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phoenix |
Linux kernel release 2.4.xx
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These are the release notes for Linux version 2.4. Read them carefully,
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as they tell you what this is all about, explain how to install the
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kernel, and what to do if something goes wrong.
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WHAT IS LINUX?
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Linux is a Unix clone written from scratch by Linus Torvalds with
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assistance from a loosely-knit team of hackers across the Net.
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It aims towards POSIX compliance.
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It has all the features you would expect in a modern fully-fledged
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Unix, including true multitasking, virtual memory, shared libraries,
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demand loading, shared copy-on-write executables, proper memory
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management and TCP/IP networking.
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It is distributed under the GNU General Public License - see the
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accompanying COPYING file for more details.
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ON WHAT HARDWARE DOES IT RUN?
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Linux was first developed for 386/486-based PCs. These days it also
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runs on ARMs, DEC Alphas, SUN Sparcs, M68000 machines (like Atari and
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Amiga), MIPS and PowerPC, and others.
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DOCUMENTATION:
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- There is a lot of documentation available both in electronic form on
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the Internet and in books, both Linux-specific and pertaining to
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general UNIX questions. I'd recommend looking into the documentation
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subdirectories on any Linux FTP site for the LDP (Linux Documentation
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Project) books. This README is not meant to be documentation on the
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system: there are much better sources available.
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- There are various README files in the Documentation/ subdirectory:
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these typically contain kernel-specific installation notes for some
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drivers for example. See ./Documentation/00-INDEX for a list of what
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is contained in each file. Please read the Changes file, as it
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contains information about the problems, which may result by upgrading
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your kernel.
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- The Documentation/DocBook/ subdirectory contains several guides for
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kernel developers and users. These guides can be rendered in a
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number of formats: PostScript (.ps), PDF, and HTML, among others.
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After installation, "make psdocs", "make pdfdocs", or "make htmldocs"
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will render the documentation in the requested format.
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INSTALLING the kernel:
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- If you install the full sources, put the kernel tarball in a
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directory where you have permissions (eg. your home directory) and
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unpack it:
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gzip -cd linux-2.4.XX.tar.gz | tar xvf -
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Replace "XX" with the version number of the latest kernel.
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Do NOT use the /usr/src/linux area! This area has a (usually
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incomplete) set of kernel headers that are used by the library header
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files. They should match the library, and not get messed up by
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whatever the kernel-du-jour happens to be.
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- You can also upgrade between 2.4.xx releases by patching. Patches are
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distributed in the traditional gzip and the new bzip2 format. To
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install by patching, get all the newer patch files, enter the
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top level directory of the kernel source (linux-2.4.xx) and execute:
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gzip -cd ../patch-2.4.xx.gz | patch -p1
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or
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bzip2 -dc ../patch-2.4.xx.bz2 | patch -p1
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(repeat xx for all versions bigger than the version of your current
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source tree, _in_order_) and you should be ok. You may want to remove
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the backup files (xxx~ or xxx.orig), and make sure that there are no
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failed patches (xxx# or xxx.rej). If there are, either you or me has
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made a mistake.
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Alternatively, the script patch-kernel can be used to automate this
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process. It determines the current kernel version and applies any
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patches found.
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linux/scripts/patch-kernel linux
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The first argument in the command above is the location of the
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kernel source. Patches are applied from the current directory, but
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an alternative directory can be specified as the second argument.
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- Make sure you have no stale .o files and dependencies lying around:
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cd linux
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make mrproper
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You should now have the sources correctly installed.
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SOFTWARE REQUIREMENTS
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Compiling and running the 2.4.xx kernels requires up-to-date
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versions of various software packages. Consult
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./Documentation/Changes for the minimum version numbers required
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and how to get updates for these packages. Beware that using
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excessively old versions of these packages can cause indirect
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errors that are very difficult to track down, so don't assume that
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you can just update packages when obvious problems arise during
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build or operation.
