]>
Commit | Line | Data |
---|---|---|
1 | Linux kernel release 3.x <http://kernel.org/> | |
2 | ||
3 | These are the release notes for Linux version 3. 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, Cell, | |
26 | IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS, | |
27 | Xtensa, Tilera TILE, AVR32 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 | Linux has also been ported to itself. You can now run the kernel as a | |
35 | userspace application - this is called UserMode Linux (UML). | |
36 | ||
37 | DOCUMENTATION: | |
38 | ||
39 | - There is a lot of documentation available both in electronic form on | |
40 | the Internet and in books, both Linux-specific and pertaining to | |
41 | general UNIX questions. I'd recommend looking into the documentation | |
42 | subdirectories on any Linux FTP site for the LDP (Linux Documentation | |
43 | Project) books. This README is not meant to be documentation on the | |
44 | system: there are much better sources available. | |
45 | ||
46 | - There are various README files in the Documentation/ subdirectory: | |
47 | these typically contain kernel-specific installation notes for some | |
48 | drivers for example. See Documentation/00-INDEX for a list of what | |
49 | is contained in each file. Please read the Changes file, as it | |
50 | contains information about the problems, which may result by upgrading | |
51 | your kernel. | |
52 | ||
53 | - The Documentation/DocBook/ subdirectory contains several guides for | |
54 | kernel developers and users. These guides can be rendered in a | |
55 | number of formats: PostScript (.ps), PDF, HTML, & man-pages, among others. | |
56 | After installation, "make psdocs", "make pdfdocs", "make htmldocs", | |
57 | or "make mandocs" will render the documentation in the requested format. | |
58 | ||
59 | INSTALLING the kernel source: | |
60 | ||
61 | - If you install the full sources, put the kernel tarball in a | |
62 | directory where you have permissions (eg. your home directory) and | |
63 | unpack it: | |
64 | ||
65 | gzip -cd linux-3.X.tar.gz | tar xvf - | |
66 | ||
67 | or | |
68 | ||
69 | bzip2 -dc linux-3.X.tar.bz2 | tar xvf - | |
70 | ||
71 | Replace "X" with the version number of the latest kernel. | |
72 | ||
73 | Do NOT use the /usr/src/linux area! This area has a (usually | |
74 | incomplete) set of kernel headers that are used by the library header | |
75 | files. They should match the library, and not get messed up by | |
76 | whatever the kernel-du-jour happens to be. | |
77 | ||
78 | - You can also upgrade between 3.x releases by patching. Patches are | |
79 | distributed in the traditional gzip and the newer bzip2 format. To | |
80 | install by patching, get all the newer patch files, enter the | |
81 | top level directory of the kernel source (linux-3.X) and execute: | |
82 | ||
83 | gzip -cd ../patch-3.x.gz | patch -p1 | |
84 | ||
85 | or | |
86 | ||
87 | bzip2 -dc ../patch-3.x.bz2 | patch -p1 | |
88 | ||
89 | Replace "x" for all versions bigger than the version "X" of your current | |
90 | source tree, _in_order_, and you should be ok. You may want to remove | |
91 | the backup files (some-file-name~ or some-file-name.orig), and make sure | |
92 | that there are no failed patches (some-file-name# or some-file-name.rej). | |
93 | If there are, either you or I have made a mistake. | |
94 | ||
95 | Unlike patches for the 3.x kernels, patches for the 3.x.y kernels | |
96 | (also known as the -stable kernels) are not incremental but instead apply | |
97 | directly to the base 3.x kernel. For example, if your base kernel is 3.0 | |
98 | and you want to apply the 3.0.3 patch, you must not first apply the 3.0.1 | |
99 | and 3.0.2 patches. Similarly, if you are running kernel version 3.0.2 and | |
100 | want to jump to 3.0.3, you must first reverse the 3.0.2 patch (that is, | |
101 | patch -R) _before_ applying the 3.0.3 patch. You can read more on this in | |
102 | Documentation/applying-patches.txt | |
103 | ||
104 | Alternatively, the script patch-kernel can be used to automate this | |
105 | process. It determines the current kernel version and applies any | |
106 | patches found. | |
107 | ||
108 | linux/scripts/patch-kernel linux | |
109 | ||
110 | The first argument in the command above is the location of the | |
111 | kernel source. Patches are applied from the current directory, but | |
112 | an alternative directory can be specified as the second argument. | |
113 | ||
114 | - Make sure you have no stale .o files and dependencies lying around: | |
115 | ||
116 | cd linux | |
117 | make mrproper | |
118 | ||
119 | You should now have the sources correctly installed. | |
120 | ||
121 | SOFTWARE REQUIREMENTS | |
122 | ||
123 | Compiling and running the 3.x kernels requires up-to-date | |
124 | versions of various software packages. Consult | |
