Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 1 | Linux kernel release 3.x <http://kernel.org/> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 3 | These are the release notes for Linux version 3. Read them carefully, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Xose Vazquez Perez | 4f4e2dc | 2006-01-14 19:56:28 +0100 | [diff] [blame] | 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. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 12 | |
Xose Vazquez Perez | 4f4e2dc | 2006-01-14 19:56:28 +0100 | [diff] [blame] | 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. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Xose Vazquez Perez | 4f4e2dc | 2006-01-14 19:56:28 +0100 | [diff] [blame] | 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 |
Jesper Juhl | 620034c | 2006-12-07 00:45:58 +0100 | [diff] [blame] | 25 | UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell, |
Xose Vazquez Perez | 4f4e2dc | 2006-01-14 19:56:28 +0100 | [diff] [blame] | 26 | IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS, |
Tracey Dent | cddb5de0 | 2010-11-24 06:56:36 -0500 | [diff] [blame] | 27 | Xtensa, Tilera TILE, AVR32 and Renesas M32R architectures. |
Xose Vazquez Perez | 4f4e2dc | 2006-01-14 19:56:28 +0100 | [diff] [blame] | 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. |
Jesper Juhl | 620034c | 2006-12-07 00:45:58 +0100 | [diff] [blame] | 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). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 |
Randy Dunlap | 2af238e4 | 2008-02-29 14:21:53 -0800 | [diff] [blame] | 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. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 58 | |
Randy Dunlap | 2af238e4 | 2008-02-29 14:21:53 -0800 | [diff] [blame] | 59 | INSTALLING the kernel source: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 65 | gzip -cd linux-3.X.tar.gz | tar xvf - |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 66 | |
Horms | b39f72f | 2005-10-30 15:03:19 -0800 | [diff] [blame] | 67 | or |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 68 | bzip2 -dc linux-3.X.tar.bz2 | tar xvf - |
Horms | b39f72f | 2005-10-30 15:03:19 -0800 | [diff] [blame] | 69 | |
| 70 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 71 | Replace "XX" 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 | |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 78 | - You can also upgrade between 3.x releases by patching. Patches are |
Håkon Løvdal | 2b42238 | 2006-03-20 20:32:04 +0100 | [diff] [blame] | 79 | distributed in the traditional gzip and the newer bzip2 format. To |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 80 | install by patching, get all the newer patch files, enter the |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 81 | top level directory of the kernel source (linux-3.x) and execute: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 82 | |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 83 | gzip -cd ../patch-3.x.gz | patch -p1 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 84 | |
| 85 | or |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 86 | bzip2 -dc ../patch-3.x.bz2 | patch -p1 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 87 | |
| 88 | (repeat xx for all versions bigger than the version of your current |
| 89 | source tree, _in_order_) and you should be ok. You may want to remove |
| 90 | the backup files (xxx~ or xxx.orig), and make sure that there are no |
| 91 | failed patches (xxx# or xxx.rej). If there are, either you or me has |
| 92 | made a mistake. |
| 93 | |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 94 | Unlike patches for the 3.x kernels, patches for the 3.x.y kernels |
Jesper Juhl | 6ad4422 | 2005-11-13 16:07:44 -0800 | [diff] [blame] | 95 | (also known as the -stable kernels) are not incremental but instead apply |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 96 | directly to the base 3.x kernel. Please read |
Jesper Juhl | 6ad4422 | 2005-11-13 16:07:44 -0800 | [diff] [blame] | 97 | Documentation/applying-patches.txt for more information. |
| 98 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 99 | Alternatively, the script patch-kernel can be used to automate this |
| 100 | process. It determines the current kernel version and applies any |
