1 Linux kernel release 2.6.xx 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 Unix clone written from scratch by Linus Torvalds with 10 assistance from a loosely-knit team of hackers across the Net. 11 It aims towards POSIX compliance. 12 13 It has all the features you would expect in a modern fully-fledged 14 Unix, including true multitasking, virtual memory, shared libraries, 15 demand loading, shared copy-on-write executables, proper memory 16 management and TCP/IP networking. 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 Linux was first developed for 386/486-based PCs. These days it also 24 runs on ARMs, DEC Alphas, SUN Sparcs, M68000 machines (like Atari and 25 Amiga), MIPS and PowerPC, and others. 26 27DOCUMENTATION: 28 29 - There is a lot of documentation available both in electronic form on 30 the Internet and in books, both Linux-specific and pertaining to 31 general UNIX questions. I'd recommend looking into the documentation 32 subdirectories on any Linux FTP site for the LDP (Linux Documentation 33 Project) books. This README is not meant to be documentation on the 34 system: there are much better sources available. 35 36 - There are various README files in the Documentation/ subdirectory: 37 these typically contain kernel-specific installation notes for some 38 drivers for example. See Documentation/00-INDEX for a list of what 39 is contained in each file. Please read the Changes file, as it 40 contains information about the problems, which may result by upgrading 41 your kernel. 42 43 - The Documentation/DocBook/ subdirectory contains several guides for 44 kernel developers and users. These guides can be rendered in a 45 number of formats: PostScript (.ps), PDF, and HTML, among others. 46 After installation, "make psdocs", "make pdfdocs", or "make htmldocs" 47 will render the documentation in the requested format. 48 49INSTALLING the kernel: 50 51 - If you install the full sources, put the kernel tarball in a 52 directory where you have permissions (eg. your home directory) and 53 unpack it: 54 55 gzip -cd linux-2.6.XX.tar.gz | tar xvf - 56 57 Replace "XX" with the version number of the latest kernel. 58 59 Do NOT use the /usr/src/linux area! This area has a (usually 60 incomplete) set of kernel headers that are used by the library header 61 files. They should match the library, and not get messed up by 62 whatever the kernel-du-jour happens to be. 63 64 - You can also upgrade between 2.6.xx releases by patching. Patches are 65 distributed in the traditional gzip and the new bzip2 format. To 66 install by patching, get all the newer patch files, enter the 67 top level directory of the kernel source (linux-2.6.xx) and execute: 68 69 gzip -cd ../patch-2.6.xx.gz | patch -p1 70 71 or 72 bzip2 -dc ../patch-2.6.xx.bz2 | patch -p1 73 74 (repeat xx for all versions bigger than the version of your current 75 source tree, _in_order_) and you should be ok. You may want to remove 76 the backup files (xxx~ or xxx.orig), and make sure that there are no 77 failed patches (xxx# or xxx.rej). If there are, either you or me has 78 made a mistake. 79 80 Alternatively, the script patch-kernel can be used to automate this 81 process. It determines the current kernel version and applies any 82 patches found. 83 84 linux/scripts/patch-kernel linux 85 86 The first argument in the command above is the location of the 87 kernel source. Patches are applied from the current directory, but 88 an alternative directory can be specified as the second argument. 89 90 - Make sure you have no stale .o files and dependencies lying around: 91 92 cd linux 93 make mrproper 94 95 You should now have the sources correctly installed. 96 97SOFTWARE REQUIREMENTS 98 99 Compiling and running the 2.6.xx kernels requires up-to-date 100 versions of various software packages. Consult 101 Documentation/Changes for the minimum version numbers required 102 and how to get updates for these packages. Beware that using 103 excessively old versions of these packages can cause indirect 104 errors that are very difficult to track down, so don't assume that 105 you can just update packages when obvious problems arise during 106 build or operation. 107 108BUILD directory for the kernel: 109 110 When compiling the kernel all output files will per default be 111 stored together with the kernel source code. 112 Using the option "make O=output/dir" allow you to specify an alternate 113 place for the output files (including .config). 