1 Linux kernel release 2.6.xx <http://kernel.org> 2 3These are the release notes for Linux version 2.6. 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, 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 35DOCUMENTATION: 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 57INSTALLING 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 124SOFTWARE 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 135BUILD 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 154CONFIGURING 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 and asking about 169 new config symbols. 170 "make silentoldconfig" 171 Like above, but avoids cluttering the screen 172 with questions already answered. 173 "make defconfig" Create a ./.config file by using the default 174 symbol values from arch/$ARCH/defconfig. 175 "make allyesconfig" 176 Create a ./.config file by setting symbol 177 values to 'y' as much as possible. 178 "make allmodconfig" 179 Create a ./.config file by setting symbol 180 values to 'm' as much as possible. 181 "make allnoconfig" Create a ./.config file by setting symbol 182 values to 'n' as much as possible. 183 "make randconfig" Create a ./.config file by setting symbol 184 values to random values. 185 186 The allyesconfig/allmodconfig/allnoconfig/randconfig variants can 187 also use the environment variable KCONFIG_ALLCONFIG to specify a 188 filename that contains config options that the user requires to be 189 set to a specific value. If KCONFIG_ALLCONFIG=filename is not used, 190 "make *config" checks for a file named "all{yes/mod/no/random}.config" 191 for symbol values that are to be forced. If this file is not found, 192 it checks for a file named "all.config" to contain forced values. 193 194 NOTES on "make config": 195 - having unnecessary drivers will make the kernel bigger, and can 196 under some circumstances lead to problems: probing for a 197 nonexistent controller card may confuse your other controllers 198 - compiling the kernel with "Processor type" set higher than 386 199 will result in a kernel that does NOT work on a 386. The 200 kernel will detect this on bootup, and give up. 201 - A kernel with math-emulation compiled in will still use the 202 coprocessor if one is present: the math emulation will just 203 never get used in that case. The kernel will be slightly larger, 204 but will work on different machines regardless of whether they 205 have a math coprocessor or not. 206 - the "kernel hacking" configuration details usually result in a 207 bigger or slower kernel (or both), and can even make the kernel 208 less stable by configuring some routines to actively try to 209 break bad code to find kernel problems (kmalloc()). Thus you 210 should probably answer 'n' to the questions for 211 "development", "experimental", or "debugging" features. 212 213COMPILING the kernel: 214 215 - Make sure you have at least gcc 3.2 available. 216 For more information, refer to Documentation/Changes. 217 218 Please note that you can still run a.out user programs with this kernel. 219 220 - Do a "make" to create a compressed kernel image. It is also 221 possible to do "make install" if you have lilo installed to suit the 222 kernel makefiles, but you may want to check your particular lilo setup first. 223 224 To do the actual install you have to be root, but none of the normal 225 build should require that. Don't take the name of root in vain. 226 227 - If you configured any of the parts of the kernel as `modules', you 228 will also have to do "make modules_install". 229 230 - Keep a backup kernel handy in case something goes wrong. This is 231 especially true for the development releases, since each new release 232 contains new code which has not been debugged. Make sure you keep a 233 backup of the modules corresponding to that kernel, as well. If you 234 are installing a new kernel with the same version number as your 235 working kernel, make a backup of your modules directory before you 236 do a "make modules_install". 237 Alternatively, before compiling, use the kernel config option 238 "LOCALVERSION" to append a unique suffix to the regular kernel version. 239 LOCALVERSION can be set in the "General Setup" menu. 240 241 - In order to boot your new kernel, you'll need to copy the kernel 242 image (e.g. .../linux/arch/i386/boot/bzImage after compilation) 243 to the place where your regular bootable kernel is found. 244 245 - Booting a kernel directly from a floppy without the assistance of a 246 bootloader such as LILO, is no longer supported. 247 248 If you boot Linux from the hard drive, chances are you use LILO which 249 uses the kernel image as specified in the file /etc/lilo.conf. The 250 kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or 251 /boot/bzImage. To use the new kernel, save a copy of the old image 252 and copy the new image over the old one. Then, you MUST RERUN LILO 253 to update the loading map!! If you don't, you won't be able to boot 254 the new kernel image. 