| 101 | patches found. |
| 102 | |
| 103 | linux/scripts/patch-kernel linux |
| 104 | |
| 105 | The first argument in the command above is the location of the |
| 106 | kernel source. Patches are applied from the current directory, but |
| 107 | an alternative directory can be specified as the second argument. |
| 108 | |
Kurt Wall | 896e551 | 2005-07-27 11:45:20 -0700 | [diff] [blame] | 109 | - If you are upgrading between releases using the stable series patches |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 110 | (for example, patch-3.x.y), note that these "dot-releases" are |
| 111 | not incremental and must be applied to the 3.x base tree. For |
| 112 | example, if your base kernel is 3.0 and you want to apply the |
| 113 | 3.0.3 patch, you do not and indeed must not first apply the |
| 114 | 3.0.1 and 3.0.2 patches. Similarly, if you are running kernel |
| 115 | version 3.0.2 and want to jump to 3.0.3, you must first |
| 116 | reverse the 3.0.2 patch (that is, patch -R) _before_ applying |
| 117 | the 3.0.3 patch. |
Jesper Juhl | 620034c | 2006-12-07 00:45:58 +0100 | [diff] [blame] | 118 | You can read more on this in Documentation/applying-patches.txt |
Kurt Wall | 896e551 | 2005-07-27 11:45:20 -0700 | [diff] [blame] | 119 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 120 | - Make sure you have no stale .o files and dependencies lying around: |
| 121 | |
| 122 | cd linux |
| 123 | make mrproper |
| 124 | |
| 125 | You should now have the sources correctly installed. |
| 126 | |
| 127 | SOFTWARE REQUIREMENTS |
| 128 | |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 129 | Compiling and running the 3.x kernels requires up-to-date |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 130 | versions of various software packages. Consult |
| 131 | Documentation/Changes for the minimum version numbers required |
| 132 | and how to get updates for these packages. Beware that using |
| 133 | excessively old versions of these packages can cause indirect |
| 134 | errors that are very difficult to track down, so don't assume that |
| 135 | you can just update packages when obvious problems arise during |
| 136 | build or operation. |
| 137 | |
| 138 | BUILD directory for the kernel: |
| 139 | |
| 140 | When compiling the kernel all output files will per default be |
| 141 | stored together with the kernel source code. |
| 142 | Using the option "make O=output/dir" allow you to specify an alternate |
| 143 | place for the output files (including .config). |
| 144 | Example: |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 145 | kernel source code: /usr/src/linux-3.N |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 146 | build directory: /home/name/build/kernel |
| 147 | |
| 148 | To configure and build the kernel use: |
Jesper Juhl | 0466dcb | 2011-07-01 12:46:56 +0200 | [diff] [blame] | 149 | cd /usr/src/linux-3.N |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 150 | make O=/home/name/build/kernel menuconfig |
| 151 | make O=/home/name/build/kernel |
| 152 | sudo make O=/home/name/build/kernel modules_install install |
| 153 | |
| 154 | Please note: If the 'O=output/dir' option is used then it must be |
| 155 | used for all invocations of make. |
| 156 | |
| 157 | CONFIGURING the kernel: |
| 158 | |
| 159 | Do not skip this step even if you are only upgrading one minor |
| 160 | version. New configuration options are added in each release, and |
| 161 | odd problems will turn up if the configuration files are not set up |
| 162 | as expected. If you want to carry your existing configuration to a |
| 163 | new version with minimal work, use "make oldconfig", which will |
| 164 | only ask you for the answers to new questions. |
| 165 | |
| 166 | - Alternate configuration commands are: |
Jesper Juhl | 620034c | 2006-12-07 00:45:58 +0100 | [diff] [blame] | 167 | "make config" Plain text interface. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 168 | "make menuconfig" Text based color menus, radiolists & dialogs. |
Andrea Gelmini | b3235fe | 2010-10-01 14:15:35 -0700 | [diff] [blame] | 169 | "make nconfig" Enhanced text based color menus. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 170 | "make xconfig" X windows (Qt) based configuration tool. |
