Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/README

Diff markup

Differences between /README (Version 4.10) and /README (Version 4.9)


  1 Linux kernel                                   !!   1         Linux kernel release 4.x <http://kernel.org/>
  2 ============                                   << 
  3                                                     2 
  4 This file was moved to Documentation/admin-gui !!   3 These are the release notes for Linux version 4.  Read them carefully,
                                                   >>   4 as they tell you what this is all about, explain how to install the
                                                   >>   5 kernel, and what to do if something goes wrong.
  5                                                     6 
  6 Please notice that there are several guides fo !!   7 WHAT IS LINUX?
  7 These guides can be rendered in a number of fo << 
  8                                                     8 
  9 In order to build the documentation, use ``mak !!   9   Linux is a clone of the operating system Unix, written from scratch by
 10 ``make pdfdocs``.                              !!  10   Linus Torvalds with assistance from a loosely-knit team of hackers across
                                                   >>  11   the Net. It aims towards POSIX and Single UNIX Specification compliance.
 11                                                    12 
 12 There are various text files in the Documentat !!  13   It has all the features you would expect in a modern fully-fledged Unix,
 13 several of them using the Restructured Text ma !!  14   including true multitasking, virtual memory, shared libraries, demand
 14 See Documentation/00-INDEX for a list of what  !!  15   loading, shared copy-on-write executables, proper memory management,
                                                   >>  16   and multistack networking including IPv4 and IPv6.
                                                   >>  17 
                                                   >>  18   It is distributed under the GNU General Public License - see the
                                                   >>  19   accompanying COPYING file for more details.
                                                   >>  20 
                                                   >>  21 ON WHAT HARDWARE DOES IT RUN?
                                                   >>  22 
                                                   >>  23   Although originally developed first for 32-bit x86-based PCs (386 or higher),
                                                   >>  24   today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and
                                                   >>  25   UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell,
                                                   >>  26   IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS,
                                                   >>  27   Xtensa, Tilera TILE, AVR32, ARC and Renesas M32R architectures.
                                                   >>  28 
                                                   >>  29   Linux is easily portable to most general-purpose 32- or 64-bit architectures
                                                   >>  30   as long as they have a paged memory management unit (PMMU) and a port of the
                                                   >>  31   GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has
                                                   >>  32   also been ported to a number of architectures without a PMMU, although
                                                   >>  33   functionality is then obviously somewhat limited.
                                                   >>  34   Linux has also been ported to itself. You can now run the kernel as a
                                                   >>  35   userspace application - this is called UserMode Linux (UML).
                                                   >>  36 
                                                   >>  37 DOCUMENTATION:
                                                   >>  38 
                                                   >>  39  - There is a lot of documentation available both in electronic form on
                                                   >>  40    the Internet and in books, both Linux-specific and pertaining to
                                                   >>  41    general UNIX questions.  I'd recommend looking into the documentation
                                                   >>  42    subdirectories on any Linux FTP site for the LDP (Linux Documentation
                                                   >>  43    Project) books.  This README is not meant to be documentation on the
                                                   >>  44    system: there are much better sources available.
                                                   >>  45 
                                                   >>  46  - There are various README files in the Documentation/ subdirectory:
                                                   >>  47    these typically contain kernel-specific installation notes for some
                                                   >>  48    drivers for example. See Documentation/00-INDEX for a list of what
                                                   >>  49    is contained in each file.  Please read the Changes file, as it
                                                   >>  50    contains information about the problems, which may result by upgrading
                                                   >>  51    your kernel.
                                                   >>  52 
                                                   >>  53  - The Documentation/DocBook/ subdirectory contains several guides for
                                                   >>  54    kernel developers and users.  These guides can be rendered in a
                                                   >>  55    number of formats:  PostScript (.ps), PDF, HTML, & man-pages, among others.
                                                   >>  56    After installation, "make psdocs", "make pdfdocs", "make htmldocs",
                                                   >>  57    or "make mandocs" will render the documentation in the requested format.
                                                   >>  58 
                                                   >>  59 INSTALLING the kernel source:
                                                   >>  60 
                                                   >>  61  - If you install the full sources, put the kernel tarball in a
                                                   >>  62    directory where you have permissions (e.g. your home directory) and
                                                   >>  63    unpack it:
                                                   >>  64 
                                                   >>  65      xz -cd linux-4.X.tar.xz | tar xvf -
                                                   >>  66 
                                                   >>  67    Replace "X" with the version number of the latest kernel.
                                                   >>  68 
                                                   >>  69    Do NOT use the /usr/src/linux area! This area has a (usually
                                                   >>  70    incomplete) set of kernel headers that are used by the library header
                                                   >>  71    files.  They should match the library, and not get messed up by
                                                   >>  72    whatever the kernel-du-jour happens to be.
