linux/README
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6 61"/a>        Linux kernel release 3.x <http://kernel.org/>"/a>.6 62"/a>.6 63"/a>These are the release notes for Linux vers >
 3.  Read them carefully,.6 64"/a>as they tell you what this is all about, explain how to install the.6 65"/a>kernel, and what to do if something goes wrong. .6 66"/a>.6 67"/a>WHAT IS LINUX?.6 68"/a>.6 69"/a>  Linux is a clone of the operating system Unix, written from scratch by.6 n vaa>  Linus Tor v3ds with assistance from a loosely-knit team of hackers across.6 11"/a>  the Net. It aims towards POSIX and Single UNIX Specifica  >
 compliance..6 12"/a>.6 13"/a>  It has all the features you would expect in a modern fully-fledged Unix,.6 14"/a>  including true multitasking, virtual memory, shared libraries, demand.6 15"/a>  loading, shared copy-on-write executables, proper memory management,.6 16"/a>  and multistack networking including IPv4 and IPv6..6 17"/a>.6 18"/a>  It is distributed under the GNU General Public License - see the.6 19"/a>  accompanying COPYING file for more details. .6 20"/a>.6 21"/a>ON WHAT HARDWARE DOES IT RUN?.6 22"/a>.6 23"/a>  Although originally developed first for 32-bit x86-based PCs (386 or higher),.6 24"/a>  today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and.6 25"/a>  UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell,.6 26"/a>  IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS,.6 27"/a>  Xtensa, Tilera TILE, AVR32 and Renesas M32R architectures..6 28"/a>.6 29"/a>  Linux is easily portable to most general-purpose 32- or 64-bit architectures.6 3 vaa>  as long as they have a paged memory management unit (PMMU) and a port of the.6 31"/a>  GNU C compiler (gcc) (part of The GNU Compiler Collect >
, GCC). Linux has.6 32vaa>  also been ported to a number of architectures without a PMMU, although.6 33"/a>  funct >
ality is then obviously somewhat limited..6 34"/a>  Linux has also been ported to itself. You can now run the kernel as a.6 35"/a>  userspace applica  >
 - this is called UserMode Linux (UML)..6 36"/a>.6 37"/a>DOCUMENTATION:.6 38"/a>.6 39"/a> - There is a lot of documenta  >
 available both in electronic form on.6 4 vaa>   the Internet and in books, both Linux-specific and pertaining to.6 41"/a>   general UNIX ques  >
s.  I'd recommend looking into the documenta  >
.6 42vaa>   subdirectories on any Linux FTP site for the LDP (Linux Documenta  >
.6 43"/a>   Project) books.  This README is not meant to be documenta  >
 on the.6 44vaa>   system: there are much better sources available..6 45"/a>.6 46"/a> - There are various README files in the Documenta  >
/ subdirectory:.6 47vaa>   these typically contain kernel-specific installa  >
 notes for some .6 48"/a>   drivers for example. See Documenta  >
/00-INDEX for a list of what.6 49"/a>   is contained in each file.  Please read the Changes file, as it.6 5 vaa>   contains informa  >
 about the problems, which may result by upgrading.6 51"/a>   your kernel..6 52"/a>.6 53"/a> - The Documenta  >
/DocBook/ subdirectory contains several guides for.6 54vaa>   kernel developers and users.  These guides can be rendered in a.6 55"/a>   number of forma s:  PostScript (.ps), PDF, HTML, & man-pages, among others..6 56"/a>   After installa  >
, "make psdocs", "make pdfdocs", "make htmldocs",.6 57vaa>   or "make mandocs" will render the documenta  >
 in the reques ed forma ..6 58"/a>.6 59"/a>INSTALLING the kernel source:.6 60"/a>.6 61"/a> - If you install the full sources, put the kernel tarball in a.6 62vaa>   directory where you have permiss >