125 | Documentation/Changes for the minimum version numbers required | |
126 | and how to get updates for these packages. Beware that using | |
127 | excessively old versions of these packages can cause indirect | |
128 | errors that are very difficult to track down, so don't assume that | |
129 | you can just update packages when obvious problems arise during | |
130 | build or operation. | |
131 | ||
132 | BUILD directory for the kernel: | |
133 | ||
134 | When compiling the kernel, all output files will per default be | |
135 | stored together with the kernel source code. | |
136 | Using the option "make O=output/dir" allow you to specify an alternate | |
137 | place for the output files (including .config). | |
138 | Example: | |
139 | ||
140 | kernel source code: /usr/src/linux-3.X | |
141 | build directory: /home/name/build/kernel | |
142 | ||
143 | To configure and build the kernel, use: | |
144 | ||
145 | cd /usr/src/linux-3.X | |
146 | make O=/home/name/build/kernel menuconfig | |
147 | make O=/home/name/build/kernel | |
148 | sudo make O=/home/name/build/kernel modules_install install | |
149 | ||
150 | Please note: If the 'O=output/dir' option is used, then it must be | |
151 | used for all invocations of make. | |
152 | ||
153 | CONFIGURING the kernel: | |
154 | ||
155 | Do not skip this step even if you are only upgrading one minor | |
156 | version. New configuration options are added in each release, and | |
157 | odd problems will turn up if the configuration files are not set up | |
158 | as expected. If you want to carry your existing configuration to a | |
159 | new version with minimal work, use "make oldconfig", which will | |
160 | only ask you for the answers to new questions. | |
161 | ||
162 | - Alternative configuration commands are: | |
163 | ||
164 | "make config" Plain text interface. | |
165 | ||
166 | "make menuconfig" Text based color menus, radiolists & dialogs. | |
167 | ||
168 | "make nconfig" Enhanced text based color menus. | |
169 | ||
170 | "make xconfig" X windows (Qt) based configuration tool. | |
171 | ||
172 | "make gconfig" X windows (Gtk) based configuration tool. | |
173 | ||
174 | "make oldconfig" Default all questions based on the contents of | |
175 | your existing ./.config file and asking about | |
176 | new config symbols. | |
177 | ||
178 | "make silentoldconfig" | |
179 | Like above, but avoids cluttering the screen | |
180 | with questions already answered. | |
181 | Additionally updates the dependencies. | |
182 | ||
183 | "make olddefconfig" | |
184 | Like above, but sets new symbols to their default | |
185 | values without prompting. | |
186 | ||
187 | "make defconfig" Create a ./.config file by using the default | |
188 | symbol values from either arch/$ARCH/defconfig | |
189 | or arch/$ARCH/configs/${PLATFORM}_defconfig, | |
190 | depending on the architecture. | |
191 | ||
192 | "make ${PLATFORM}_defconfig" | |
193 | Create a ./.config file by using the default | |
194 | symbol values from | |
195 | arch/$ARCH/configs/${PLATFORM}_defconfig. | |
196 | Use "make help" to get a list of all available | |
197 | platforms of your architecture. | |
198 | ||
199 | "make allyesconfig" | |
200 | Create a ./.config file by setting symbol | |
201 | values to 'y' as much as possible. | |
202 | ||
203 | "make allmodconfig" | |
204 | Create a ./.config file by setting symbol | |
205 | values to 'm' as much as possible. | |
206 | ||
207 | "make allnoconfig" Create a ./.config file by setting symbol | |
208 | values to 'n' as much as possible. | |
209 | ||
210 | "make randconfig" Create a ./.config file by setting symbol | |
211 | values to random values. | |
212 | ||
213 | "make localmodconfig" Create a config based on current config and | |
214 | loaded modules (lsmod). Disables any module | |
215 | option that is not needed for the loaded modules. | |
216 | ||
217 | To create a localmodconfig for another machine, | |
218 | store the lsmod of that machine into a file | |
219 | and pass it in as a LSMOD parameter. | |
220 | ||
221 | target$ lsmod > /tmp/mylsmod | |
222 | target$ scp /tmp/mylsmod host:/tmp | |
223 | ||
224 | host$ make LSMOD=/tmp/mylsmod localmodconfig | |
225 | ||
226 | The above also works when cross compiling. | |
227 | ||
228 | "make localyesconfig" Similar to localmodconfig, except it will convert | |
229 | all module options to built in (=y) options. | |
230 | ||
231 | You can find more information on using the Linux kernel config tools | |
232 | in Documentation/kbuild/kconfig.txt. | |
233 | ||
234 | - NOTES on "make config": | |
235 | ||
236 | - Having unnecessary drivers will make the kernel bigger, and can | |
237 | under some circumstances lead to problems: probing for a | |
238 | nonexistent controller card may confuse your other controllers | |