| 171 | "make gconfig" X windows (Gtk) based configuration tool. |
| 172 | "make oldconfig" Default all questions based on the contents of |
Randy Dunlap | 9dfb563 | 2006-04-18 22:21:53 -0700 | [diff] [blame] | 173 | your existing ./.config file and asking about |
| 174 | new config symbols. |
Paolo 'Blaisorblade' Giarrusso | f875a1a | 2005-09-21 09:55:37 -0700 | [diff] [blame] | 175 | "make silentoldconfig" |
| 176 | Like above, but avoids cluttering the screen |
Randy Dunlap | e3fc4cc | 2005-09-22 21:44:07 -0700 | [diff] [blame] | 177 | with questions already answered. |
Markus Heidelberg | 590a585 | 2009-05-18 01:36:46 +0200 | [diff] [blame] | 178 | Additionally updates the dependencies. |
Randy Dunlap | 9dfb563 | 2006-04-18 22:21:53 -0700 | [diff] [blame] | 179 | "make defconfig" Create a ./.config file by using the default |
Patrick Ringl | b2d8993 | 2009-06-12 13:58:36 +0200 | [diff] [blame] | 180 | symbol values from either arch/$ARCH/defconfig |
| 181 | or arch/$ARCH/configs/${PLATFORM}_defconfig, |
| 182 | depending on the architecture. |
| 183 | "make ${PLATFORM}_defconfig" |
| 184 | Create a ./.config file by using the default |
| 185 | symbol values from |
| 186 | arch/$ARCH/configs/${PLATFORM}_defconfig. |
| 187 | Use "make help" to get a list of all available |
| 188 | platforms of your architecture. |
Randy Dunlap | 9dfb563 | 2006-04-18 22:21:53 -0700 | [diff] [blame] | 189 | "make allyesconfig" |
| 190 | Create a ./.config file by setting symbol |
| 191 | values to 'y' as much as possible. |
| 192 | "make allmodconfig" |
| 193 | Create a ./.config file by setting symbol |
| 194 | values to 'm' as much as possible. |
| 195 | "make allnoconfig" Create a ./.config file by setting symbol |
| 196 | values to 'n' as much as possible. |
| 197 | "make randconfig" Create a ./.config file by setting symbol |
| 198 | values to random values. |
| 199 | |
Randy Dunlap | 2af238e4 | 2008-02-29 14:21:53 -0800 | [diff] [blame] | 200 | You can find more information on using the Linux kernel config tools |
Li Zefan | ad44468 | 2009-02-20 15:38:43 -0800 | [diff] [blame] | 201 | in Documentation/kbuild/kconfig.txt. |
Randy Dunlap | 2af238e4 | 2008-02-29 14:21:53 -0800 | [diff] [blame] | 202 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 203 | NOTES on "make config": |
| 204 | - having unnecessary drivers will make the kernel bigger, and can |
| 205 | under some circumstances lead to problems: probing for a |
| 206 | nonexistent controller card may confuse your other controllers |
| 207 | - compiling the kernel with "Processor type" set higher than 386 |
| 208 | will result in a kernel that does NOT work on a 386. The |
| 209 | kernel will detect this on bootup, and give up. |
| 210 | - A kernel with math-emulation compiled in will still use the |
| 211 | coprocessor if one is present: the math emulation will just |
| 212 | never get used in that case. The kernel will be slightly larger, |
| 213 | but will work on different machines regardless of whether they |
| 214 | have a math coprocessor or not. |
| 215 | - the "kernel hacking" configuration details usually result in a |
| 216 | bigger or slower kernel (or both), and can even make the kernel |
| 217 | less stable by configuring some routines to actively try to |
| 218 | break bad code to find kernel problems (kmalloc()). Thus you |
| 219 | should probably answer 'n' to the questions for |
| 220 | "development", "experimental", or "debugging" features. |
| 221 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 222 | COMPILING the kernel: |
| 223 | |
Andrew Morton | a136564 | 2006-01-08 01:04:09 -0800 | [diff] [blame] | 224 | - Make sure you have at least gcc 3.2 available. |
| 225 | For more information, refer to Documentation/Changes. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 226 | |
| 227 | Please note that you can still run a.out user programs with this kernel. |
| 228 | |
| 229 | - Do a "make" to create a compressed kernel image. It is also |
| 230 | possible to do "make install" if you have lilo installed to suit the |
| 231 | kernel makefiles, but you may want to check your particular lilo setup first. |
| 232 | |
| 233 | To do the actual install you have to be root, but none of the normal |
| 234 | build should require that. Don't take the name of root in vain. |
