Linux kernel release 2.0.xx These are the release notes for linux version 2.0. 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 Unix clone written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX 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 TCP/IP networking. It is distributed under the GNU General Public License - see the accompanying COPYING file for more details. ON WHAT HARDWARE DOES IT RUN? Linux was first developed for 386/486-based PCs. These days it also runs on DEC Alphas, SUN Sparcs, M68000 machines (like Atari and Amiga), MIPS and PowerPC. 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's in the kernel 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. INSTALLING the kernel: - If you install the full sources, do a cd /usr/src gzip -cd linux-2.0.XX.tar.gz | tar xfv - to get it all put in place. Replace "XX" with the version number of the latest kernel. - You can also upgrade between 2.0.xx releases by patching. Each patch that is released for 2.0.xx contains only bugfixes. No new features will be added to the Linux kernel until the 2.1.xx development effort begins. To install by patching, get all the newer patch files and do cd /usr/src gzip -cd patchXX.gz | patch -p0 (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. Alternatively, the script patch-kernel can be used to automate this process. It determines the current kernel version and applies any patches found. cd /usr/src linux/scripts/patch-kernel The default directory for the kernel source is /usr/src/linux, but can be specified as the first argument. Patches are applied from the current directory, but an alternative directory can be specified as the second argument. - make sure your /usr/include/asm, /usr/include/linux, and /usr/include/scsi directories are just symlinks to the kernel sources: cd /usr/include rm -rf asm linux scsi ln -s /usr/src/linux/include/asm-i386 asm ln -s /usr/src/linux/include/linux linux ln -s /usr/src/linux/include/scsi scsi - make sure you have no stale .o files and dependencies lying around: cd /usr/src/linux make mrproper You should now have the sources correctly installed. CONFIGURING the kernel: - do a "make config" to configure the basic kernel. "make config" needs bash to work: it will search for bash in $BASH, /bin/bash and /bin/sh (in that order), so hopefully one of those is correct. - Alternate configuration commands are: "make menuconfig" Text based color menus, radiolists & dialogs. "make xconfig" X windows based configuration tool. 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 a "production" kernel. - Check the top Makefile for further site-dependent configuration (default SVGA mode etc). - Finally, do a "make dep" to set up all the dependencies correctly. COMPILING the kernel: - make sure you have gcc-2.6.3 or newer available. It seems older gcc versions can have problems compiling newer versions of linux. If you upgrade your compiler, remember to get the new binutils package too (for as/ld/nm and company). - do a "make zImage" to create a compressed kernel image. If you want to make a bootdisk (without root filesystem or lilo), insert a floppy in your A: drive, and do a "make zdisk". It is also possible to do "make zlilo" if you have lilo installed to suit the kernel makefiles, but you may want to check your particular lilo setup first. - if your kernel is too large for "make zImage", use "make bzImage" instead. - if you configured any of the parts of the kernel as `modules', you will have to do "make modules" followed by "make modules_install". Read Documentation/modules.txt for more information. For example, an explanation of how to use the modules is included there. - 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. - In order to boot your new kernel, you'll need to copy the kernel image (found in /usr/src/linux/arch/i386/boot/zImage after compilation) to the place where your regular bootable kernel is found. For some, this is on a floppy disk, in which case you can "cp /usr/src/linux/arch/i386/boot/zImage /dev/fd0" to make a bootable floppy. Note that as of Linux 2.0.0, a kernel copied to a 720k double-density 3.5" floppy disk no longer boots. In this case, it is highly recommended that you install LILO on your double-density bootfloppy or switch to high-density floppies. 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, or /zImage, or /etc/zImage. To use the new kernel, copy the new image over the old one (save a backup of the original!). 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 (Linus.Torvalds@Helsinki.FI), and possibly to any other relevant mailing-list or to the newsgroup. The mailing-lists are useful especially for SCSI and NETworking problems, as I can't test either of those personally anyway. - 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 - You can use the "ksymoops" program to make sense of the dump. Find the C++ sources under the scripts/ directory to avoid having to 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. - 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.