Linux kernel release 2.6.xx

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1         Linux kernel release 2.6.xx2 3 These are the release notes for Linux version 2.6.  Read them carefully,4 as they tell you what this is all about, explain how to install the5 kernel, and what to do if something goes wrong. 6 7 WHAT IS LINUX?8 9   Linux is a Unix clone written from scratch by Linus Torvalds with10   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-fledged14   Unix, including true multitasking, virtual memory, shared libraries,15   demand loading, shared copy-on-write executables, proper memory16   management and TCP/IP networking. 17 18   It is distributed under the GNU General Public License - see the19   accompanying COPYING file for more details. 20 21 ON WHAT HARDWARE DOES IT RUN?22 23   Linux was first developed for 386/486-based PCs.  These days it also24   runs on ARMs, DEC Alphas, SUN Sparcs, M68000 machines (like Atari and25   Amiga), MIPS and PowerPC, and others.26 27 DOCUMENTATION:28 29  - There is a lot of documentation available both in electronic form on30    the Internet and in books, both Linux-specific and pertaining to31    general UNIX questions.  I'd recommend looking into the documentation32    subdirectories on any Linux FTP site for the LDP (Linux Documentation33    Project) books.  This README is not meant to be documentation on the34    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 what39    is contained in each file.  Please read the Changes file, as it40    contains information about the problems, which may result by upgrading41    your kernel.42 43  - The Documentation/DocBook/ subdirectory contains several guides for44    kernel developers and users.  These guides can be rendered in a45    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 49 INSTALLING the kernel:50 51  - If you install the full sources, put the kernel tarball in a52    directory where you have permissions (eg. your home directory) and53    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 (usually60    incomplete) set of kernel headers that are used by the library header61    files.  They should match the library, and not get messed up by62    whatever the kernel-du-jour happens to be.63 64  - You can also upgrade between 2.6.xx releases by patching.  Patches are65    distributed in the traditional gzip and the new bzip2 format.  To66    install by patching, get all the newer patch files, enter the67    top level directory of the kernel source (linux-2.6.xx) and execute:68 69                 gzip -cd ../patch-2.6.xx.gz | patch -p170 71    or72                 bzip2 -dc ../patch-2.6.xx.bz2 | patch -p173 74    (repeat xx for all versions bigger than the version of your current75    source tree, _in_order_) and you should be ok.  You may want to remove76    the backup files (xxx~ or xxx.orig), and make sure that there are no77    failed patches (xxx# or xxx.rej). If there are, either you or me has78    made a mistake.79 80    Alternatively, the script patch-kernel can be used to automate this81    process.  It determines the current kernel version and applies any82    patches found.83 84                 linux/scripts/patch-kernel linux85 86    The first argument in the command above is the location of the87    kernel source.  Patches are applied from the current directory, but88    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 linux93                 make mrproper94 95    You should now have the sources correctly installed.96 97 SOFTWARE REQUIREMENTS98 99    Compiling and running the 2.6.xx kernels requires up-to-date100    versions of various software packages.  Consult101    Documentation/Changes for the minimum version numbers required102    and how to get updates for these packages.  Beware that using103    excessively old versions of these packages can cause indirect104    errors that are very difficult to track down, so don't assume that105    you can just update packages when obvious problems arise during106    build or operation.107 108 BUILD directory for the kernel:109 110    When compiling the kernel all output files will per default be111    stored together with the kernel source code.112    Using the option "make O=output/dir" allow you to specify an alternate113    place for the output files (including .config).114    Example:115      kernel source code:        /usr/src/linux-2.6.N116      build directory:           /home/name/build/kernel117 118    To configure and build the kernel use:119    cd /usr/src/linux-2.6.N120    make O=/home/name/build/kernel menuconfig121    make O=/home/name/build/kernel122    sudo make O=/home/name/build/kernel modules_install install123 124    Please note: If the 'O=output/dir' option is used then it must be125    used for all invocations of make.126 127 CONFIGURING the kernel:128 129    Do not skip this step even if you are only upgrading one minor130    version.  New configuration options are added in each release, and131    odd problems will turn up if the configuration files are not set up132    as expected.  If you want to carry your existing configuration to a133    new version with minimal work, use "make oldconfig", which will134    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 of141                            your existing ./.config file.142    143         NOTES on "make config":144         - having unnecessary drivers will make the kernel bigger, and can145           under some circumstances lead to problems: probing for a146           nonexistent controller card may confuse your other controllers147         - compiling the kernel with "Processor type" set higher than 386148           will result in a kernel that does NOT work on a 386.  The149           kernel will detect this on bootup, and give up.150         - A kernel with math-emulation compiled in will still use the151           coprocessor if one is present: the math emulation will just152           never get used in that case.  