                                                   >>  73 
                                                   >>  74  - You can also upgrade between 4.x releases by patching.  Patches are
                                                   >>  75    distributed in the xz format.  To install by patching, get all the
                                                   >>  76    newer patch files, enter the top level directory of the kernel source
                                                   >>  77    (linux-4.X) and execute:
                                                   >>  78 
                                                   >>  79      xz -cd ../patch-4.x.xz | patch -p1
                                                   >>  80 
                                                   >>  81    Replace "x" for all versions bigger than the version "X" of your current
                                                   >>  82    source tree, _in_order_, and you should be ok.  You may want to remove
                                                   >>  83    the backup files (some-file-name~ or some-file-name.orig), and make sure
                                                   >>  84    that there are no failed patches (some-file-name# or some-file-name.rej).
                                                   >>  85    If there are, either you or I have made a mistake.
                                                   >>  86 
                                                   >>  87    Unlike patches for the 4.x kernels, patches for the 4.x.y kernels
                                                   >>  88    (also known as the -stable kernels) are not incremental but instead apply
                                                   >>  89    directly to the base 4.x kernel.  For example, if your base kernel is 4.0
                                                   >>  90    and you want to apply the 4.0.3 patch, you must not first apply the 4.0.1
                                                   >>  91    and 4.0.2 patches. Similarly, if you are running kernel version 4.0.2 and
                                                   >>  92    want to jump to 4.0.3, you must first reverse the 4.0.2 patch (that is,
                                                   >>  93    patch -R) _before_ applying the 4.0.3 patch. You can read more on this in
                                                   >>  94    Documentation/applying-patches.txt
                                                   >>  95 
                                                   >>  96    Alternatively, the script patch-kernel can be used to automate this
                                                   >>  97    process.  It determines the current kernel version and applies any
                                                   >>  98    patches found.
                                                   >>  99 
                                                   >> 100      linux/scripts/patch-kernel linux
                                                   >> 101 
                                                   >> 102    The first argument in the command above is the location of the
                                                   >> 103    kernel source.  Patches are applied from the current directory, but
                                                   >> 104    an alternative directory can be specified as the second argument.
                                                   >> 105 
                                                   >> 106  - Make sure you have no stale .o files and dependencies lying around:
                                                   >> 107 
                                                   >> 108      cd linux
                                                   >> 109      make mrproper
                                                   >> 110 
                                                   >> 111    You should now have the sources correctly installed.
                                                   >> 112 
                                                   >> 113 SOFTWARE REQUIREMENTS
                                                   >> 114 
                                                   >> 115    Compiling and running the 4.x kernels requires up-to-date
                                                   >> 116    versions of various software packages.  Consult
                                                   >> 117    Documentation/Changes for the minimum version numbers required
                                                   >> 118    and how to get updates for these packages.  Beware that using
                                                   >> 119    excessively old versions of these packages can cause indirect
                                                   >> 120    errors that are very difficult to track down, so don't assume that
                                                   >> 121    you can just update packages when obvious problems arise during
                                                   >> 122    build or operation.
                                                   >> 123 
                                                   >> 124 BUILD directory for the kernel:
                                                   >> 125 
                                                   >> 126    When compiling the kernel, all output files will per default be
                                                   >> 127    stored together with the kernel source code.
                                                   >> 128    Using the option "make O=output/dir" allows you to specify an alternate
                                                   >> 129    place for the output files (including .config).
                                                   >> 130    Example:
                                                   >> 131 
                                                   >> 132      kernel source code: /usr/src/linux-4.X
                                                   >> 133      build directory:    /home/name/build/kernel
                                                   >> 134 
                                                   >> 135    To configure and build the kernel, use:
                                                   >> 136 
                                                   >> 137      cd /usr/src/linux-4.X
                                                   >> 138      make O=/home/name/build/kernel menuconfig
                                                   >> 139      make O=/home/name/build/kernel
                                                   >> 140      sudo make O=/home/name/build/kernel modules_install install
                                                   >> 141 
                                                   >> 142    Please note: If the 'O=output/dir' option is used, then it must be
                                                   >> 143    used for all invocations of make.
                                                   >> 144 
                                                   >> 145 CONFIGURING the kernel:
                                                   >> 146 
                                                   >> 147    Do not skip this step even if you are only upgrading one minor
                                                   >> 148    version.  New configuration options are added in each release, and
                                                   >> 149    odd problems will turn up if the configuration files are not set up
                                                   >> 150    as expected.  If you want to carry your existing configuration to a
                                                   >> 151    new version with minimal work, use "make oldconfig", which will
                                                   >> 152    only ask you for the answers to new questions.
