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2 Linux kernel release 2.1.xx
4 These are the release notes for linux version 2.1. Read them carefully,
5 as they tell you what this is all about, explain how to install the
6 kernel, and what to do if something goes wrong.
8 Linux version 2.1 is a DEVELOPMENT kernel, and not intended for general
9 public use. Different releases may have various and sometimes severe
10 bugs. It is *strongly* recommended that you back up the previous kernel
11 before installing any new 2.1.xx release.
13 If you need to use a proven and stable Linux kernel, please use 1.0.9,
14 1.2.13, or 2.0.xx. All features which will be in the 2.1.xx releases will
15 be contained in 2.2.xx when the code base has stabilized again.
17 If you decide to use 2.1, it is recommended that you join the kernel mailing
18 list. To do this, e-mail majordomo@vger.rutgers.edu, and put in the body
19 of the message "subscribe linux-kernel" or "subscribe linux-kernel-digest"
20 for a daily digest of the mailing list (it is a high-traffic list.)
22 However, please make sure you don't ask questions which are already answered
23 in various files in the Documentation directory. See DOCUMENTATION below.
25 WHAT IS LINUX?
27 Linux is a Unix clone written from scratch by Linus Torvalds with
28 assistance from a loosely-knit team of hackers across the Net.
29 It aims towards POSIX compliance.
31 It has all the features you would expect in a modern fully-fledged
32 Unix, including true multitasking, virtual memory, shared libraries,
33 demand loading, shared copy-on-write executables, proper memory
34 management and TCP/IP networking.
36 It is distributed under the GNU General Public License - see the
37 accompanying COPYING file for more details.
39 ON WHAT HARDWARE DOES IT RUN?
41 Linux was first developed for 386/486-based PCs. These days it also
42 runs on DEC Alphas, SUN Sparcs, M68000 machines (like Atari and Amiga),
43 MIPS and PowerPC.
45 DOCUMENTATION:
47 - There is a lot of documentation available both in electronic form on
48 the internet and in books, both Linux-specific and pertaining to
49 general UNIX questions. I'd recommend looking into the documentation
50 subdirectories on any Linux ftp site for the LDP (Linux Documentation
51 Project) books. This README is not meant to be documentation on the
52 system: there are much better sources available.
54 - There are various readme's in the kernel Documentation/ subdirectory:
55 these typically contain kernel-specific installation notes for some
56 drivers for example. See ./Documentation/00-INDEX for a list of what
57 is contained in each file. Please read the Changes file, as it
58 contains information about the problems, which may result by upgrading
59 your kernel.
61 INSTALLING the kernel:
63 - If you install the full sources, do a
65 cd /usr/src
66 gzip -cd linux-2.1.XX.tar.gz | tar xfv -
68 to get it all put in place. Replace "XX" with the version number of the
69 latest kernel.
71 - You can also upgrade between 2.1.xx releases by patching. To install
72 by patching, get all the newer patch files and do
74 cd /usr/src
75 gzip -cd patchXX.gz | patch -p0
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
81 made a mistake.
83 Alternatively, the script patch-kernel can be used to automate this
84 process. It determines the current kernel version and applies any
85 patches found.
87 cd /usr/src
88 linux/scripts/patch-kernel
90 The default directory for the kernel source is /usr/src/linux, but
91 can be specified as the first argument. Patches are applied from
92 the current directory, but an alternative directory can be specified
93 as the second argument.
95 - Make sure your /usr/include/asm, /usr/include/linux, and /usr/include/scsi
96 directories are just symlinks to the kernel sources:
98 cd /usr/include
99 rm -rf asm linux scsi
100 ln -s /usr/src/linux/include/asm-i386 asm
101 ln -s /usr/src/linux/include/linux linux
102 ln -s /usr/src/linux/include/scsi scsi
104 - Make sure you have no stale .o files and dependencies lying around:
106 cd /usr/src/linux
107 make mrproper
109 You should now have the sources correctly installed.
111 SOFTWARE REQUIREMENTS
113 Compiling and running the 2.1.x kernels requires up-to-date
114 versions of various software packages. Consult
115 ./Documentation/Changes for the minimum version numbers required
116 and how to get updates for these packages. Beware that using
117 excessively old versions of these packages can cause indirect
118 errors that are very difficult to track down, so don't assume that
119 you can just update packages when obvious problems arise during
120 build or operation.