| 235 | |
| 236 | - If you configured any of the parts of the kernel as `modules', you |
| 237 | will also have to do "make modules_install". |
| 238 | |
Randy Dunlap | 2af238e4 | 2008-02-29 14:21:53 -0800 | [diff] [blame] | 239 | - Verbose kernel compile/build output: |
| 240 | |
| 241 | Normally the kernel build system runs in a fairly quiet mode (but not |
| 242 | totally silent). However, sometimes you or other kernel developers need |
| 243 | to see compile, link, or other commands exactly as they are executed. |
| 244 | For this, use "verbose" build mode. This is done by inserting |
| 245 | "V=1" in the "make" command. E.g.: |
| 246 | |
| 247 | make V=1 all |
| 248 | |
| 249 | To have the build system also tell the reason for the rebuild of each |
| 250 | target, use "V=2". The default is "V=0". |
| 251 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 252 | - Keep a backup kernel handy in case something goes wrong. This is |
| 253 | especially true for the development releases, since each new release |
| 254 | contains new code which has not been debugged. Make sure you keep a |
| 255 | backup of the modules corresponding to that kernel, as well. If you |
| 256 | are installing a new kernel with the same version number as your |
| 257 | working kernel, make a backup of your modules directory before you |
| 258 | do a "make modules_install". |
Randy Dunlap | e3fc4cc | 2005-09-22 21:44:07 -0700 | [diff] [blame] | 259 | Alternatively, before compiling, use the kernel config option |
| 260 | "LOCALVERSION" to append a unique suffix to the regular kernel version. |
| 261 | LOCALVERSION can be set in the "General Setup" menu. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 262 | |
| 263 | - In order to boot your new kernel, you'll need to copy the kernel |
| 264 | image (e.g. .../linux/arch/i386/boot/bzImage after compilation) |
| 265 | to the place where your regular bootable kernel is found. |
| 266 | |
| 267 | - Booting a kernel directly from a floppy without the assistance of a |
| 268 | bootloader such as LILO, is no longer supported. |
| 269 | |
| 270 | If you boot Linux from the hard drive, chances are you use LILO which |
| 271 | uses the kernel image as specified in the file /etc/lilo.conf. The |
| 272 | kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or |
| 273 | /boot/bzImage. To use the new kernel, save a copy of the old image |
| 274 | and copy the new image over the old one. Then, you MUST RERUN LILO |
| 275 | to update the loading map!! If you don't, you won't be able to boot |
| 276 | the new kernel image. |
| 277 | |
| 278 | Reinstalling LILO is usually a matter of running /sbin/lilo. |
| 279 | You may wish to edit /etc/lilo.conf to specify an entry for your |
| 280 | old kernel image (say, /vmlinux.old) in case the new one does not |
| 281 | work. See the LILO docs for more information. |
| 282 | |
| 283 | After reinstalling LILO, you should be all set. Shutdown the system, |
| 284 | reboot, and enjoy! |
| 285 | |
| 286 | If you ever need to change the default root device, video mode, |
| 287 | ramdisk size, etc. in the kernel image, use the 'rdev' program (or |
| 288 | alternatively the LILO boot options when appropriate). No need to |
| 289 | recompile the kernel to change these parameters. |
| 290 | |
| 291 | - Reboot with the new kernel and enjoy. |
| 292 | |
| 293 | IF SOMETHING GOES WRONG: |
| 294 | |
| 295 | - If you have problems that seem to be due to kernel bugs, please check |
| 296 | the file MAINTAINERS to see if there is a particular person associated |
| 297 | with the part of the kernel that you are having trouble with. If there |
| 298 | isn't anyone listed there, then the second best thing is to mail |
Linus Torvalds | 99ddcc7 | 2007-01-23 14:22:35 -0800 | [diff] [blame] | 299 | them to me (torvalds@linux-foundation.org), and possibly to any other |
| 300 | relevant mailing-list or to the newsgroup. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 301 | |
| 302 | - In all bug-reports, *please* tell what kernel you are talking about, |
| 303 | how to duplicate the problem, and what your setup is (use your common |
| 304 | sense). If the problem is new, tell me so, and if the problem is |
| 305 | old, please try to tell me when you first noticed it. |
| 306 | |
