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1 Linux kernel release 2.6.xx <http://kernel.org>
2
3 These are the release notes for Linux version 2.6. 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.
6
7 WHAT IS LINUX?
8
9 Linux is a clone of the operating system Unix, written from scratch by
10 Linus Torvalds with assistance from a loosely-knit team of hackers across
11 the Net. It aims towards POSIX and Single UNIX Specification compliance.
12
13 It has all the features you would expect in a modern fully-fledged Unix,
14 including true multitasking, virtual memory, shared libraries, demand
15 loading, shared copy-on-write executables, proper memory management,
16 and multistack networking including IPv4 and IPv6.
17
18 It is distributed under the GNU General Public License - see the
19 accompanying COPYING file for more details.
20
21 ON WHAT HARDWARE DOES IT RUN?
22
23 Although originally developed first for 32-bit x86-based PCs (386 or higher),
24 today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and
25 UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH,
26 IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS,
27 and Renesas M32R architectures.
28
29 Linux is easily portable to most general-purpose 32- or 64-bit architectures
30 as long as they have a paged memory management unit (PMMU) and a port of the
31 GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has
32 also been ported to a number of architectures without a PMMU, although
33 functionality is then obviously somewhat limited.
34
35 DOCUMENTATION:
36
37 - There is a lot of documentation available both in electronic form on
38 the Internet and in books, both Linux-specific and pertaining to
39 general UNIX questions. I'd recommend looking into the documentation
40 subdirectories on any Linux FTP site for the LDP (Linux Documentation
41 Project) books. This README is not meant to be documentation on the
42 system: there are much better sources available.
43
44 - There are various README files in the Documentation/ subdirectory:
45 these typically contain kernel-specific installation notes for some
46 drivers for example. See Documentation/00-INDEX for a list of what
47 is contained in each file. Please read the Changes file, as it
48 contains information about the problems, which may result by upgrading
49 your kernel.
50
51 - The Documentation/DocBook/ subdirectory contains several guides for
52 kernel developers and users. These guides can be rendered in a
53 number of formats: PostScript (.ps), PDF, and HTML, among others.
54 After installation, "make psdocs", "make pdfdocs", or "make htmldocs"
55 will render the documentation in the requested format.
56
57 INSTALLING the kernel:
58
59 - If you install the full sources, put the kernel tarball in a
60 directory where you have permissions (eg. your home directory) and
61 unpack it:
62
63 gzip -cd linux-2.6.XX.tar.gz | tar xvf -
64
65 or
66 bzip2 -dc linux-2.6.XX.tar.bz2 | tar xvf -
67
68
69 Replace "XX" with the version number of the latest kernel.
70
71 Do NOT use the /usr/src/linux area! This area has a (usually
72 incomplete) set of kernel headers that are used by the library header
73 files. They should match the library, and not get messed up by
74 whatever the kernel-du-jour happens to be.
75
76 - You can also upgrade between 2.6.xx releases by patching. Patches are
77 distributed in the traditional gzip and the newer bzip2 format. To
78 install by patching, get all the newer patch files, enter the
79 top level directory of the kernel source (linux-2.6.xx) and execute:
80
81 gzip -cd ../patch-2.6.xx.gz | patch -p1
82
83 or
84 bzip2 -dc ../patch-2.6.xx.bz2 | patch -p1
85
86 (repeat xx for all versions bigger than the version of your current
87 source tree, _in_order_) and you should be ok. You may want to remove
88 the backup files (xxx~ or xxx.orig), and make sure that there are no
89 failed patches (xxx# or xxx.rej). If there are, either you or me has
90 made a mistake.
91
92 Unlike patches for the 2.6.x kernels, patches for the 2.6.x.y kernels
93 (also known as the -stable kernels) are not incremental but instead apply
94 directly to the base 2.6.x kernel. Please read
95 Documentation/applying-patches.txt for more information.
96
97 Alternatively, the script patch-kernel can be used to automate this
98 process. It determines the current kernel version and applies any
99 patches found.
100
101 linux/scripts/patch-kernel linux
102
103 The first argument in the command above is the location of the
104 kernel source. Patches are applied from the current directory, but
105 an alternative directory can be specified as the second argument.
106
107 - If you are upgrading between releases using the stable series patches
108 (for example, patch-2.6.xx.y), note that these "dot-releases" are
109 not incremental and must be applied to the 2.6.xx base tree. For
110 example, if your base kernel is 2.6.12 and you want to apply the
111 2.6.12.3 patch, you do not and indeed must not first apply the
112 2.6.12.1 and 2.6.12.2 patches. Similarly, if you are running kernel
113 version 2.6.12.2 and want to jump to 2.6.12.3, you must first
114 reverse the 2.6.12.2 patch (that is, patch -R) _before_ applying
115 the 2.6.12.3 patch.