122 CONFIGURING the kernel:
124 - Do a "make config" to configure the basic kernel. "make config"
125 needs bash to work: it will search for bash in $BASH, /bin/bash and
126 /bin/sh (in that order), so hopefully one of those is correct.
128 (Do not skip this step even if you are only upgrading one minor
129 version. New configuration options are added in each release, and
130 odd problems will turn up if the configuration files are not set up
131 as expected. If you want to carry your existing configuration to a
132 new version with minimal work, use "make oldconfig", which will
133 only ask you for the answers to new questions.)
135 - Alternate configuration commands are:
136 "make menuconfig" Text based color menus, radiolists & dialogs.
137 "make xconfig" X windows based configuration tool.
138 "make oldconfig" Default all questions based on the contents of
139 your existing ./.config file.
141 NOTES on "make config":
142 - having unnecessary drivers will make the kernel bigger, and can
143 under some circumstances lead to problems: probing for a
144 nonexistent controller card may confuse your other controllers
145 - compiling the kernel with "Processor type" set higher than 386
146 will result in a kernel that does NOT work on a 386. The
147 kernel will detect this on bootup, and give up.
148 - A kernel with math-emulation compiled in will still use the
149 coprocessor if one is present: the math emulation will just
150 never get used in that case. The kernel will be slightly larger,
151 but will work on different machines regardless of whether they
152 have a math coprocessor or not.
153 - the "kernel hacking" configuration details usually result in a
154 bigger or slower kernel (or both), and can even make the kernel
155 less stable by configuring some routines to actively try to
156 break bad code to find kernel problems (kmalloc()). Thus you
157 should probably answer 'n' to the questions for
158 "development", "experimental", or "debugging" features.
160 - Check the top Makefile for further site-dependent configuration
161 (default SVGA mode etc).
163 - Finally, do a "make dep" to set up all the dependencies correctly.
165 COMPILING the kernel:
167 - Make sure you have gcc-2.7.0 or newer available. It seems older gcc
168 versions can have problems compiling newer versions of linux. This
169 is mainly because the older compilers can only generate "a.out"-format
170 executables. As of Linux 2.1.0, the kernel must be compiled as an
171 "ELF" binary. If you upgrade your compiler, remember to get the new
172 binutils package too (for as/ld/nm and company).
174 Please note that you can still run a.out user programs with this
175 kernel.
177 - Do a "make zImage" to create a compressed kernel image. If you want
178 to make a bootdisk (without root filesystem or lilo), insert a floppy
179 in your A: drive, and do a "make zdisk". It is also possible to do
180 "make zlilo" if you have lilo installed to suit the kernel makefiles,
181 but you may want to check your particular lilo setup first.
183 - If your kernel is too large for "make zImage", use "make bzImage"
184 instead.
186 - If you configured any of the parts of the kernel as `modules', you
187 will have to do "make modules" followed by "make modules_install".
188 Read Documentation/modules.txt for more information. For example,
189 an explanation of how to use the modules is included there.
191 - Keep a backup kernel handy in case something goes wrong. This is
192 especially true for the development releases, since each new release
193 contains new code which has not been debugged.
195 - In order to boot your new kernel, you'll need to copy the kernel
196 image (found in /usr/src/linux/arch/i386/boot/zImage after compilation)
197 to the place where your regular bootable kernel is found.
199 For some, this is on a floppy disk, in which case you can "cp
200 /usr/src/linux/arch/i386/boot/zImage /dev/fd0" to make a bootable
201 floppy. Please note that you can not boot a kernel by
202 directly dumping it to a 720k double-density 3.5" floppy. In this
203 case, it is highly recommended that you install LILO on your
204 double-density boot floppy or switch to high-density floppies.
206 If you boot Linux from the hard drive, chances are you use LILO which
207 uses the kernel image as specified in the file /etc/lilo.conf. The
208 kernel image file is usually /vmlinuz, or /zImage, or /etc/zImage.
