FreeBSD/Linux Kernel Cross Reference
sys/

	Name	Size	Last modified (GMT)	Description
	Documentation/		2009-10-05 12:56:08
	arch/		2009-10-05 12:53:06
	block/		2009-10-05 12:53:06
	crypto/		2009-10-05 12:53:06
	drivers/		2009-10-05 12:50:55
	firmware/		2009-10-05 12:49:43
	fs/		2009-10-05 12:50:40
	include/		2009-10-05 12:50:17
	init/		2009-10-05 12:50:17
	ipc/		2009-10-05 12:50:16
	kernel/		2009-10-05 12:50:16
	lib/		2009-10-05 12:50:13
	mm/		2009-10-05 12:50:13
	net/		2009-10-05 12:49:58
	samples/		2009-10-05 12:49:45
	scripts/		2009-10-05 12:49:57
	security/		2009-10-05 12:49:56
	sound/		2009-10-05 12:49:45
	tools/		2009-10-05 12:45:56
	usr/		2009-10-05 12:49:45
	virt/		2008-02-17 11:07:38
	COPYING	18693 bytes	2006-12-13 11:48:09
	CREDITS	94031 bytes	2009-10-05 12:43:22
	Kbuild	2430 bytes	2008-12-11 08:29:18
	MAINTAINERS	157864 bytes	2009-10-05 12:43:25
	Makefile	56692 bytes	2009-10-05 12:43:25
	README	17459 bytes	2009-10-05 12:43:25
	REPORTING-BUGS	3371 bytes	2009-10-05 12:43:25

             Linux kernel release 2.6.xx <http://kernel.org/>
     
     These are the release notes for Linux version 2.6.  Read them carefully,
     as they tell you what this is all about, explain how to install the
     kernel, and what to do if something goes wrong. 
     
     WHAT IS LINUX?
     
       Linux is a clone of the operating system Unix, written from scratch by
      Linus Torvalds with assistance from a loosely-knit team of hackers across
      the Net. It aims towards POSIX and Single UNIX Specification compliance.
    
      It has all the features you would expect in a modern fully-fledged Unix,
      including true multitasking, virtual memory, shared libraries, demand
      loading, shared copy-on-write executables, proper memory management,
      and multistack networking including IPv4 and IPv6.
    
      It is distributed under the GNU General Public License - see the
      accompanying COPYING file for more details. 
    
    ON WHAT HARDWARE DOES IT RUN?
    
      Although originally developed first for 32-bit x86-based PCs (386 or higher),
      today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and
      UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell,
      IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS,
      Xtensa, AVR32 and Renesas M32R architectures.
    
      Linux is easily portable to most general-purpose 32- or 64-bit architectures
      as long as they have a paged memory management unit (PMMU) and a port of the
      GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has
      also been ported to a number of architectures without a PMMU, although
      functionality is then obviously somewhat limited.
      Linux has also been ported to itself. You can now run the kernel as a
      userspace application - this is called UserMode Linux (UML).
    
    DOCUMENTATION:
    
     - There is a lot of documentation available both in electronic form on
       the Internet and in books, both Linux-specific and pertaining to
       general UNIX questions.  I'd recommend looking into the documentation
       subdirectories on any Linux FTP site for the LDP (Linux Documentation
       Project) books.  This README is not meant to be documentation on the
       system: there are much better sources available.
    
     - There are various README files in the Documentation/ subdirectory:
       these typically contain kernel-specific installation notes for some 
       drivers for example. See Documentation/00-INDEX for a list of what
       is contained in each file.  Please read the Changes file, as it
       contains information about the problems, which may result by upgrading
       your kernel.
    
     - The Documentation/DocBook/ subdirectory contains several guides for
       kernel developers and users.  These guides can be rendered in a
       number of formats:  PostScript (.ps), PDF, HTML, & man-pages, among others.
       After installation, "make psdocs", "make pdfdocs", "make htmldocs",
       or "make mandocs" will render the documentation in the requested format.
    
    INSTALLING the kernel source:
    
     - If you install the full sources, put the kernel tarball in a
       directory where you have permissions (eg. your home directory) and
       unpack it:
    
                    gzip -cd linux-2.6.XX.tar.gz | tar xvf -
    
       or
                    bzip2 -dc linux-2.6.XX.tar.bz2 | tar xvf -
    
    
       Replace "XX" with the version number of the latest kernel.
    