114 Example: 115 kernel source code: /usr/src/linux-2.6.N 116 build directory: /home/name/build/kernel 117 118 To configure and build the kernel use: 119 cd /usr/src/linux-2.6.N 120 make O=/home/name/build/kernel menuconfig 121 make O=/home/name/build/kernel 122 sudo make O=/home/name/build/kernel modules_install install 123 124 Please note: If the 'O=output/dir' option is used then it must be 125 used for all invocations of make. 126 127CONFIGURING the kernel: 128 129 Do not skip this step even if you are only upgrading one minor 130 version. New configuration options are added in each release, and 131 odd problems will turn up if the configuration files are not set up 132 as expected. If you want to carry your existing configuration to a 133 new version with minimal work, use "make oldconfig", which will 134 only ask you for the answers to new questions. 135 136 - Alternate configuration commands are: 137 "make menuconfig" Text based color menus, radiolists & dialogs. 138 "make xconfig" X windows (Qt) based configuration tool. 139 "make gconfig" X windows (Gtk) based configuration tool. 140 "make oldconfig" Default all questions based on the contents of 141 your existing ./.config file. 142 143 NOTES on "make config": 144 - having unnecessary drivers will make the kernel bigger, and can 145 under some circumstances lead to problems: probing for a 146 nonexistent controller card may confuse your other controllers 147 - compiling the kernel with "Processor type" set higher than 386 148 will result in a kernel that does NOT work on a 386. The 149 kernel will detect this on bootup, and give up. 150 - A kernel with math-emulation compiled in will still use the 151 coprocessor if one is present: the math emulation will just 152 never get used in that case. The kernel will be slightly larger, 153 but will work on different machines regardless of whether they 154 have a math coprocessor or not. 155 - the "kernel hacking" configuration details usually result in a 156 bigger or slower kernel (or both), and can even make the kernel 157 less stable by configuring some routines to actively try to 158 break bad code to find kernel problems (kmalloc()). Thus you 159 should probably answer 'n' to the questions for 160 "development", "experimental", or "debugging" features. 161 162 - Check the top Makefile for further site-dependent configuration 163 (default SVGA mode etc). 164 165COMPILING the kernel: 166 167 - Make sure you have gcc 2.95.3 available. 168 gcc 2.91.66 (egcs-1.1.2), and gcc 2.7.2.3 are known to miscompile 169 some parts of the kernel, and are *no longer supported*. 170 Also remember to upgrade your binutils package (for as/ld/nm and company) 171 if necessary. For more information, refer to Documentation/Changes. 172 173 Please note that you can still run a.out user programs with this kernel. 174 175 - Do a "make" to create a compressed kernel image. It is also 176 possible to do "make install" if you have lilo installed to suit the 177 kernel makefiles, but you may want to check your particular lilo setup first. 178 179 To do the actual install you have to be root, but none of the normal 180 build should require that. Don't take the name of root in vain. 181 182 - If you configured any of the parts of the kernel as `modules', you 183 will also have to do "make modules_install". 184 185 - Keep a backup kernel handy in case something goes wrong. This is 186 especially true for the development releases, since each new release 187 contains new code which has not been debugged. Make sure you keep a 188 backup of the modules corresponding to that kernel, as well. If you 189 are installing a new kernel with the same version number as your 190 working kernel, make a backup of your modules directory before you 191 do a "make modules_install". 192 193 - In order to boot your new kernel, you'll need to copy the kernel 194 image (e.g. .../linux/arch/i386/boot/bzImage after compilation) 195 to the place where your regular bootable kernel is found. 196 197 - Booting a kernel directly from a floppy without the assistance of a 198 bootloader such as LILO, is no longer supported. 199 200 If you boot Linux from the hard drive, chances are you use LILO which 201 uses the kernel image as specified in the file /etc/lilo.conf. The 202 kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or 203 /boot/bzImage. To use the new kernel, save a copy of the old image 204 and copy the new image over the old one. Then, you MUST RERUN LILO 205 to update the loading map!! If you don't, you won't be able to boot 206 the new kernel image. 207 208 Reinstalling LILO is usually a matter of running /sbin/lilo. 209 You may wish to edit /etc/lilo.conf to specify an entry for your 210 old kernel image (say, /vmlinux.old) in case the new one does not 211 work. See the LILO docs for more information. 