1 Linux kernel release 3.x <http://kernel.org/> 2 3These are the release notes for Linux version 3. Read them carefully, 4as they tell you what this is all about, explain how to install the 5kernel, and what to do if something goes wrong. 6 7WHAT 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 21ON 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 37DOCUMENTATION: 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 59INSTALLING 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. Please read 98 Documentation/applying-patches.txt for more information. 99 100 Alternatively, the script patch-kernel can be used to automate this 101 process. It determines the current kernel version and applies any 102 patches found. 103 104 linux/scripts/patch-kernel linux 105 106 The first argument in the command above is the location of the 107 kernel source. Patches are applied from the current directory, but 108 an alternative directory can be specified as the second argument. 109 110 - If you are upgrading between releases using the stable series patches 111 (for example, patch-3.x.y), note that these "dot-releases" are 112 not incremental and must be applied to the 3.x base tree. For 113 example, if your base kernel is 3.0 and you want to apply the 114 3.0.3 patch, you do not and indeed must not first apply the 115 3.0.1 and 3.0.2 patches. Similarly, if you are running kernel 116 version 3.0.2 and want to jump to 3.0.3, you must first 117 reverse the 3.0.2 patch (that is, patch -R) _before_ applying 118 the 3.0.3 patch. 119 You can read more on this in Documentation/applying-patches.txt 120 121 - Make sure you have no stale .o files and dependencies lying around: 122 123 cd linux 124 make mrproper 125 126 You should now have the sources correctly installed. 127 128SOFTWARE REQUIREMENTS 129 130 Compiling and running the 3.x kernels requires up-to-date 131 versions of various software packages. Consult 132 Documentation/Changes for the minimum version numbers required 133 and how to get updates for these packages. Beware that using 134 excessively old versions of these packages can cause indirect 135 errors that are very difficult to track down, so don't assume that 136 you can just update packages when obvious problems arise during 137 build or operation. 138 139BUILD directory for the kernel: 140 141 When compiling the kernel, all output files will per default be 142 stored together with the kernel source code. 143 Using the option "make O=output/dir" allow you to specify an alternate 144 place for the output files (including .config). 145 Example: 146 147 kernel source code: /usr/src/linux-3.X 148 build directory: /home/name/build/kernel 149 150 To configure and build the kernel, use: 151 152 cd /usr/src/linux-3.X 153 make O=/home/name/build/kernel menuconfig 154 make O=/home/name/build/kernel 155 sudo make O=/home/name/build/kernel modules_install install 156 157 Please note: If the 'O=output/dir' option is used, then it must be 158 used for all invocations of make. 159 160CONFIGURING the kernel: 161 162 Do not skip this step even if you are only upgrading one minor 163 version. New configuration options are added in each release, and 164 odd problems will turn up if the configuration files are not set up 165 as expected. If you want to carry your existing configuration to a 166 new version with minimal work, use "make oldconfig", which will 167 only ask you for the answers to new questions. 168 169 - Alternative configuration commands are: 170 171 "make config" Plain text interface. 172 173 "make menuconfig" Text based color menus, radiolists & dialogs. 174 175 "make nconfig" Enhanced text based color menus. 176 177 "make xconfig" X windows (Qt) based configuration tool. 178 179 "make gconfig" X windows (Gtk) based configuration tool. 180 181 "make oldconfig" Default all questions based on the contents of 182 your existing ./.config file and asking about 183 new config symbols. 184 185 "make silentoldconfig" 186 Like above, but avoids cluttering the screen 187 with questions already answered. 188 Additionally updates the dependencies. 189 190 "make defconfig" Create a ./.config file by using the default 191 symbol values from either arch/$ARCH/defconfig 192 or arch/$ARCH/configs/${PLATFORM}_defconfig, 193 depending on the architecture. 194 195 "make ${PLATFORM}_defconfig" 196 Create a ./.config file by using the default 197 symbol values from 198 arch/$ARCH/configs/${PLATFORM}_defconfig. 199 Use "make help" to get a list of all available 200 platforms of your architecture. 201 202 "make allyesconfig" 203 Create a ./.config file by setting symbol 204 values to 'y' as much as possible. 