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1 Linux kernel release 2.1.xx
3 These are the release notes for Linux version 2.1. 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 2.1 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 2.1.xx release.
12 If you need to use a proven and stable Linux kernel, please use 1.0.9,
13 1.2.13, or 2.0.xx. All features which will be in the 2.1.xx releases will
14 be contained in 2.2.xx when the code base has stabilized again.
16 If you decide to use 2.1, 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's in the kernel 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-2.1.XX.tar.gz | tar xfv -
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 2.1.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 your /usr/include/asm, /usr/include/linux, and /usr/include/scsi
100 directories are just symlinks to the kernel sources:
102 cd /usr/include
103 rm -rf asm linux scsi
104 ln -s /usr/src/linux/include/asm-i386 asm
105 ln -s /usr/src/linux/include/linux linux
106 ln -s /usr/src/linux/include/scsi scsi
108 - Make sure you have no stale .o files and dependencies lying around:
110 cd /usr/src/linux
111 make mrproper
113 You should now have the sources correctly installed.
115 SOFTWARE REQUIREMENTS
117 Compiling and running the 2.1.x kernels requires up-to-date
118 versions of various software packages. Consult
119 ./Documentation/Changes for the minimum version numbers required
120 and how to get updates for these packages. Beware that using
121 excessively old versions of these packages can cause indirect
122 errors that are very difficult to track down, so don't assume that
123 you can just update packages when obvious problems arise during
124 build or operation.
126 CONFIGURING the kernel:
128 - Do a "make config" to configure the basic kernel. "make config" needs
129 bash to work: it will search for bash in $BASH, /bin/bash and /bin/sh
130 (in that order), so one of those must be correct for it to work.
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 based configuration tool.
142 "make oldconfig" Default all questions based on the contents of
143 your existing ./.config file.
145 NOTES on "make config":
146 - having unnecessary drivers will make the kernel bigger, and can
147 under some circumstances lead to problems: probing for a
148 nonexistent controller card may confuse your other controllers
149 - compiling the kernel with "Processor type" set higher than 386
150 will result in a kernel that does NOT work on a 386. The
151 kernel will detect this on bootup, and give up.
152 - A kernel with math-emulation compiled in will still use the
153 coprocessor if one is present: the math emulation will just
154 never get used in that case. The kernel will be slightly larger,
155 but will work on different machines regardless of whether they
156 have a math coprocessor or not.
157 - the "kernel hacking" configuration details usually result in a
158 bigger or slower kernel (or both), and can even make the kernel
159 less stable by configuring some routines to actively try to
160 break bad code to find kernel problems (kmalloc()). Thus you
161 should probably answer 'n' to the questions for
162 "development", "experimental", or "debugging" features.
164 - Check the top Makefile for further site-dependent configuration
165 (default SVGA mode etc).
167 - Finally, do a "make dep" to set up all the dependencies correctly.
169 COMPILING the kernel:
171 - Make sure you have gcc-2.7.0 or newer available. It seems older gcc
172 versions can have problems compiling newer versions of Linux. This
173 is mainly because the older compilers can only generate "a.out"-format
174 executables. As of Linux 2.1.0, the kernel must be compiled as an
175 "ELF" binary. If you upgrade your compiler, remember to get the new
176 binutils package too (for as/ld/nm and company).
178 Please note that you can still run a.out user programs with this
179 kernel.
181 - Do a "make zImage" to create a compressed kernel image. If you want
182 to make a boot disk (without root filesystem or LILO), insert a floppy
183 in your A: drive, and do a "make zdisk". It is also possible to do
184 "make zlilo" if you have lilo installed to suit the kernel makefiles,
185 but you may want to check your particular lilo setup first.
187 - If your kernel is too large for "make zImage", use "make bzImage"
188 instead.
190 - If you configured any of the parts of the kernel as `modules', you
191 will have to do "make modules" followed by "make modules_install".
192 Read Documentation/modules.txt for more information. For example,
193 an explanation of how to use the modules is included there.