116
117 - Make sure you have no stale .o files and dependencies lying around:
118
119 cd linux
120 make mrproper
121
122 You should now have the sources correctly installed.
123
124 SOFTWARE REQUIREMENTS
125
126 Compiling and running the 2.6.xx kernels requires up-to-date
127 versions of various software packages. Consult
128 Documentation/Changes for the minimum version numbers required
129 and how to get updates for these packages. Beware that using
130 excessively old versions of these packages can cause indirect
131 errors that are very difficult to track down, so don't assume that
132 you can just update packages when obvious problems arise during
133 build or operation.
134
135 BUILD directory for the kernel:
136
137 When compiling the kernel all output files will per default be
138 stored together with the kernel source code.
139 Using the option "make O=output/dir" allow you to specify an alternate
140 place for the output files (including .config).
141 Example:
142 kernel source code: /usr/src/linux-2.6.N
143 build directory: /home/name/build/kernel
144
145 To configure and build the kernel use:
146 cd /usr/src/linux-2.6.N
147 make O=/home/name/build/kernel menuconfig
148 make O=/home/name/build/kernel
149 sudo make O=/home/name/build/kernel modules_install install
150
151 Please note: If the 'O=output/dir' option is used then it must be
152 used for all invocations of make.
153
154 CONFIGURING the kernel:
155
156 Do not skip this step even if you are only upgrading one minor
157 version. New configuration options are added in each release, and
158 odd problems will turn up if the configuration files are not set up
159 as expected. If you want to carry your existing configuration to a
160 new version with minimal work, use "make oldconfig", which will
161 only ask you for the answers to new questions.
162
163 - Alternate configuration commands are:
164 "make menuconfig" Text based color menus, radiolists & dialogs.
165 "make xconfig" X windows (Qt) based configuration tool.
166 "make gconfig" X windows (Gtk) based configuration tool.
167 "make oldconfig" Default all questions based on the contents of
168 your existing ./.config file.
169 "make silentoldconfig"
170 Like above, but avoids cluttering the screen
171 with questions already answered.
172
173 NOTES on "make config":
174 - having unnecessary drivers will make the kernel bigger, and can
175 under some circumstances lead to problems: probing for a
176 nonexistent controller card may confuse your other controllers
177 - compiling the kernel with "Processor type" set higher than 386
178 will result in a kernel that does NOT work on a 386. The
179 kernel will detect this on bootup, and give up.
180 - A kernel with math-emulation compiled in will still use the
181 coprocessor if one is present: the math emulation will just
182 never get used in that case. The kernel will be slightly larger,
183 but will work on different machines regardless of whether they
184 have a math coprocessor or not.
185 - the "kernel hacking" configuration details usually result in a
186 bigger or slower kernel (or both), and can even make the kernel
187 less stable by configuring some routines to actively try to
188 break bad code to find kernel problems (kmalloc()). Thus you
189 should probably answer 'n' to the questions for
190 "development", "experimental", or "debugging" features.
191
192 COMPILING the kernel:
193
194 - Make sure you have at least gcc 3.2 available.
195 For more information, refer to Documentation/Changes.
196
197 Please note that you can still run a.out user programs with this kernel.
198
199 - Do a "make" to create a compressed kernel image. It is also
200 possible to do "make install" if you have lilo installed to suit the
201 kernel makefiles, but you may want to check your particular lilo setup first.
202
203 To do the actual install you have to be root, but none of the normal
204 build should require that. Don't take the name of root in vain.
205
206 - If you configured any of the parts of the kernel as `modules', you
207 will also have to do "make modules_install".
208
209 - Keep a backup kernel handy in case something goes wrong. This is
210 especially true for the development releases, since each new release
211 contains new code which has not been debugged. Make sure you keep a
212 backup of the modules corresponding to that kernel, as well. If you
213 are installing a new kernel with the same version number as your
214 working kernel, make a backup of your modules directory before you
215 do a "make modules_install".
216 Alternatively, before compiling, use the kernel config option
217 "LOCALVERSION" to append a unique suffix to the regular kernel version.
218 LOCALVERSION can be set in the "General Setup" menu.
219
220 - In order to boot your new kernel, you'll need to copy the kernel
221 image (e.g. .../linux/arch/i386/boot/bzImage after compilation)
222 to the place where your regular bootable kernel is found.