       Do NOT use the /usr/src/linux area! This area has a (usually
       incomplete) set of kernel headers that are used by the library header
       files.  They should match the library, and not get messed up by
       whatever the kernel-du-jour happens to be.
    
     - You can also upgrade between 2.6.xx releases by patching.  Patches are
       distributed in the traditional gzip and the newer bzip2 format.  To
       install by patching, get all the newer patch files, enter the
       top level directory of the kernel source (linux-2.6.xx) and execute:
    
                    gzip -cd ../patch-2.6.xx.gz | patch -p1
    
       or
                    bzip2 -dc ../patch-2.6.xx.bz2 | patch -p1
    
       (repeat xx for all versions bigger than the version of your current
       source tree, _in_order_) and you should be ok.  You may want to remove
       the backup files (xxx~ or xxx.orig), and make sure that there are no
       failed patches (xxx# or xxx.rej). If there are, either you or me has
       made a mistake.
    
       Unlike patches for the 2.6.x kernels, patches for the 2.6.x.y kernels
       (also known as the -stable kernels) are not incremental but instead apply
       directly to the base 2.6.x kernel.  Please read
       Documentation/applying-patches.txt for more information.
    
       Alternatively, the script patch-kernel can be used to automate this
      process.  It determines the current kernel version and applies any
      patches found.
   
                   linux/scripts/patch-kernel linux
   
      The first argument in the command above is the location of the
      kernel source.  Patches are applied from the current directory, but
      an alternative directory can be specified as the second argument.
   
    - If you are upgrading between releases using the stable series patches
      (for example, patch-2.6.xx.y), note that these "dot-releases" are
      not incremental and must be applied to the 2.6.xx base tree. For
      example, if your base kernel is 2.6.12 and you want to apply the
      2.6.12.3 patch, you do not and indeed must not first apply the
      2.6.12.1 and 2.6.12.2 patches. Similarly, if you are running kernel
      version 2.6.12.2 and want to jump to 2.6.12.3, you must first
      reverse the 2.6.12.2 patch (that is, patch -R) _before_ applying
      the 2.6.12.3 patch.
      You can read more on this in Documentation/applying-patches.txt
   
    - Make sure you have no stale .o files and dependencies lying around:
   
                   cd linux
                   make mrproper
   
      You should now have the sources correctly installed.
   
   SOFTWARE REQUIREMENTS
   
      Compiling and running the 2.6.xx kernels requires up-to-date
      versions of various software packages.  Consult
      Documentation/Changes for the minimum version numbers required
      and how to get updates for these packages.  Beware that using
      excessively old versions of these packages can cause indirect
      errors that are very difficult to track down, so don't assume that
      you can just update packages when obvious problems arise during
      build or operation.
   
   BUILD directory for the kernel:
   
      When compiling the kernel all output files will per default be
      stored together with the kernel source code.
      Using the option "make O=output/dir" allow you to specify an alternate
      place for the output files (including .config).
      Example:
        kernel source code:        /usr/src/linux-2.6.N
        build directory:           /home/name/build/kernel
   
      To configure and build the kernel use:
      cd /usr/src/linux-2.6.N
      make O=/home/name/build/kernel menuconfig
      make O=/home/name/build/kernel
      sudo make O=/home/name/build/kernel modules_install install
   
      Please note: If the 'O=output/dir' option is used then it must be
      used for all invocations of make.
   
   CONFIGURING the kernel:
   
      Do not skip this step even if you are only upgrading one minor
      version.  New configuration options are added in each release, and
      odd problems will turn up if the configuration files are not set up
      as expected.  If you want to carry your existing configuration to a
      new version with minimal work, use "make oldconfig", which will
      only ask you for the answers to new questions.
   