s (eg. your home directory) and.6 63"/a>   unpack it:.6 64"/a>.6 65"/a>     gzip -cd linux-3.X.tar.gz | tar xvf -.6 66"/a>.6 67vaa>   or.6 68"/a>.6 69"/a>     bzip2 -dc linux-3.X.tar.bz2 | tar xvf -.6 70"/a>.6 71"/a>   Replace "X" with the vers >
 number of the la es  kernel..6 72"/a>.6 73"/a>   Do NOT use the /usr/src/linux area! This area has a (usually.6 74vaa>   incomplete) set of kernel headers that are used by the library header.6 75"/a>   files.  They should match the library, and not get messed up by.6 76"/a>   whatever the kernel-du-jour happens to be..6 77"/a>.6 78"/a> - You can also upgrade between 3.x releases by patching.  Patches are.6 79vaa>   distributed in the tradit >
al gzip and the newer bzip2 forma .  To.6 80vaa>   install by patching, get all the newer patch files, enter the.6 81"/a>   top level directory of the kernel source (linux-3.X) and execute:.6 82"/a>.6 83"/a>     gzip -cd ../patch-3.x.gz | patch -p1.6 84"/a>.6 85vaa>   or.6 86"/a>.6 87"/a>     bzip2 -dc ../patch-3.x.bz2 | patch -p1.6 88"/a>.6 89"/a>   Replace "x" for all vers >
s bigger than the vers >
 "X" of your current.6 90vaa>   source tree, _in_order_, and you should be ok.  You may want to remove.6 91"/a>   the backup files (some-file-nam1~ or some-file-nam1.orig), and make sure.6 92"/a>   that there are no failed patches (some-file-nam1# or some-file-nam1.rej)..6 93"/a>   If there are, either you or I have made a mistake..6 94"/a>.6 95vaa>   Unlike patches for the 3.x kernels, patches for the 3.x.y kernels.6 96"/a>   (also known as the -stable kernels) are not incremental but instead apply.6 97vaa>   directly to the base 3.x kernel.  For example, if your base kernel is 3.0.6 98"/a>   and you want to apply the 3.0.3 patch, you mus  not first apply the 3.0.1.6 99"/a>   and 3.0.2 patches. Similarly, if you are running kernel vers >
 3.0.2 and.6100"/a>   want to jump to 3.0.3, you mus  first reverse the 3.0.2 patch (that is,.6101"/a>   patch -R) _before_ applying the 3.0.3 patch. You can read more on this i
.6102"/a>   Documenta  >
/applying-patches.txt.6103"/a>.6104vaa>   Alterna  vely, the script patch-kernel can be used to automa e this.6105vaa>   process.  It determines the current kernel vers >
 and applies any.6106"/a>   patches found..6107"/a>.6108"/a>     linux/scripts/patch-kernel linux.6109"/a>.61n vaa>   The first argument in the command above is the loca  >
 of the.6111"/a>   kernel source.  Patches are applied from the current directory, but.6112"/a>   an alterna  ve directory can be specified as the second argument..6113"/a>.6114"/a> - Make sure you have no stale .o files and dependencies lying around:.6115"/a>.6116"/a>     cd linux.6117"/a>     make mrproper.6118"/a>.6119"/a>   You should now have the sources correctly installed..6120"/a>.6121"/a>SOFTWARE REQUIREMENTS.6122"/a>.6123"/a>   Compiling and running the 3.x kernels requires up-to-da e.6124"/a>   vers >
s of various software packages.  Consult.6125"/a>   Documenta  >
/Changes for the minimum vers >
 numbers required.6126"/a>   and how to get upda es for these packages.  Beware that using.6127"/a>   excess vely old vers >
s of these packages can cause indirect.6128"/a>   errors that are very difficult to track down, so don't assume that.6129"/a>   you can jus  upda e packages when obvious problems arise during.613 vaa>   build or operation..6131"/a>.6132vaa>BUILD directory for the kernel:.6133"/a>.6134"/a>   When compiling the kernel, all output files will per default be.6135"/a>   stored together with the kernel source code..6136"/a>   Using the 
	  >