205 206 "make allmodconfig" 207 Create a ./.config file by setting symbol 208 values to 'm' as much as possible. 209 210 "make allnoconfig" Create a ./.config file by setting symbol 211 values to 'n' as much as possible. 212 213 "make randconfig" Create a ./.config file by setting symbol 214 values to random values. 215 216 You can find more information on using the Linux kernel config tools 217 in Documentation/kbuild/kconfig.txt. 218 219 NOTES on "make config": 220 221 - Having unnecessary drivers will make the kernel bigger, and can 222 under some circumstances lead to problems: probing for a 223 nonexistent controller card may confuse your other controllers 224 225 - Compiling the kernel with "Processor type" set higher than 386 226 will result in a kernel that does NOT work on a 386. The 227 kernel will detect this on bootup, and give up. 228 229 - A kernel with math-emulation compiled in will still use the 230 coprocessor if one is present: the math emulation will just 231 never get used in that case. The kernel will be slightly larger, 232 but will work on different machines regardless of whether they 233 have a math coprocessor or not. 234 235 - The "kernel hacking" configuration details usually result in a 236 bigger or slower kernel (or both), and can even make the kernel 237 less stable by configuring some routines to actively try to 238 break bad code to find kernel problems (kmalloc()). Thus you 239 should probably answer 'n' to the questions for 240 "development", "experimental", or "debugging" features. 241 242COMPILING the kernel: 243 244 - Make sure you have at least gcc 3.2 available. 245 For more information, refer to Documentation/Changes. 246 247 Please note that you can still run a.out user programs with this kernel. 248 249 - Do a "make" to create a compressed kernel image. It is also 250 possible to do "make install" if you have lilo installed to suit the 251 kernel makefiles, but you may want to check your particular lilo setup first. 252 253 To do the actual install, you have to be root, but none of the normal 254 build should require that. Don't take the name of root in vain. 255 256 - If you configured any of the parts of the kernel as `modules', you 257 will also have to do "make modules_install". 258 259 - Verbose kernel compile/build output: 260 261 Normally, the kernel build system runs in a fairly quiet mode (but not 262 totally silent). However, sometimes you or other kernel developers need 263 to see compile, link, or other commands exactly as they are executed. 264 For this, use "verbose" build mode. This is done by inserting 265 "V=1" in the "make" command. E.g.: 266 267 make V=1 all 268 269 To have the build system also tell the reason for the rebuild of each 270 target, use "V=2". The default is "V=0". 271 272 - Keep a backup kernel handy in case something goes wrong. This is 273 especially true for the development releases, since each new release 274 contains new code which has not been debugged. Make sure you keep a 275 backup of the modules corresponding to that kernel, as well. If you 276 are installing a new kernel with the same version number as your 277 working kernel, make a backup of your modules directory before you 278 do a "make modules_install". 279 280 Alternatively, before compiling, use the kernel config option 281 "LOCALVERSION" to append a unique suffix to the regular kernel version. 282 LOCALVERSION can be set in the "General Setup" menu. 283 284 - In order to boot your new kernel, you'll need to copy the kernel 285 image (e.g. .../linux/arch/i386/boot/bzImage after compilation) 286 to the place where your regular bootable kernel is found. 287 288 - Booting a kernel directly from a floppy without the assistance of a 289 bootloader such as LILO, is no longer supported. 290 291 If you boot Linux from the hard drive, chances are you use LILO, which 292 uses the kernel image as specified in the file /etc/lilo.conf. The 293 kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or 294 /boot/bzImage. To use the new kernel, save a copy of the old image 295 and copy the new image over the old one. Then, you MUST RERUN LILO 296 to update the loading map!! If you don't, you won't be able to boot 297 the new kernel image. 298 299 Reinstalling LILO is usually a matter of running /sbin/lilo. 300 You may wish to edit /etc/lilo.conf to specify an entry for your 301 old kernel image (say, /vmlinux.old) in case the new one does not 302 work. See the LILO docs for more information. 303 304 After reinstalling LILO, you should be all set. Shutdown the system, 305 reboot, and enjoy! 