239 | ||
240 | - Compiling the kernel with "Processor type" set higher than 386 | |
241 | will result in a kernel that does NOT work on a 386. The | |
242 | kernel will detect this on bootup, and give up. | |
243 | ||
244 | - A kernel with math-emulation compiled in will still use the | |
245 | coprocessor if one is present: the math emulation will just | |
246 | never get used in that case. The kernel will be slightly larger, | |
247 | but will work on different machines regardless of whether they | |
248 | have a math coprocessor or not. | |
249 | ||
250 | - The "kernel hacking" configuration details usually result in a | |
251 | bigger or slower kernel (or both), and can even make the kernel | |
252 | less stable by configuring some routines to actively try to | |
253 | break bad code to find kernel problems (kmalloc()). Thus you | |
254 | should probably answer 'n' to the questions for "development", | |
255 | "experimental", or "debugging" features. | |
256 | ||
257 | COMPILING the kernel: | |
258 | ||
259 | - Make sure you have at least gcc 3.2 available. | |
260 | For more information, refer to Documentation/Changes. | |
261 | ||
262 | Please note that you can still run a.out user programs with this kernel. | |
263 | ||
264 | - Do a "make" to create a compressed kernel image. It is also | |
265 | possible to do "make install" if you have lilo installed to suit the | |
266 | kernel makefiles, but you may want to check your particular lilo setup first. | |
267 | ||
268 | To do the actual install, you have to be root, but none of the normal | |
269 | build should require that. Don't take the name of root in vain. | |
270 | ||
271 | - If you configured any of the parts of the kernel as `modules', you | |
272 | will also have to do "make modules_install". | |
273 | ||
274 | - Verbose kernel compile/build output: | |
275 | ||
276 | Normally, the kernel build system runs in a fairly quiet mode (but not | |
277 | totally silent). However, sometimes you or other kernel developers need | |
278 | to see compile, link, or other commands exactly as they are executed. | |
279 | For this, use "verbose" build mode. This is done by inserting | |
280 | "V=1" in the "make" command. E.g.: | |
281 | ||
282 | make V=1 all | |
283 | ||
284 | To have the build system also tell the reason for the rebuild of each | |
285 | target, use "V=2". The default is "V=0". | |
286 | ||
287 | - Keep a backup kernel handy in case something goes wrong. This is | |
288 | especially true for the development releases, since each new release | |
289 | contains new code which has not been debugged. Make sure you keep a | |
290 | backup of the modules corresponding to that kernel, as well. If you | |
291 | are installing a new kernel with the same version number as your | |
292 | working kernel, make a backup of your modules directory before you | |
293 | do a "make modules_install". | |
294 | ||
295 | Alternatively, before compiling, use the kernel config option | |
296 | "LOCALVERSION" to append a unique suffix to the regular kernel version. | |
297 | LOCALVERSION can be set in the "General Setup" menu. | |
298 | ||
299 | - In order to boot your new kernel, you'll need to copy the kernel | |
300 | image (e.g. .../linux/arch/i386/boot/bzImage after compilation) | |
301 | to the place where your regular bootable kernel is found. | |
302 | ||
303 | - Booting a kernel directly from a floppy without the assistance of a | |
304 | bootloader such as LILO, is no longer supported. | |
305 | ||
306 | If you boot Linux from the hard drive, chances are you use LILO, which | |
307 | uses the kernel image as specified in the file /etc/lilo.conf. The | |
308 | kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or | |
309 | /boot/bzImage. To use the new kernel, save a copy of the old image | |
310 | and copy the new image over the old one. Then, you MUST RERUN LILO | |
311 | to update the loading map!! If you don't, you won't be able to boot | |
312 | the new kernel image. | |
313 | ||
314 | Reinstalling LILO is usually a matter of running /sbin/lilo. | |
315 | You may wish to edit /etc/lilo.conf to specify an entry for your | |
316 | old kernel image (say, /vmlinux.old) in case the new one does not | |
317 | work. See the LILO docs for more information. | |
318 | ||
319 | After reinstalling LILO, you should be all set. Shutdown the system, | |
320 | reboot, and enjoy! | |
321 | ||
322 | If you ever need to change the default root device, video mode, | |
323 | ramdisk size, etc. in the kernel image, use the 'rdev' program (or | |
324 | alternatively the LILO boot options when appropriate). No need to | |
325 | recompile the kernel to change these parameters. | |
326 | ||
327 | - Reboot with the new kernel and enjoy. | |
328 | ||
329 | IF SOMETHING GOES WRONG: | |
330 | ||
