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4f4e2dc3 | 1 | Linux kernel release 2.6.xx <http://kernel.org> |
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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 | ||
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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. | |
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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. | |
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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 | ||
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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. | |
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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 | ||
b39f72fe H |
65 | or |
66 | bzip2 -dc linux-2.6.XX.tar.bz2 | tar xvf - | |
67 | ||
68 | ||
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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 new 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 | ||
6ad44229 JJ |
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 | ||
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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 | ||
896e5518 KW |
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 | ||
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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. | |
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169 | "make silentoldconfig" |
170 | Like above, but avoids cluttering the screen | |
e3fc4cc1 | 171 | with questions already answered. |
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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 | ||
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192 | COMPILING the kernel: |
193 | ||
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194 | - Make sure you have at least gcc 3.2 available. |
195 | For more information, refer to Documentation/Changes. | |
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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". | |
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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. | |
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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 |