195 - Keep a backup kernel handy in case something goes wrong. This is
196 especially true for the development releases, since each new release
197 contains new code which has not been debugged. Make sure you keep a
198 backup of the modules corresponding to that kernel, as well. If you
199 are installing a new kernel with the same version number as your
200 working kernel, make a backup of your modules directory before you
201 do a "make modules_install".
203 - In order to boot your new kernel, you'll need to copy the kernel
204 image (found in /usr/src/linux/arch/i386/boot/zImage after compilation)
205 to the place where your regular bootable kernel is found.
207 For some, this is on a floppy disk, in which case you can "cp
208 /usr/src/linux/arch/i386/boot/zImage /dev/fd0" to make a bootable
209 floppy. Please note that you can not boot a kernel by
210 directly dumping it to a 720k double-density 3.5" floppy. In this
211 case, it is highly recommended that you install LILO on your
212 double-density boot floppy or switch to high-density floppies.
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, or /zImage, or /etc/zImage.
217 To use the new kernel, save a copy of the old image and copy the new
218 image over the old one. Then, you MUST RERUN LILO to update the
219 loading map!! If you don't, you won't be able to boot the new kernel
220 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,
228 reboot, and enjoy!
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@transmeta.com), and possibly to any other
244 relevant mailing-list or to the newsgroup. The mailing-lists are
245 useful especially for SCSI and NETworking problems, as I can't test
246 either of those personally anyway.
248 - In all bug-reports, *please* tell what kernel you are talking about,
249 how to duplicate the problem, and what your setup is (use your common
250 sense). If the problem is new, tell me so, and if the problem is
251 old, please try to tell me when you first noticed it.
253 - If the bug results in a message like
255 unable to handle kernel paging request at address C0000010
256 Oops: 0002
257 EIP: 0010:XXXXXXXX
258 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
259 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
260 ds: xxxx es: xxxx fs: xxxx gs: xxxx
261 Pid: xx, process nr: xx
262 xx xx xx xx xx xx xx xx xx xx
264 or similar kernel debugging information on your screen or in your
265 system log, please duplicate it *exactly*. The dump may look
266 incomprehensible to you, but it does contain information that may
267 help debugging the problem. The text above the dump is also
268 important: it tells something about why the kernel dumped code (in
269 the above example it's due to a bad kernel pointer). More information
270 on making sense of the dump is in Documentation/oops-tracing.txt
272 - You can use the "ksymoops" program to make sense of the dump. Find
273 the C++ sources under the scripts/ directory to avoid having to do
274 the dump lookup by hand:
276 - In debugging dumps like the above, it helps enormously if you can
277 look up what the EIP value means. The hex value as such doesn't help
278 me or anybody else very much: it will depend on your particular
279 kernel setup. What you should do is take the hex value from the EIP
280 line (ignore the "0010:"), and look it up in the kernel namelist to
281 see which kernel function contains the offending address.
283 To find out the kernel function name, you'll need to find the system
284 binary associated with the kernel that exhibited the symptom. This is
285 the file 'linux/vmlinux'. To extract the namelist and match it against
286 the EIP from the kernel crash, do:
288 nm vmlinux | sort | less
290 This will give you a list of kernel addresses sorted in ascending
291 order, from which it is simple to find the function that contains the
292 offending address. Note that the address given by the kernel
293 debugging messages will not necessarily match exactly with the
294 function addresses (in fact, that is very unlikely), so you can't
295 just 'grep' the list: the list will, however, give you the starting
296 point of each kernel function, so by looking for the function that
297 has a starting address lower than the one you are searching for but
298 is followed by a function with a higher address you will find the one
299 you want. In fact, it may be a good idea to include a bit of
300 "context" in your problem report, giving a few lines around the
301 interesting one.
303 If you for some reason cannot do the above (you have a pre-compiled
304 kernel image or similar), telling me as much about your setup as
305 possible will help.
307 - Alternately, you can use gdb on a running kernel. (read-only; i.e. you
308 cannot change values or set break points.) To do this, first compile the
309 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
310 clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
312 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
313 You can now use all the usual gdb commands. The command to look up the
314 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
315 with the EIP value.)
317 gdb'ing a non-running kernel currently fails because gdb (wrongly)
318 disregards the starting offset for which the kernel is compiled.