209 To use the new kernel, copy the new image over the old one (save a
210 backup of the original!). Then, you MUST RERUN LILO to update the
211 loading map!! If you don't, you won't be able to boot the new kernel
212 image.
214 Reinstalling LILO is usually a matter of running /sbin/lilo.
215 You may wish to edit /etc/lilo.conf to specify an entry for your
216 old kernel image (say, /vmlinux.old) in case the new one does not
217 work. See the LILO docs for more information.
219 After reinstalling LILO, you should be all set. Shutdown the system,
220 reboot, and enjoy!
222 If you ever need to change the default root device, video mode,
223 ramdisk size, etc. in the kernel image, use the 'rdev' program (or
224 alternatively the LILO boot options when appropriate). No need to
225 recompile the kernel to change these parameters.
227 - Reboot with the new kernel and enjoy.
229 IF SOMETHING GOES WRONG:
231 - If you have problems that seem to be due to kernel bugs, please check
232 the file MAINTAINERS to see if there is a particular person associated
233 with the part of the kernel that you are having trouble with. If there
234 isn't anyone listed there, then the second best thing is to mail
235 them to me (Linus.Torvalds@Helsinki.FI), and possibly to any other
236 relevant mailing-list or to the newsgroup. The mailing-lists are
237 useful especially for SCSI and NETworking problems, as I can't test
238 either of those personally anyway.
240 - In all bug-reports, *please* tell what kernel you are talking about,
241 how to duplicate the problem, and what your setup is (use your common
242 sense). If the problem is new, tell me so, and if the problem is
243 old, please try to tell me when you first noticed it.
245 - If the bug results in a message like
247 unable to handle kernel paging request at address C0000010
248 Oops: 0002
249 EIP: 0010:XXXXXXXX
250 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
251 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
252 ds: xxxx es: xxxx fs: xxxx gs: xxxx
253 Pid: xx, process nr: xx
254 xx xx xx xx xx xx xx xx xx xx
256 or similar kernel debugging information on your screen or in your
257 system log, please duplicate it *exactly*. The dump may look
258 incomprehensible to you, but it does contain information that may
259 help debugging the problem. The text above the dump is also
260 important: it tells something about why the kernel dumped code (in
261 the above example it's due to a bad kernel pointer). More information
262 on making sense of the dump is in Documentation/oops-tracing.txt
264 - You can use the "ksymoops" program to make sense of the dump. Find
265 the C++ sources under the scripts/ directory to avoid having to do
266 the dump lookup by hand:
268 - In debugging dumps like the above, it helps enormously if you can
269 look up what the EIP value means. The hex value as such doesn't help
270 me or anybody else very much: it will depend on your particular
271 kernel setup. What you should do is take the hex value from the EIP
272 line (ignore the "0010:"), and look it up in the kernel namelist to
273 see which kernel function contains the offending address.
275 To find out the kernel function name, you'll need to find the system
276 binary associated with the kernel that exhibited the symptom. This is
277 the file 'linux/vmlinux'. To extract the namelist and match it against
278 the EIP from the kernel crash, do:
280 nm vmlinux | sort | less
282 This will give you a list of kernel addresses sorted in ascending
283 order, from which it is simple to find the function that contains the
284 offending address. Note that the address given by the kernel
285 debugging messages will not necessarily match exactly with the
286 function addresses (in fact, that is very unlikely), so you can't
287 just 'grep' the list: the list will, however, give you the starting
288 point of each kernel function, so by looking for the function that
289 has a starting address lower than the one you are searching for but
290 is followed by a function with a higher address you will find the one
291 you want. In fact, it may be a good idea to include a bit of
292 "context" in your problem report, giving a few lines around the
293 interesting one.
295 If you for some reason cannot do the above (you have a pre-compiled
296 kernel image or similar), telling me as much about your setup as
297 possible will help.
299 - Alternately, you can use gdb on a running kernel. (read-only; i.e. you
300 cannot change values or set break points.) To do this, first compile the
301 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
302 clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
304 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
305 You can now use all the usual gdb commands. The command to look up the
306 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
307 with the EIP value.)
309 gdb'ing a non-running kernel currently fails because gdb (wrongly)
310 disregards the starting offset for which the kernel is compiled.