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CONFIGURING the kernel:
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- Do a "make config" to configure the basic kernel. "make config" needs
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bash to work: it will search for bash in $BASH, /bin/bash and /bin/sh
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(in that order), so one of those must be correct for it to work.
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Do not skip this step even if you are only upgrading one minor
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version. New configuration options are added in each release, and
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odd problems will turn up if the configuration files are not set up
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as expected. If you want to carry your existing configuration to a
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new version with minimal work, use "make oldconfig", which will
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only ask you for the answers to new questions.
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- Alternate configuration commands are:
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"make menuconfig" Text based color menus, radiolists & dialogs.
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"make xconfig" X windows based configuration tool.
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"make oldconfig" Default all questions based on the contents of
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your existing ./.config file.
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NOTES on "make config":
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- having unnecessary drivers will make the kernel bigger, and can
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under some circumstances lead to problems: probing for a
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nonexistent controller card may confuse your other controllers
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- compiling the kernel with "Processor type" set higher than 386
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will result in a kernel that does NOT work on a 386. The
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kernel will detect this on bootup, and give up.
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- A kernel with math-emulation compiled in will still use the
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coprocessor if one is present: the math emulation will just
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never get used in that case. The kernel will be slightly larger,
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but will work on different machines regardless of whether they
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have a math coprocessor or not.
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- the "kernel hacking" configuration details usually result in a
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bigger or slower kernel (or both), and can even make the kernel
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less stable by configuring some routines to actively try to
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break bad code to find kernel problems (kmalloc()). Thus you
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should probably answer 'n' to the questions for
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"development", "experimental", or "debugging" features.
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- Check the top Makefile for further site-dependent configuration
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(default SVGA mode etc).
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- Finally, do a "make dep" to set up all the dependencies correctly.
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COMPILING the kernel:
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- Make sure you have gcc 2.95.3 available. gcc 2.91.66 (egcs-1.1.2) may
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also work but is not as safe, and *gcc 2.7.2.3 is no longer supported*.
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Also remember to upgrade your binutils package (for as/ld/nm and company)
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if necessary. For more information, refer to ./Documentation/Changes.
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Please note that you can still run a.out user programs with this kernel.
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- Do a "make bzImage" to create a compressed kernel image. If you want
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to make a boot disk (without root filesystem or LILO), insert a floppy
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in your A: drive, and do a "make bzdisk". It is also possible to do
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"make install" if you have lilo installed to suit the kernel makefiles,
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but you may want to check your particular lilo setup first.
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To do the actual install you have to be root, but none of the normal
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build should require that. Don't take the name of root in vain.
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- In the unlikely event that your system cannot boot bzImage kernels you
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can still compile your kernel as zImage. However, since zImage support
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will be removed at some point in the future in favor of bzImage we
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encourage people having problems with booting bzImage kernels to report
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these, with detailed hardware configuration information, to the
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linux-kernel mailing list and to H. Peter Anvin .
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- If you configured any of the parts of the kernel as `modules', you
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will have to do "make modules" followed by "make modules_install".
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Read Documentation/modules.txt for more information. For example,
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an explanation of how to use the modules is included there.
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- Keep a backup kernel handy in case something goes wrong. This is
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especially true for the development releases, since each new release
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contains new code which has not been debugged. Make sure you keep a
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backup of the modules corresponding to that kernel, as well. If you
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are installing a new kernel with the same version number as your
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working kernel, make a backup of your modules directory before you
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do a "make modules_install".
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- In order to boot your new kernel, you'll need to copy the kernel
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image (found in .../linux/arch/i386/boot/bzImage after compilation)
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to the place where your regular bootable kernel is found.
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For some, this is on a floppy disk, in which case you can copy the
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kernel bzImage file to /dev/fd0 to make a bootable floppy.
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If you boot Linux from the hard drive, chances are you use LILO which
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uses the kernel image as specified in the file /etc/lilo.conf. The
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kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
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/boot/bzImage. To use the new kernel, save a copy of the old image
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and copy the new image over the old one. Then, you MUST RERUN LILO
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to update the loading map!! If you don't, you won't be able to boot
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the new kernel image.
