx xx xx xx xx xx xx xx xx
246
247 or similar kernel debugging information on your screen or in your
248 system log, please duplicate it *exactly*. The dump may look
249 incomprehensible to you, but it does contain information that may
250 help debugging the problem. The text above the dump is also
251 important: it tells something about why the kernel dumped code (in
252 the above example it's due to a bad kernel pointer). More information
253 on making sense of the dump is in Documentation/oops-tracing.txt
254
255 - You can use the "ksymoops" program to make sense of the dump. This
256 utility can be downloaded from
257 ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops.
258 Alternately you can do the dump lookup by hand:
259
260 - In debugging dumps like the above, it helps enormously if you can
261 look up what the EIP value means. The hex value as such doesn't help
262 me or anybody else very much: it will depend on your particular
263 kernel setup. What you should do is take the hex value from the EIP
264 line (ignore the "0010:"), and look it up in the kernel namelist to
265 see which kernel function contains the offending address.
266
267 To find out the kernel function name, you'll need to find the system
268 binary associated with the kernel that exhibited the symptom. This is
269 the file 'linux/vmlinux'. To extract the namelist and match it against
270 the EIP from the kernel crash, do:
271
272 nm vmlinux | sort | less
273
274 This will give you a list of kernel addresses sorted in ascending
275 order, from which it is simple to find the function that contains the
276 offending address. Note that the address given by the kernel
277 debugging messages will not necessarily match exactly with the
278 function addresses (in fact, that is very unlikely), so you can't
279 just 'grep' the list: the list will, however, give you the starting
280 point of each kernel function, so by looking for the function that
281 has a starting address lower than the one you are searching for but
282 is followed by a function with a higher address you will find the one
283 you want. In fact, it may be a good idea to include a bit of
284 "context" in your problem report, giving a few lines around the
285 interesting one.
286
287 If you for some reason cannot do the above (you have a pre-compiled
288 kernel image or similar), telling me as much about your setup as
289 possible will help.
290
291 - Alternately, you can use gdb on a running kernel. (read-only; i.e. you
292 cannot change values or set break points.) To do this, first compile the
293 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
294 clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
295
296 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
297 You can now use all the usual gdb commands. The command to look up the
298 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
299 with the EIP value.)
300
301 gdb'ing a non-running kernel currently fails because gdb (wrongly)
302 disregards the starting offset for which the kernel is compiled.
303
304