271 lines
12 KiB
Plaintext
271 lines
12 KiB
Plaintext
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Linux kernel release 2.0.xx
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These are the release notes for linux version 2.0. 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 DEC Alphas, SUN Sparcs, M68000 machines (like Atari and Amiga),
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MIPS and PowerPC.
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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's in the kernel 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.
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INSTALLING the kernel:
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- If you install the full sources, do a
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cd /usr/src
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gzip -cd linux-2.0.XX.tar.gz | tar xfv -
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to get it all put in place. Replace "XX" with the version number of the
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latest kernel.
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- You can also upgrade between 2.0.xx releases by patching. Each
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patch that is released for 2.0.xx contains only bugfixes. No
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new features will be added to the Linux kernel until the 2.1.xx
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development effort begins. To install by patching, get all the
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newer patch files and do
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cd /usr/src
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gzip -cd patchXX.gz | patch -p0
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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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cd /usr/src
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linux/scripts/patch-kernel
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The default directory for the kernel source is /usr/src/linux, but
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can be specified as the first argument. Patches are applied from
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the current directory, but an alternative directory can be specified
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as the second argument.
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- make sure your /usr/include/asm, /usr/include/linux, and /usr/include/scsi
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directories are just symlinks to the kernel sources:
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cd /usr/include
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rm -rf asm linux scsi
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ln -s /usr/src/linux/include/asm-i386 asm
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ln -s /usr/src/linux/include/linux linux
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ln -s /usr/src/linux/include/scsi scsi
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- make sure you have no stale .o files and dependencies lying around:
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cd /usr/src/linux
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make mrproper
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You should now have the sources correctly installed.
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CONFIGURING the kernel:
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- do a "make config" to configure the basic kernel. "make config"
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needs bash to work: it will search for bash in $BASH, /bin/bash and
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/bin/sh (in that order), so hopefully one of those is correct.
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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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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 a "production"
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kernel.
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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-2.6.3 or newer available. It seems older gcc
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versions can have problems compiling newer versions of linux. If you
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upgrade your compiler, remember to get the new binutils package too
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(for as/ld/nm and company).
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- do a "make zImage" to create a compressed kernel image. If you want
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to make a bootdisk (without root filesystem or lilo), insert a floppy
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in your A: drive, and do a "make zdisk". It is also possible to do
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"make zlilo" 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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- if your kernel is too large for "make zImage", use "make bzImage"
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instead.
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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.
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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 /usr/src/linux/arch/i386/boot/zImage 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 "cp
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/usr/src/linux/arch/i386/boot/zImage /dev/fd0" to make a bootable
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floppy. Note that as of Linux 2.0.0, a kernel copied to a 720k
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double-density 3.5" floppy disk no longer boots. In this case,
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it is highly recommended that you install LILO on your
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double-density bootfloppy or switch to high-density floppies.
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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, or /zImage, or /etc/zImage.
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To use the new kernel, copy the new image over the old one (save a
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backup of the original!). Then, you MUST RERUN LILO to update the
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loading map!! If you don't, you won't be able to boot the new kernel
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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 (Linus.Torvalds@Helsinki.FI), 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. Find
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the C++ sources under the scripts/ directory to avoid having to do
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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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