 "make O=output/dir" allow you to specify an alterna e.6137"/a>   place for the output files (including .config)..6138"/a>   Example:.6139"/a>.614 vaa>     kernel source code: /usr/src/linux-3.X.6141"/a>     build directory:    /home/nam1/build/kernel.6142"/a>.6143"/a>   To configure and build the kernel, use:.6144"/a>.6145"/a>     cd /usr/src/linux-3.X.6146"/a>     make O=/home/nam1/build/kernel menuconfig.6147"/a>     make O=/home/nam1/build/kernel.6148"/a>     sudo make O=/home/nam1/build/kernel modules_install install.6149"/a>.615 vaa>   Please note: If the 'O=output/dir' 
	  >
 is used, then it mus  be.6151"/a>   used for all invoca  >
s of make..6152"/a>.6153"/a>CONFIGURING the kernel:.6154"/a>.6155"/a>   Do not skip this step even if you are only upgrading one minor.6156"/a>   vers >
.  New configura  >
 op  >
s are added in each release, and.6157vaa>   odd problems will turn up if the configura  >
 files are not set up.6158"/a>   as expected.  If you want to carry your existing configura  >
 to a.6159"/a>   new vers >
 with minimal work, use "make oldconfig", which will.616 vaa>   only ask you for the answers to new ques  >
s..6161"/a>.6162vaa> - Alterna  ve configura  >
 commands are:.6163"/a>.6164"/a>     "make config"      Plain text interface..6165"/a>.6166"/a>     "make menuconfig"  Text based color menus, radiolists & dialogs..6167"/a>.6168"/a>     "make nconfig"     Enhanced text based color menus..6169"/a>.6170"/a>     "make xconfig"     X windows (Qt) based configura  >
 tool..6171"/a>.6172"/a>     "make gconfig"     X windows (Gtk) based configura  >
 tool..6173"/a>.6174"/a>     "make oldconfig"   Default all ques  >
s based on the contents of.6175"/a>                        your existing ./.config file and asking about.6176"/a>                        new config symbols..6177"/a>.6178"/a>     "make silentoldconfig".6179"/a>                        Like above, but avoids cluttering the scree
.6180"/a>                        with ques  >
s already answered..6181"/a>                        Addit >
ally upda es the dependencies..6182"/a>.6183"/a>     "make olddefconfig".6184"/a>                        Like above, but sets new symbols to their default.6185"/a>                         v3.1s without prompting..6186"/a>.6187"/a>     "make defconfig"   Create a ./.config file by using the default.6188"/a>                        symbol  v3.1s from either arch/$ARCH/defconfig.6189"/a>                        or arch/$ARCH/configs/${PLATFORM}_defconfig,.6190"/a>                        depending on the architecture..6191"/a>.6192"/a>     "make ${PLATFORM}_defconfig".6193"/a>                        Create a ./.config file by using the default.6194"/a>                        symbol  v3.1s from.6195"/a>                        arch/$ARCH/configs/${PLATFORM}_defconfig..6196"/a>                        Use "make help" to get a list of all available.6197"/a>                        platforms of your architecture..6198"/a>.6199"/a>     "make allyesconfig".6200"/a>                        Create a ./.config file by setting symbol.6201"/a>                         v3.1s to 'y' as much as possible..6202"/a>.6203"/a>     "make allmodconfig".6204"/a>                        Create a ./.config file by setting symbol.6205"/a>                         v3.1s to 'm' as much as possible..6206"/a>.6207"/a>     "make allnoconfig" Create a ./.config file by setting symbol.6208"/a>                         v3.1s to 'n' as much as possible..6209"/a>.6210"/a>     "make randconfig"  Create a ./.config file by setting symbol.6211"/a>                         v3.1s to random  v3.1s..6212"/a>.6213"/a>     "make localmodconfig" Create a config based on current config and.6214"/a>                           loaded modules (lsmod). Disables any module.6215"/a>                           
	  >