331 | - If you have problems that seem to be due to kernel bugs, please check | |
332 | the file MAINTAINERS to see if there is a particular person associated | |
333 | with the part of the kernel that you are having trouble with. If there | |
334 | isn't anyone listed there, then the second best thing is to mail | |
335 | them to me (torvalds@linux-foundation.org), and possibly to any other | |
336 | relevant mailing-list or to the newsgroup. | |
337 | ||
338 | - In all bug-reports, *please* tell what kernel you are talking about, | |
339 | how to duplicate the problem, and what your setup is (use your common | |
340 | sense). If the problem is new, tell me so, and if the problem is | |
341 | old, please try to tell me when you first noticed it. | |
342 | ||
343 | - If the bug results in a message like | |
344 | ||
345 | unable to handle kernel paging request at address C0000010 | |
346 | Oops: 0002 | |
347 | EIP: 0010:XXXXXXXX | |
348 | eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx | |
349 | esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx | |
350 | ds: xxxx es: xxxx fs: xxxx gs: xxxx | |
351 | Pid: xx, process nr: xx | |
352 | xx xx xx xx xx xx xx xx xx xx | |
353 | ||
354 | or similar kernel debugging information on your screen or in your | |
355 | system log, please duplicate it *exactly*. The dump may look | |
356 | incomprehensible to you, but it does contain information that may | |
357 | help debugging the problem. The text above the dump is also | |
358 | important: it tells something about why the kernel dumped code (in | |
359 | the above example, it's due to a bad kernel pointer). More information | |
360 | on making sense of the dump is in Documentation/oops-tracing.txt | |
361 | ||
362 | - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump | |
363 | as is, otherwise you will have to use the "ksymoops" program to make | |
364 | sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred). | |
365 | This utility can be downloaded from | |
366 | ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ . | |
367 | Alternatively, you can do the dump lookup by hand: | |
368 | ||
369 | - In debugging dumps like the above, it helps enormously if you can | |
370 | look up what the EIP value means. The hex value as such doesn't help | |
371 | me or anybody else very much: it will depend on your particular | |
372 | kernel setup. What you should do is take the hex value from the EIP | |
373 | line (ignore the "0010:"), and look it up in the kernel namelist to | |
374 | see which kernel function contains the offending address. | |
375 | ||
376 | To find out the kernel function name, you'll need to find the system | |
377 | binary associated with the kernel that exhibited the symptom. This is | |
378 | the file 'linux/vmlinux'. To extract the namelist and match it against | |
379 | the EIP from the kernel crash, do: | |
380 | ||
381 | nm vmlinux | sort | less | |
382 | ||
383 | This will give you a list of kernel addresses sorted in ascending | |
384 | order, from which it is simple to find the function that contains the | |
385 | offending address. Note that the address given by the kernel | |
386 | debugging messages will not necessarily match exactly with the | |
387 | function addresses (in fact, that is very unlikely), so you can't | |
388 | just 'grep' the list: the list will, however, give you the starting | |
389 | point of each kernel function, so by looking for the function that | |
390 | has a starting address lower than the one you are searching for but | |
391 | is followed by a function with a higher address you will find the one | |
392 | you want. In fact, it may be a good idea to include a bit of | |
393 | "context" in your problem report, giving a few lines around the | |
394 | interesting one. | |
395 | ||
396 | If you for some reason cannot do the above (you have a pre-compiled | |
397 | kernel image or similar), telling me as much about your setup as | |
398 | possible will help. Please read the REPORTING-BUGS document for details. | |
399 | ||
400 | - Alternatively, you can use gdb on a running kernel. (read-only; i.e. you | |
401 | cannot change values or set break points.) To do this, first compile the | |
402 | kernel with -g; edit arch/i386/Makefile appropriately, then do a "make | |
403 | clean". You'll also need to enable CONFIG_PROC_FS (via "make config"). | |
404 | ||
405 | After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore". | |
406 | You can now use all the usual gdb commands. The command to look up the | |
407 | point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes | |
408 | with the EIP value.) | |
409 | ||
410 | gdb'ing a non-running kernel currently fails because gdb (wrongly) | |
411 | disregards the starting offset for which the kernel is compiled. | |
412 |