223
224 - Booting a kernel directly from a floppy without the assistance of a
225 bootloader such as LILO, is no longer supported.
226
227 If you boot Linux from the hard drive, chances are you use LILO which
228 uses the kernel image as specified in the file /etc/lilo.conf. The
229 kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
230 /boot/bzImage. To use the new kernel, save a copy of the old image
231 and copy the new image over the old one. Then, you MUST RERUN LILO
232 to update the loading map!! If you don't, you won't be able to boot
233 the new kernel image.
234
235 Reinstalling LILO is usually a matter of running /sbin/lilo.
236 You may wish to edit /etc/lilo.conf to specify an entry for your
237 old kernel image (say, /vmlinux.old) in case the new one does not
238 work. See the LILO docs for more information.
239
240 After reinstalling LILO, you should be all set. Shutdown the system,
241 reboot, and enjoy!
242
243 If you ever need to change the default root device, video mode,
244 ramdisk size, etc. in the kernel image, use the 'rdev' program (or
245 alternatively the LILO boot options when appropriate). No need to
246 recompile the kernel to change these parameters.
247
248 - Reboot with the new kernel and enjoy.
249
250 IF SOMETHING GOES WRONG:
251
252 - If you have problems that seem to be due to kernel bugs, please check
253 the file MAINTAINERS to see if there is a particular person associated
254 with the part of the kernel that you are having trouble with. If there
255 isn't anyone listed there, then the second best thing is to mail
256 them to me (torvalds@osdl.org), and possibly to any other relevant
257 mailing-list or to the newsgroup.
258
259 - In all bug-reports, *please* tell what kernel you are talking about,
260 how to duplicate the problem, and what your setup is (use your common
261 sense). If the problem is new, tell me so, and if the problem is
262 old, please try to tell me when you first noticed it.
263
264 - If the bug results in a message like
265
266 unable to handle kernel paging request at address C0000010
267 Oops: 0002
268 EIP: 0010:XXXXXXXX
269 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
270 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
271 ds: xxxx es: xxxx fs: xxxx gs: xxxx
272 Pid: xx, process nr: xx
273 xx xx xx xx xx xx xx xx xx xx
274
275 or similar kernel debugging information on your screen or in your
276 system log, please duplicate it *exactly*. The dump may look
277 incomprehensible to you, but it does contain information that may
278 help debugging the problem. The text above the dump is also
279 important: it tells something about why the kernel dumped code (in
280 the above example it's due to a bad kernel pointer). More information
281 on making sense of the dump is in Documentation/oops-tracing.txt
282
283 - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump
284 as is, otherwise you will have to use the "ksymoops" program to make
285 sense of the dump. This utility can be downloaded from
286 ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops.
287 Alternately you can do the dump lookup by hand:
288
289 - In debugging dumps like the above, it helps enormously if you can
290 look up what the EIP value means. The hex value as such doesn't help
291 me or anybody else very much: it will depend on your particular
292 kernel setup. What you should do is take the hex value from the EIP
293 line (ignore the "0010:"), and look it up in the kernel namelist to
294 see which kernel function contains the offending address.
295
296 To find out the kernel function name, you'll need to find the system
297 binary associated with the kernel that exhibited the symptom. This is
298 the file 'linux/vmlinux'. To extract the namelist and match it against
299 the EIP from the kernel crash, do:
300
301 nm vmlinux | sort | less
302
303 This will give you a list of kernel addresses sorted in ascending
304 order, from which it is simple to find the function that contains the
305 offending address. Note that the address given by the kernel
306 debugging messages will not necessarily match exactly with the
307 function addresses (in fact, that is very unlikely), so you can't
308 just 'grep' the list: the list will, however, give you the starting
309 point of each kernel function, so by looking for the function that
310 has a starting address lower than the one you are searching for but
311 is followed by a function with a higher address you will find the one
312 you want. In fact, it may be a good idea to include a bit of
313 "context" in your problem report, giving a few lines around the
314 interesting one.
315
316 If you for some reason cannot do the above (you have a pre-compiled
317 kernel image or similar), telling me as much about your setup as
318 possible will help.
319
320 - Alternately, you can use gdb on a running kernel. (read-only; i.e. you
321 cannot change values or set break points.) To do this, first compile the
322 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
323 clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
324
325 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
326 You can now use all the usual gdb commands. The command to look up the
327 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
328 with the EIP value.)
329
330 gdb'ing a non-running kernel currently fails because gdb (wrongly)
331 disregards the starting offset for which the kernel is compiled.
332