 that is not needed for the loaded modules..6216"/a>.6217"/a>                           To create a localmodconfig for another machine,.6218"/a>                           store the lsmod of that machine into a file.6219"/a>                           and pass it in as a LSMOD param1ter..6220"/a>.6221"/a>                   target$ lsmod > /tmp/mylsmod.6222"/a>                   target$ scp /tmp/mylsmod host:/tmp.6223"/a>.6224"/a>                   host$ make LSMOD=/tmp/mylsmod localmodconfig.6225"/a>.6226"/a>                           The above also works when cross compiling..6227"/a>.6228"/a>     "make localyesconfig" Similar to localmodconfig, except it will convert.6229"/a>                           all module op  >
s to built in (=y) op  >
s..6230"/a>.6231"/a>   You can find more informa  >
 >
 using the Linux kernel config tools.6232vaa>   in Documenta  >
/kbuild/kconfig.txt..6233"/a>.6234"/a> - NOTES >
 "make config":.6235"/a>.6236"/a>    - Having unnecessary drivers will make the kernel bigger, and can.6237"/a>      under some circumstances lead to problems: probing for a.6238"/a>      nonexistent controller card may confuse your other controllers.6239"/a>.624 vaa>    - Compiling the kernel with "Processor type" set higher than 386.6241"/a>      will result in a kernel that does NOT work on a 386.  The.6242"/a>      kernel will detect this on bootup, and g ve up..6243"/a>.6244vaa>    - A kernel with ma h-emula  >
 compiled in will still use the.6245"/a>      coprocessor if one is present: the ma h emula  >
 will jus .6246"/a>      never get used in that case.  The kernel will be slightly larger,.6247"/a>      but will work on different machines regardless of whether they.6248"/a>      have a ma h coprocessor or not..6249"/a>.625 vaa>    - The "kernel hacking" configura  >
 details usually result in a.6251"/a>      bigger or slower kernel (or both), and can even make the kernel.6252"/a>      less stable by configuring some routines to ac  vely try to.6253"/a>      break bad code to find kernel problems (kmalloc()).  Thus you.6254"/a>      should probably answer 'n' to the ques  >
s for "development",.6255"/a>      "experimental", or "debugging" features..6256"/a>.6257vaa>COMPILING the kernel:.6258"/a>.6259"/a> - Make sure you have at least gcc 3.2 available..626 vaa>   For more informa  >
, refer to Documenta  >
/Changes..6261"/a>.6262vaa>   Please note that you can still run a.out user programs with this kernel..6263"/a>.6264"/a> - Do a "make" to create a compressed kernel image. It is also.6265"/a>   possible to do "make install" if you have lilo installed to suit the.6266"/a>   kernel makefiles, but you may want to check your particular lilo setup first..6267"/a>.6268"/a>   To do the actual install, you have to be root, but none of the normal.6269"/a>   build should require that. Don't take the nam1 of root in vain..6270"/a>.6271"/a> - If you configured any of the parts of the kernel as `modules', you.6272"/a>   will also have to do "make modules_install"..6273"/a>.6274"/a> - Verbose kernel compile/build output:.6275"/a>.6276"/a>   Normally, the kernel build system runs in a fairly quiet mode (but no .6277vaa>   totally silent).  However, sometimes you or other kernel developers need.6278"/a>   to see compile, link, or other commands exactly as they are executed..6279"/a>   For this, use "verbose" build mode.  This is done by inserting.6280"/a>   "V=1" in the "make" command.  E.g.:.6281"/a>.6282"/a>     make V=1 all.6283"/a>.6284"/a>   To have the build system also tell the reas>