212 213 After reinstalling LILO, you should be all set. Shutdown the system, 214 reboot, and enjoy! 215 216 If you ever need to change the default root device, video mode, 217 ramdisk size, etc. in the kernel image, use the 'rdev' program (or 218 alternatively the LILO boot options when appropriate). No need to 219 recompile the kernel to change these parameters. 220 221 - Reboot with the new kernel and enjoy. 222 223IF SOMETHING GOES WRONG: 224 225 - If you have problems that seem to be due to kernel bugs, please check 226 the file MAINTAINERS to see if there is a particular person associated 227 with the part of the kernel that you are having trouble with. If there 228 isn't anyone listed there, then the second best thing is to mail 229 them to me (torvalds@osdl.org), and possibly to any other relevant 230 mailing-list or to the newsgroup. 231 232 - In all bug-reports, *please* tell what kernel you are talking about, 233 how to duplicate the problem, and what your setup is (use your common 234 sense). If the problem is new, tell me so, and if the problem is 235 old, please try to tell me when you first noticed it. 236 237 - If the bug results in a message like 238 239 unable to handle kernel paging request at address C0000010 240 Oops: 0002 241 EIP: 0010:XXXXXXXX 242 eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx 243 esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx 244 ds: xxxx es: xxxx fs: xxxx gs: xxxx 245 Pid: xx, process nr: xx 246 xx xx xx xx xx xx xx xx xx xx 247 248 or similar kernel debugging information on your screen or in your 249 system log, please duplicate it *exactly*. The dump may look 250 incomprehensible to you, but it does contain information that may 251 help debugging the problem. The text above the dump is also 252 important: it tells something about why the kernel dumped code (in 253 the above example it's due to a bad kernel pointer). More information 254 on making sense of the dump is in Documentation/oops-tracing.txt 255 256 - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump 257 as is, otherwise you will have to use the "ksymoops" program to make 258 sense of the dump. This utility can be downloaded from 259 ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops. 260 Alternately you can do the dump lookup by hand: 261 262 - In debugging dumps like the above, it helps enormously if you can 263 look up what the EIP value means. The hex value as such doesn't help 264 me or anybody else very much: it will depend on your particular 265 kernel setup. What you should do is take the hex value from the EIP 266 line (ignore the "0010:"), and look it up in the kernel namelist to 267 see which kernel function contains the offending address. 268 269 To find out the kernel function name, you'll need to find the system 270 binary associated with the kernel that exhibited the symptom. This is 271 the file 'linux/vmlinux'. To extract the namelist and match it against 272 the EIP from the kernel crash, do: 273 274 nm vmlinux | sort | less 275 276 This will give you a list of kernel addresses sorted in ascending 277 order, from which it is simple to find the function that contains the 278 offending address. Note that the address given by the kernel 279 debugging messages will not necessarily match exactly with the 280 function addresses (in fact, that is very unlikely), so you can't 281 just 'grep' the list: the list will, however, give you the starting 282 point of each kernel function, so by looking for the function that 283 has a starting address lower than the one you are searching for but 284 is followed by a function with a higher address you will find the one 285 you want. In fact, it may be a good idea to include a bit of 286 "context" in your problem report, giving a few lines around the 287 interesting one. 288 289 If you for some reason cannot do the above (you have a pre-compiled 290 kernel image or similar), telling me as much about your setup as 291 possible will help. 292 293 - Alternately, you can use gdb on a running kernel. (read-only; i.e. you 294 cannot change values or set break points.) To do this, first compile the 295 kernel with -g; edit arch/i386/Makefile appropriately, then do a "make 296 clean". You'll also need to enable CONFIG_PROC_FS (via "make config"). 297 298 After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore". 299 You can now use all the usual gdb commands. The command to look up the 300 point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes 301 with the EIP value.) 302 303 gdb'ing a non-running kernel currently fails because gdb (wrongly) 304 disregards the starting offset for which the kernel is compiled. 305 306