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Reinstalling LILO is usually a matter of running /sbin/lilo.
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You may wish to edit /etc/lilo.conf to specify an entry for your
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old kernel image (say, /vmlinux.old) in case the new one does not
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work. See the LILO docs for more information.
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After reinstalling LILO, you should be all set. Shutdown the system,
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reboot, and enjoy!
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If you ever need to change the default root device, video mode,
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ramdisk size, etc. in the kernel image, use the 'rdev' program (or
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alternatively the LILO boot options when appropriate). No need to
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recompile the kernel to change these parameters.
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- Reboot with the new kernel and enjoy.
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IF SOMETHING GOES WRONG:
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- If you have problems that seem to be due to kernel bugs, please check
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the file MAINTAINERS to see if there is a particular person associated
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with the part of the kernel that you are having trouble with. If there
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isn't anyone listed there, then the second best thing is to mail
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them to me (torvalds@transmeta.com), and possibly to any other
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relevant mailing-list or to the newsgroup. The mailing-lists are
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useful especially for SCSI and networking problems, as I can't test
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either of those personally anyway.
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- In all bug-reports, *please* tell what kernel you are talking about,
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how to duplicate the problem, and what your setup is (use your common
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sense). If the problem is new, tell me so, and if the problem is
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old, please try to tell me when you first noticed it.
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- If the bug results in a message like
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unable to handle kernel paging request at address C0000010
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Oops: 0002
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EIP: 0010:XXXXXXXX
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eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
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esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
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ds: xxxx es: xxxx fs: xxxx gs: xxxx
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Pid: xx, process nr: xx
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xx xx xx xx xx xx xx xx xx xx
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or similar kernel debugging information on your screen or in your
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system log, please duplicate it *exactly*. The dump may look
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incomprehensible to you, but it does contain information that may
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help debugging the problem. The text above the dump is also
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important: it tells something about why the kernel dumped code (in
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the above example it's due to a bad kernel pointer). More information
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on making sense of the dump is in Documentation/oops-tracing.txt
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- You can use the "ksymoops" program to make sense of the dump. This
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utility can be downloaded from
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ftp://ftp..kernel.org/pub/linux/utils/kernel/ksymoops.
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Alternately you can do the dump lookup by hand:
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- In debugging dumps like the above, it helps enormously if you can
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look up what the EIP value means. The hex value as such doesn't help
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me or anybody else very much: it will depend on your particular
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kernel setup. What you should do is take the hex value from the EIP
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line (ignore the "0010:"), and look it up in the kernel namelist to
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see which kernel function contains the offending address.
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To find out the kernel function name, you'll need to find the system
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binary associated with the kernel that exhibited the symptom. This is
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the file 'linux/vmlinux'. To extract the namelist and match it against
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the EIP from the kernel crash, do:
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nm vmlinux | sort | less
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This will give you a list of kernel addresses sorted in ascending
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order, from which it is simple to find the function that contains the
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offending address. Note that the address given by the kernel
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debugging messages will not necessarily match exactly with the
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function addresses (in fact, that is very unlikely), so you can't
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just 'grep' the list: the list will, however, give you the starting
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point of each kernel function, so by looking for the function that
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has a starting address lower than the one you are searching for but
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is followed by a function with a higher address you will find the one
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you want. In fact, it may be a good idea to include a bit of
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"context" in your problem report, giving a few lines around the
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interesting one.
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If you for some reason cannot do the above (you have a pre-compiled
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kernel image or similar), telling me as much about your setup as
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possible will help.
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- Alternately, you can use gdb on a running kernel. (read-only; i.e. you
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cannot change values or set break points.) To do this, first compile the
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kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
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clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
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After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
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You can now use all the usual gdb commands. The command to look up the
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point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
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with the EIP value.)
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gdb'ing a non-running kernel currently fails because gdb (wrongly)
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disregards the starting offset for which the kernel is compiled.
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