 for the rebuild of each.6285"/a>   target, use "V=2".  The default is "V=0"..6286"/a>.6287"/a> - Keep a backup kernel handy in case something goes wrong.  This is .6288"/a>   especially true for the development releases, since each new release.6289"/a>   contains new code which has not been debugged.  Make sure you keep a.6290"/a>   backup of the modules corresponding to that kernel, as well.  If you.6291"/a>   are installing a new kernel with the sam1 vers >
 number as your.6292"/a>   working kernel, make a backup of your modules directory before you.6293"/a>   do a "make modules_install"..6294"/a>.6295"/a>   Alterna  vely, before compiling, use the kernel config op  >
.6296"/a>   "LOCALVERSION" to append a unique suffix to the regular kernel vers >
..6297"/a>   LOCALVERSION can be set in the "General Setup" menu..6298"/a>.6299"/a> - In order to boot your new kernel, you'll need to copy the kernel.6300"/a>   image (e.g. .../linux/arch/i386/boot/bzImage after compila  >
).6301"/a>   to the place where your regular bootable kernel is found. .6302"/a>.6303"/a> - Booting a kernel directly from a floppy without the assistance of a.6304"/a>   bootloader such as LILO, is no longer supported..6305"/a>.6306"/a>   If you boot Linux from the hard drive, chances are you use LILO, which.6307"/a>   uses the kernel image as specified in the file /etc/lilo.conf.  The.6308"/a>   kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or.6309"/a>   /boot/bzImage.  To use the new kernel, save a copy of the old image.6310"/a>   and copy the new image over the old one.  Then, you MUST RERUN LILO.6311"/a>   to upda e the loading map!! If you don't, you won't be able to boot.6312"/a>   the new kernel image..6313"/a>.6314"/a>   Reinstalling LILO is usually a ma ter of running /sbin/lilo. .6315"/a>   You may wish to edit /etc/lilo.conf to specify an entry for your.6316"/a>   old kernel image (say, /vmlinux.old) in case the new one does no .6317"/a>   work.  See the LILO docs for more informa  >
. .6318"/a>.6319"/a>   After reinstalling LILO, you should be all set.  Shutdown the system,.6320"/a>   reboot, and enjoy!.6321"/a>.6322"/a>   If you ever need to change the default root device, video mode,.6323"/a>   ramdisk size, etc.  in the kernel image, use the 'rdev' program (or.6324"/a>   alterna  vely the LILO boot op  >
s when appropria e).  No need to.6325"/a>   recompile the kernel to change these param1ters. .6326"/a>.6327"/a> - Reboot with the new kernel and enjoy. .6328"/a>.6329"/a>IF SOMETHING GOES WRONG:.6330"/a>.6331"/a> - If you have problems that seem to be due to kernel bugs, please check.6332"/a>   the file MAINTAINERS to see if there is a particular person associa ed.6333"/a>   with the part of the kernel that you are having trouble with. If there.6334"/a>   isn't anyone listed there, then the second bes  thing is to mail.6335"/a>   them to me (torvalds@linux-founda  >
.org), and possibly to any other.6336"/a>   relevant mailing-list or to the newsgroup..6337"/a>.6338"/a> - In all bug-reports, *please* tell what kernel you are talking about,.6339"/a>   how to duplica e the problem, and what your setup is (use your comm>
.634 vaa>   sense).  If the problem is new, tell me so, and if the problem is.6341"/a>   old, please try to tell me when you first no iced it..6342"/a>.6343"/a> - If the bug results in a message like.6344"/a>.6345"/a>     unable to handle kernel paging reques  at address C0000010.6346"/a>     Oops: 0002.6347"/a>     EIP:   0010:XXXXXXXX.6348"/a>     eax: xxxxxxxx   ebx: xxxxxxxx   ecx: xxxxxxxx   edx: xxxxxxxx.6349"/a>     esi: xxxxxxxx   edi: xxxxxxxx   ebp: xxxxxxxx.635 vaa>     ds: xxxx  es: xxxx  fs: xxxx  gs: xxxx.6351"/a>     Pid: xx, process nr: xx.6352"/a>     xx xx xx xx xx xx xx xx xx xx.6353"/a>.6354"/a>   or similar kernel debugging informa  >
 >