    - Alternate configuration commands are:
           "make config"      Plain text interface.
           "make menuconfig"  Text based color menus, radiolists & dialogs.
           "make xconfig"     X windows (Qt) based configuration tool.
           "make gconfig"     X windows (Gtk) based configuration tool.
           "make oldconfig"   Default all questions based on the contents of
                              your existing ./.config file and asking about
                              new config symbols.
           "make silentoldconfig"
                              Like above, but avoids cluttering the screen
                              with questions already answered.
                              Additionally updates the dependencies.
           "make defconfig"   Create a ./.config file by using the default
                              symbol values from either arch/$ARCH/defconfig
                              or arch/$ARCH/configs/${PLATFORM}_defconfig,
                              depending on the architecture.
           "make ${PLATFORM}_defconfig"
                             Create a ./.config file by using the default
                             symbol values from
                             arch/$ARCH/configs/${PLATFORM}_defconfig.
                             Use "make help" to get a list of all available
                             platforms of your architecture.
           "make allyesconfig"
                              Create a ./.config file by setting symbol
                              values to 'y' as much as possible.
           "make allmodconfig"
                              Create a ./.config file by setting symbol
                              values to 'm' as much as possible.
           "make allnoconfig" Create a ./.config file by setting symbol
                              values to 'n' as much as possible.
           "make randconfig"  Create a ./.config file by setting symbol
                              values to random values.
   
      You can find more information on using the Linux kernel config tools
      in Documentation/kbuild/kconfig.txt.
   
           NOTES on "make config":
           - having unnecessary drivers will make the kernel bigger, and can
             under some circumstances lead to problems: probing for a
             nonexistent controller card may confuse your other controllers
           - compiling the kernel with "Processor type" set higher than 386
             will result in a kernel that does NOT work on a 386.  The
             kernel will detect this on bootup, and give up.
           - A kernel with math-emulation compiled in will still use the
             coprocessor if one is present: the math emulation will just
             never get used in that case.  The kernel will be slightly larger,
             but will work on different machines regardless of whether they
             have a math coprocessor or not. 
           - the "kernel hacking" configuration details usually result in a
             bigger or slower kernel (or both), and can even make the kernel
             less stable by configuring some routines to actively try to
             break bad code to find kernel problems (kmalloc()).  Thus you
             should probably answer 'n' to the questions for
             "development", "experimental", or "debugging" features.
   
   COMPILING the kernel:
   
    - Make sure you have at least gcc 3.2 available.
      For more information, refer to Documentation/Changes.
   
      Please note that you can still run a.out user programs with this kernel.
   
    - Do a "make" to create a compressed kernel image. It is also
      possible to do "make install" if you have lilo installed to suit the
      kernel makefiles, but you may want to check your particular lilo setup first.
   
      To do the actual install you have to be root, but none of the normal
      build should require that. Don't take the name of root in vain.
   
    - If you configured any of the parts of the kernel as `modules', you
      will also have to do "make modules_install".
   
    - Verbose kernel compile/build output:
   
      Normally the kernel build system runs in a fairly quiet mode (but not
      totally silent).  However, sometimes you or other kernel developers need
      to see compile, link, or other commands exactly as they are executed.
      For this, use "verbose" build mode.  This is done by inserting
      "V=1" in the "make" command.  E.g.:
   
           make V=1 all
   
      To have the build system also tell the reason for the rebuild of each
      target, use "V=2".  The default is "V=0".
   
    - Keep a backup kernel handy in case something goes wrong.  This is 
      especially true for the development releases, since each new release
      contains new code which has not been debugged.  Make sure you keep a
      backup of the modules corresponding to that kernel, as well.  If you
      are installing a new kernel with the same version number as your
      working kernel, make a backup of your modules directory before you
      do a "make modules_install".
      Alternatively, before compiling, use the kernel config option
      "LOCALVERSION" to append a unique suffix to the regular kernel version.
      LOCALVERSION can be set in the "General Setup" menu.
   
    - In order to boot your new kernel, you'll need to copy the kernel
      image (e.g. .../linux/arch/i386/boot/bzImage after compilation)
      to the place where your regular bootable kernel is found. 
   
    - Booting a kernel directly from a floppy without the assistance of a
      bootloader such as LILO, is no longer supported.
   
      If you boot Linux from the hard drive, chances are you use LILO which
      uses the kernel image as specified in the file /etc/lilo.conf.  The
      kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
      /boot/bzImage.  To use the new kernel, save a copy of the old image
      and copy the new image over the old one.  Then, you MUST RERUN LILO
      to update the loading map!! If you don't, you won't be able to boot
      the new kernel image.
   