255 256 Reinstalling LILO is usually a matter of running /sbin/lilo. 257 You may wish to edit /etc/lilo.conf to specify an entry for your 258 old kernel image (say, /vmlinux.old) in case the new one does not 259 work. See the LILO docs for more information. 260 261 After reinstalling LILO, you should be all set. Shutdown the system, 262 reboot, and enjoy! 263 264 If you ever need to change the default root device, video mode, 265 ramdisk size, etc. in the kernel image, use the 'rdev' program (or 266 alternatively the LILO boot options when appropriate). No need to 267 recompile the kernel to change these parameters. 268 269 - Reboot with the new kernel and enjoy. 270 271IF SOMETHING GOES WRONG: 272 273 - If you have problems that seem to be due to kernel bugs, please check 274 the file MAINTAINERS to see if there is a particular person associated 275 with the part of the kernel that you are having trouble with. If there 276 isn't anyone listed there, then the second best thing is to mail 277 them to me (torvalds@osdl.org), and possibly to any other relevant 278 mailing-list or to the newsgroup. 279 280 - In all bug-reports, *please* tell what kernel you are talking about, 281 how to duplicate the problem, and what your setup is (use your common 282 sense). If the problem is new, tell me so, and if the problem is 283 old, please try to tell me when you first noticed it. 284 285 - If the bug results in a message like 286 287 unable to handle kernel paging request at address C0000010 288 Oops: 0002 289 EIP: 0010:XXXXXXXX 290 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx 291 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx 292 ds: xxxx es: xxxx fs: xxxx gs: xxxx 293 Pid: xx, process nr: xx 294 xx xx xx xx xx xx xx xx xx xx 295 296 or similar kernel debugging information on your screen or in your 297 system log, please duplicate it *exactly*. The dump may look 298 incomprehensible to you, but it does contain information that may 299 help debugging the problem. The text above the dump is also 300 important: it tells something about why the kernel dumped code (in 301 the above example it's due to a bad kernel pointer). More information 302 on making sense of the dump is in Documentation/oops-tracing.txt 303 304 - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump 305 as is, otherwise you will have to use the "ksymoops" program to make 306 sense of the dump. This utility can be downloaded from 307 ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops. 308 Alternately you can do the dump lookup by hand: 309 310 - In debugging dumps like the above, it helps enormously if you can 311 look up what the EIP value means. The hex value as such doesn't help 312 me or anybody else very much: it will depend on your particular 313 kernel setup. What you should do is take the hex value from the EIP 314 line (ignore the "0010:"), and look it up in the kernel namelist to 315 see which kernel function contains the offending address. 316 317 To find out the kernel function name, you'll need to find the system 318 binary associated with the kernel that exhibited the symptom. This is 319 the file 'linux/vmlinux'. To extract the namelist and match it against 320 the EIP from the kernel crash, do: 321 322 nm vmlinux | sort | less 323 324 This will give you a list of kernel addresses sorted in ascending 325 order, from which it is simple to find the function that contains the 326 offending address. Note that the address given by the kernel 327 debugging messages will not necessarily match exactly with the 328 function addresses (in fact, that is very unlikely), so you can't 329 just 'grep' the list: the list will, however, give you the starting 330 point of each kernel function, so by looking for the function that 331 has a starting address lower than the one you are searching for but 332 is followed by a function with a higher address you will find the one 333 you want. In fact, it may be a good idea to include a bit of 334 "context" in your problem report, giving a few lines around the 335 interesting one. 336 337 If you for some reason cannot do the above (you have a pre-compiled 338 kernel image or similar), telling me as much about your setup as 339 possible will help. 340 341 - Alternately, you can use gdb on a running kernel. (read-only; i.e. you 342 cannot change values or set break points.) To do this, first compile the 343 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make 344 clean". You'll also need to enable CONFIG_PROC_FS (via "make config"). 345 346 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore". 347 You can now use all the usual gdb commands. The command to look up the 348 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes 349 with the EIP value.) 350 351 gdb'ing a non-running kernel currently fails because gdb (wrongly) 352 disregards the starting offset for which the kernel is compiled. 353 354