The kernel will be slightly larger,153           but will work on different machines regardless of whether they154           have a math coprocessor or not. 155         - the "kernel hacking" configuration details usually result in a156           bigger or slower kernel (or both), and can even make the kernel157           less stable by configuring some routines to actively try to158           break bad code to find kernel problems (kmalloc()).  Thus you159           should probably answer 'n' to the questions for160           "development", "experimental", or "debugging" features.161 162  - Check the top Makefile for further site-dependent configuration163    (default SVGA mode etc). 164 165 COMPILING 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 miscompile169    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 also176    possible to do "make install" if you have lilo installed to suit the177    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 normal180    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', you183    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 release187    contains new code which has not been debugged.  Make sure you keep a188    backup of the modules corresponding to that kernel, as well.  If you189    are installing a new kernel with the same version number as your190    working kernel, make a backup of your modules directory before you191    do a "make modules_install".192 193  - In order to boot your new kernel, you'll need to copy the kernel194    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 a198    bootloader such as LILO, is no longer supported.199 200    If you boot Linux from the hard drive, chances are you use LILO which201    uses the kernel image as specified in the file /etc/lilo.conf.  The202    kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or203    /boot/bzImage.  To use the new kernel, save a copy of the old image204    and copy the new image over the old one.  Then, you MUST RERUN LILO205    to update the loading map!! If you don't, you won't be able to boot206    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 your210    old kernel image (say, /vmlinux.old) in case the new one does not211    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 (or218    alternatively the LILO boot options when appropriate).  No need to219    recompile the kernel to change these parameters. 220 221  - Reboot with the new kernel and enjoy. 222 223 IF SOMETHING GOES WRONG:224 225  - If you have problems that seem to be due to kernel bugs, please check226    the file MAINTAINERS to see if there is a particular person associated227    with the part of the kernel that you are having trouble with. If there228    isn't anyone listed there, then the second best thing is to mail229    them to me (torvalds@osdl.org), and possibly to any other relevant230    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 common234    sense).  If the problem is new, tell me so, and if the problem is235    old, please try to tell me when you first noticed it.236 237  - If the bug results in a message like238 239         unable to handle kernel paging request at address C0000010240         Oops: 0002241         EIP:   0010:XXXXXXXX242         eax: xxxxxxxx   ebx: xxxxxxxx   ecx: xxxxxxxx   edx: xxxxxxxx243         esi: xxxxxxxx   edi: xxxxxxxx   ebp: xxxxxxxx244         ds: xxxx  es: xxxx  fs: xxxx  gs: xxxx245         Pid: xx, process nr: xx246         xx xx xx xx xx xx xx xx xx xx247 248    or similar kernel debugging information on your screen or in your249    system log, please duplicate it *exactly*.  The dump may look250    incomprehensible to you, but it does contain information that may251    help debugging the problem.  The text above the dump is also252    important: it tells something about why the kernel dumped code (in253    the above example it's due to a bad kernel pointer). More information254    on making sense of the dump is in Documentation/oops-tracing.txt255 256  - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump257    as is, otherwise you will have to use the "ksymoops" program to make258    sense of the dump.  This utility can be downloaded from259    ftp://ftp..kernel.org/pub/...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 can263    look up what the EIP value means.  The hex value as such doesn't help264    me or anybody else very much: it will depend on your particular265    kernel setup.  What you should do is take the hex value from the EIP266    line (ignore the "0010:"), and look it up in the kernel namelist to267    see which kernel function contains the offending address.268 269    To find out the kernel function name, you'll need to find the system270    binary associated with the kernel that exhibited the symptom.  This is271    the file 'linux/vmlinux'.  To extract the namelist and match it against272    the EIP from the kernel crash, do:273 274                 nm vmlinux | sort | less275 276    This will give you a list of kernel addresses sorted in ascending277    order, from which it is simple to find the function that contains the278    offending address.  Note that the address given by the kernel279    debugging messages will not necessarily match exactly with the280    function addresses (in fact, that is very unlikely), so you can't281    just 'grep' the list: the list will, however, give you the starting282    point of each kernel function, so by looking for the function that283    has a starting address lower than the one you are searching for but284    is followed by a function with a higher address you will find the one285    you want.  In fact, it may be a good idea to include a bit of286    "context" in your problem report, giving a few lines around the287    interesting one. 288 289    If you for some reason cannot do the above (you have a pre-compiled290    kernel image or similar), telling me as much about your setup as291    possible will help. 292 293  - Alternately, you can use gdb on a running kernel. (read-only; i.e. you294    cannot change values or set break points.) To do this, first compile the295    kernel with -g; edit arch/i386/Makefile appropriately, then do a "make296    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 the300    point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes301    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