      Reinstalling LILO is usually a matter of running /sbin/lilo. 
      You may wish to edit /etc/lilo.conf to specify an entry for your
      old kernel image (say, /vmlinux.old) in case the new one does not
      work.  See the LILO docs for more information. 
   
      After reinstalling LILO, you should be all set.  Shutdown the system,
      reboot, and enjoy!
   
      If you ever need to change the default root device, video mode,
      ramdisk size, etc.  in the kernel image, use the 'rdev' program (or
      alternatively the LILO boot options when appropriate).  No need to
      recompile the kernel to change these parameters. 
   
    - Reboot with the new kernel and enjoy. 
   
   IF SOMETHING GOES WRONG:
   
    - If you have problems that seem to be due to kernel bugs, please check
      the file MAINTAINERS to see if there is a particular person associated
      with the part of the kernel that you are having trouble with. If there
      isn't anyone listed there, then the second best thing is to mail
      them to me (torvalds@linux-foundation.org), and possibly to any other
      relevant mailing-list or to the newsgroup.
   
    - In all bug-reports, *please* tell what kernel you are talking about,
      how to duplicate the problem, and what your setup is (use your common
      sense).  If the problem is new, tell me so, and if the problem is
      old, please try to tell me when you first noticed it.
   
    - If the bug results in a message like
   
           unable to handle kernel paging request at address C0000010
           Oops: 0002
           EIP:   0010:XXXXXXXX
           eax: xxxxxxxx   ebx: xxxxxxxx   ecx: xxxxxxxx   edx: xxxxxxxx
           esi: xxxxxxxx   edi: xxxxxxxx   ebp: xxxxxxxx
           ds: xxxx  es: xxxx  fs: xxxx  gs: xxxx
           Pid: xx, process nr: xx
           xx xx xx xx xx xx xx xx xx xx
   
      or similar kernel debugging information on your screen or in your
      system log, please duplicate it *exactly*.  The dump may look
      incomprehensible to you, but it does contain information that may
      help debugging the problem.  The text above the dump is also
      important: it tells something about why the kernel dumped code (in
      the above example it's due to a bad kernel pointer). More information
      on making sense of the dump is in Documentation/oops-tracing.txt
   
    - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump
      as is, otherwise you will have to use the "ksymoops" program to make
      sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred).
      This utility can be downloaded from
      ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ .
      Alternately you can do the dump lookup by hand:
   
    - In debugging dumps like the above, it helps enormously if you can
      look up what the EIP value means.  The hex value as such doesn't help
      me or anybody else very much: it will depend on your particular
      kernel setup.  What you should do is take the hex value from the EIP
      line (ignore the "0010:"), and look it up in the kernel namelist to
      see which kernel function contains the offending address.
   
      To find out the kernel function name, you'll need to find the system
      binary associated with the kernel that exhibited the symptom.  This is
      the file 'linux/vmlinux'.  To extract the namelist and match it against
      the EIP from the kernel crash, do:
   
                   nm vmlinux | sort | less
   
      This will give you a list of kernel addresses sorted in ascending
      order, from which it is simple to find the function that contains the
      offending address.  Note that the address given by the kernel
      debugging messages will not necessarily match exactly with the
      function addresses (in fact, that is very unlikely), so you can't
      just 'grep' the list: the list will, however, give you the starting
      point of each kernel function, so by looking for the function that
      has a starting address lower than the one you are searching for but
      is followed by a function with a higher address you will find the one
      you want.  In fact, it may be a good idea to include a bit of
      "context" in your problem report, giving a few lines around the
      interesting one. 
   
      If you for some reason cannot do the above (you have a pre-compiled
      kernel image or similar), telling me as much about your setup as
      possible will help.  Please read the REPORTING-BUGS document for details.
   
    - Alternately, you can use gdb on a running kernel. (read-only; i.e. you
      cannot change values or set break points.) To do this, first compile the
      kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
      clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
   
      After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
      You can now use all the usual gdb commands. The command to look up the
      point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
      with the EIP value.)
   
      gdb'ing a non-running kernel currently fails because gdb (wrongly)
      disregards the starting offset for which the kernel is compiled.