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 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 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. 169 "make silentoldconfig" 170 Like above, but avoids cluttering the screen 171 with questions already answered. 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 192COMPILING the kernel: 193 194 - Make sure you have at least gcc 3.2 available. 195 For more information, refer to Documentation/Changes. 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". 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. 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 250IF 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. 332 333