306 307 If you ever need to change the default root device, video mode, 308 ramdisk size, etc. in the kernel image, use the 'rdev' program (or 309 alternatively the LILO boot options when appropriate). No need to 310 recompile the kernel to change these parameters. 311 312 - Reboot with the new kernel and enjoy. 313 314IF SOMETHING GOES WRONG: 315 316 - If you have problems that seem to be due to kernel bugs, please check 317 the file MAINTAINERS to see if there is a particular person associated 318 with the part of the kernel that you are having trouble with. If there 319 isn't anyone listed there, then the second best thing is to mail 320 them to me (torvalds@linux-foundation.org), and possibly to any other 321 relevant mailing-list or to the newsgroup. 322 323 - In all bug-reports, *please* tell what kernel you are talking about, 324 how to duplicate the problem, and what your setup is (use your common 325 sense). If the problem is new, tell me so, and if the problem is 326 old, please try to tell me when you first noticed it. 327 328 - If the bug results in a message like 329 330 unable to handle kernel paging request at address C0000010 331 Oops: 0002 332 EIP: 0010:XXXXXXXX 333 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx 334 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx 335 ds: xxxx es: xxxx fs: xxxx gs: xxxx 336 Pid: xx, process nr: xx 337 xx xx xx xx xx xx xx xx xx xx 338 339 or similar kernel debugging information on your screen or in your 340 system log, please duplicate it *exactly*. The dump may look 341 incomprehensible to you, but it does contain information that may 342 help debugging the problem. The text above the dump is also 343 important: it tells something about why the kernel dumped code (in 344 the above example, it's due to a bad kernel pointer). More information 345 on making sense of the dump is in Documentation/oops-tracing.txt 346 347 - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump 348 as is, otherwise you will have to use the "ksymoops" program to make 349 sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred). 350 This utility can be downloaded from 351 ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ . 352 Alternatively, you can do the dump lookup by hand: 353 354 - In debugging dumps like the above, it helps enormously if you can 355 look up what the EIP value means. The hex value as such doesn't help 356 me or anybody else very much: it will depend on your particular 357 kernel setup. What you should do is take the hex value from the EIP 358 line (ignore the "0010:"), and look it up in the kernel namelist to 359 see which kernel function contains the offending address. 360 361 To find out the kernel function name, you'll need to find the system 362 binary associated with the kernel that exhibited the symptom. This is 363 the file 'linux/vmlinux'. To extract the namelist and match it against 364 the EIP from the kernel crash, do: 365 366 nm vmlinux | sort | less 367 368 This will give you a list of kernel addresses sorted in ascending 369 order, from which it is simple to find the function that contains the 370 offending address. Note that the address given by the kernel 371 debugging messages will not necessarily match exactly with the 372 function addresses (in fact, that is very unlikely), so you can't 373 just 'grep' the list: the list will, however, give you the starting 374 point of each kernel function, so by looking for the function that 375 has a starting address lower than the one you are searching for but 376 is followed by a function with a higher address you will find the one 377 you want. In fact, it may be a good idea to include a bit of 378 "context" in your problem report, giving a few lines around the 379 interesting one. 380 381 If you for some reason cannot do the above (you have a pre-compiled 382 kernel image or similar), telling me as much about your setup as 383 possible will help. Please read the REPORTING-BUGS document for details. 384 385 - Alternatively, you can use gdb on a running kernel. (read-only; i.e. you 386 cannot change values or set break points.) To do this, first compile the 387 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make 388 clean". You'll also need to enable CONFIG_PROC_FS (via "make config"). 389 390 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore". 391 You can now use all the usual gdb commands. The command to look up the 392 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes 393 with the EIP value.) 394 395 gdb'ing a non-running kernel currently fails because gdb (wrongly) 396 disregards the starting offset for which the kernel is compiled. 397 398