 your scree
 or in your.6355"/a>   system log, please duplica e it *exactly*.  The dump may look.6356"/a>   incomprehensible to you, but it does contain informa  >
 that may.6357vaa>   help debugging the problem.  The text above the dump is also.6358"/a>   important: it tells something about why the kernel dumped code (i
.6359"/a>   the above example, it's due to a bad kernel pointer). More informa  >
.636 vaa>   on making sense of the dump is in Documenta  >
/oops-tracing.txt.6361"/a>.6362vaa> - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump.6363"/a>   as is, otherwise you will have to use the "ksymoops" program to make.6364"/a>   sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred)..6365"/a>   This utility can be downloaded from.6366"/a>   ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ ..6367vaa>   Alterna  vely, you can do the dump lookup by hand:.6368"/a>.6369"/a> - In debugging dumps like the above, it helps enormously if you can.6370"/a>   look up what the EIP  v3.1 means.  The hex  v3.1 as such doesn't help.6371"/a>   m1 or anybody else very much: it will depend >
 your particular.6372"/a>   kernel setup.  What you should do is take the hex  v3.1 from the EIP.6373"/a>   line (ignore the "0010:"), and look it up in the kernel nam1list to.6374"/a>   see which kernel func  >
 contains the offending address..6375"/a>.6376"/a>   To find out the kernel func  >
 nam1, you'll need to find the system.6377vaa>   binary associa ed with the kernel that exhibited the symptom.  This is.6378"/a>   the file 'linux/vmlinux'.  To extract the nam1list and match it against.6379"/a>   the EIP from the kernel crash, do:.6380"/a>.6381"/a>     nm vmlinux | sort | less.6382"/a>.6383"/a>   This will g ve you a list of kernel addresses sorted in ascending.6384"/a>   order, from which it is simple to find the func  >
 that contains the.6385"/a>   offending address.  Note that the address g ven by the kernel.6386"/a>   debugging messages will not necessarily match exactly with the.6387"/a>   func  >
 addresses (i
 fact, that is very unlikely), so you can't.6388"/a>   jus  'grep' the list: the list will, however, g ve you the starting.6389"/a>   point of each kernel func  >
, so by looking for the func  >
 that.6390"/a>   has a starting address lower than the one you are searching for but.6391"/a>   is followed by a func  >
 with a higher address you will find the one.6392"/a>   you want.  I
 fact, it may be a good idea to include a bit of.6393"/a>   "context" in your problem report, g ving a few lines around the.6394"/a>   interesting one. .6395"/a>.6396"/a>   If you for some reas>
 cannot do the above (you have a pre-compiled.6397"/a>   kernel image or similar), telling me as much about your setup as.6398"/a>   possible will help.  Please read the REPORTING-BUGS document for details..6399"/a>.6400"/a> - Alterna  vely, you can use gdb on a running kernel. (read-only; i.e. you.6401"/a>   cannot change  v3.1s or set break points.) To do this, first compile the.6402"/a>   kernel with -g; edit arch/i386/Makefile appropria ely, then do a "make.6403"/a>   clean". You'll also need to enable CONFIG_PROC_FS (via "make config")..6404"/a>.6405"/a>   After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore"..6406"/a>   You can now use all the usual gdb commands. The command to look up the.6407"/a>   point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes.6408"/a>   with the EIP  v3.1.).6409"/a>.6410"/a>   gdb'ing a non-running kernel currently fails because gdb (wrongly).6411"/a>   disregards the starting offset for which the kernel is compiled..6412"/a>.6413"/a>
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