| 307 | - If the bug results in a message like |
| 308 | |
| 309 | unable to handle kernel paging request at address C0000010 |
| 310 | Oops: 0002 |
| 311 | EIP: 0010:XXXXXXXX |
| 312 | eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx |
| 313 | esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx |
| 314 | ds: xxxx es: xxxx fs: xxxx gs: xxxx |
| 315 | Pid: xx, process nr: xx |
| 316 | xx xx xx xx xx xx xx xx xx xx |
| 317 | |
| 318 | or similar kernel debugging information on your screen or in your |
| 319 | system log, please duplicate it *exactly*. The dump may look |
| 320 | incomprehensible to you, but it does contain information that may |
| 321 | help debugging the problem. The text above the dump is also |
| 322 | important: it tells something about why the kernel dumped code (in |
| 323 | the above example it's due to a bad kernel pointer). More information |
| 324 | on making sense of the dump is in Documentation/oops-tracing.txt |
| 325 | |
| 326 | - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump |
| 327 | as is, otherwise you will have to use the "ksymoops" program to make |
Jesper Juhl | 620034c | 2006-12-07 00:45:58 +0100 | [diff] [blame] | 328 | sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred). |
| 329 | This utility can be downloaded from |
| 330 | ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ . |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 331 | Alternately you can do the dump lookup by hand: |
| 332 | |
| 333 | - In debugging dumps like the above, it helps enormously if you can |
| 334 | look up what the EIP value means. The hex value as such doesn't help |
| 335 | me or anybody else very much: it will depend on your particular |
| 336 | kernel setup. What you should do is take the hex value from the EIP |
| 337 | line (ignore the "0010:"), and look it up in the kernel namelist to |
| 338 | see which kernel function contains the offending address. |
| 339 | |
| 340 | To find out the kernel function name, you'll need to find the system |
| 341 | binary associated with the kernel that exhibited the symptom. This is |
| 342 | the file 'linux/vmlinux'. To extract the namelist and match it against |
| 343 | the EIP from the kernel crash, do: |
| 344 | |
| 345 | nm vmlinux | sort | less |
| 346 | |
| 347 | This will give you a list of kernel addresses sorted in ascending |
| 348 | order, from which it is simple to find the function that contains the |
| 349 | offending address. Note that the address given by the kernel |
| 350 | debugging messages will not necessarily match exactly with the |
| 351 | function addresses (in fact, that is very unlikely), so you can't |
| 352 | just 'grep' the list: the list will, however, give you the starting |
| 353 | point of each kernel function, so by looking for the function that |
| 354 | has a starting address lower than the one you are searching for but |
| 355 | is followed by a function with a higher address you will find the one |
| 356 | you want. In fact, it may be a good idea to include a bit of |
| 357 | "context" in your problem report, giving a few lines around the |
| 358 | interesting one. |
| 359 | |
| 360 | If you for some reason cannot do the above (you have a pre-compiled |
| 361 | kernel image or similar), telling me as much about your setup as |
Jesper Juhl | 620034c | 2006-12-07 00:45:58 +0100 | [diff] [blame] | 362 | possible will help. Please read the REPORTING-BUGS document for details. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 363 | |
| 364 | - Alternately, you can use gdb on a running kernel. (read-only; i.e. you |
| 365 | cannot change values or set break points.) To do this, first compile the |
| 366 | kernel with -g; edit arch/i386/Makefile appropriately, then do a "make |
| 367 | clean". You'll also need to enable CONFIG_PROC_FS (via "make config"). |
| 368 | |
| 369 | After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore". |
| 370 | You can now use all the usual gdb commands. The command to look up the |
| 371 | point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes |
| 372 | with the EIP value.) |
| 373 | |
| 374 | gdb'ing a non-running kernel currently fails because gdb (wrongly) |
| 375 | disregards the starting offset for which the kernel is compiled. |
| 376 | |