                                                   >> 153 
                                                   >> 154  - Alternative configuration commands are:
                                                   >> 155 
                                                   >> 156      "make config"      Plain text interface.
                                                   >> 157 
                                                   >> 158      "make menuconfig"  Text based color menus, radiolists & dialogs.
                                                   >> 159 
                                                   >> 160      "make nconfig"     Enhanced text based color menus.
                                                   >> 161 
                                                   >> 162      "make xconfig"     Qt based configuration tool.
                                                   >> 163 
                                                   >> 164      "make gconfig"     GTK+ based configuration tool.
                                                   >> 165 
                                                   >> 166      "make oldconfig"   Default all questions based on the contents of
                                                   >> 167                         your existing ./.config file and asking about
                                                   >> 168                         new config symbols.
                                                   >> 169 
                                                   >> 170      "make silentoldconfig"
                                                   >> 171                         Like above, but avoids cluttering the screen
                                                   >> 172                         with questions already answered.
                                                   >> 173                         Additionally updates the dependencies.
                                                   >> 174 
                                                   >> 175      "make olddefconfig"
                                                   >> 176                         Like above, but sets new symbols to their default
                                                   >> 177                         values without prompting.
                                                   >> 178 
                                                   >> 179      "make defconfig"   Create a ./.config file by using the default
                                                   >> 180                         symbol values from either arch/$ARCH/defconfig
                                                   >> 181                         or arch/$ARCH/configs/${PLATFORM}_defconfig,
                                                   >> 182                         depending on the architecture.
                                                   >> 183 
                                                   >> 184      "make ${PLATFORM}_defconfig"
                                                   >> 185                         Create a ./.config file by using the default
                                                   >> 186                         symbol values from
                                                   >> 187                         arch/$ARCH/configs/${PLATFORM}_defconfig.
                                                   >> 188                         Use "make help" to get a list of all available
                                                   >> 189                         platforms of your architecture.
                                                   >> 190 
                                                   >> 191      "make allyesconfig"
                                                   >> 192                         Create a ./.config file by setting symbol
                                                   >> 193                         values to 'y' as much as possible.
                                                   >> 194 
                                                   >> 195      "make allmodconfig"
                                                   >> 196                         Create a ./.config file by setting symbol
                                                   >> 197                         values to 'm' as much as possible.
                                                   >> 198 
                                                   >> 199      "make allnoconfig" Create a ./.config file by setting symbol
                                                   >> 200                         values to 'n' as much as possible.
                                                   >> 201 
                                                   >> 202      "make randconfig"  Create a ./.config file by setting symbol
                                                   >> 203                         values to random values.
                                                   >> 204 
                                                   >> 205      "make localmodconfig" Create a config based on current config and
                                                   >> 206                            loaded modules (lsmod). Disables any module
                                                   >> 207                            option that is not needed for the loaded modules.
                                                   >> 208 
                                                   >> 209                            To create a localmodconfig for another machine,
                                                   >> 210                            store the lsmod of that machine into a file
                                                   >> 211                            and pass it in as a LSMOD parameter.
                                                   >> 212 
                                                   >> 213                    target$ lsmod > /tmp/mylsmod
                                                   >> 214                    target$ scp /tmp/mylsmod host:/tmp
                                                   >> 215 
                                                   >> 216                    host$ make LSMOD=/tmp/mylsmod localmodconfig
                                                   >> 217 
                                                   >> 218                            The above also works when cross compiling.
                                                   >> 219 
                                                   >> 220      "make localyesconfig" Similar to localmodconfig, except it will convert
                                                   >> 221                            all module options to built in (=y) options.
                                                   >> 222 
                                                   >> 223    You can find more information on using the Linux kernel config tools
                                                   >> 224    in Documentation/kbuild/kconfig.txt.
                                                   >> 225 
                                                   >> 226  - NOTES on "make config":
                                                   >> 227 
                                                   >> 228     - Having unnecessary drivers will make the kernel bigger, and can
                                                   >> 229       under some circumstances lead to problems: probing for a
                                                   >> 230       nonexistent controller card may confuse your other controllers
                                                   >> 231 
                                                   >> 232     - A kernel with math-emulation compiled in will still use the
                                                   >> 233       coprocessor if one is present: the math emulation will just
                                                   >> 234       never get used in that case.  The kernel will be slightly larger,
                                                   >> 235       but will work on different machines regardless of whether they
                                                   >> 236       have a math coprocessor or not.
                                                   >> 237 
                                                   >> 238     - The "kernel hacking" configuration details usually result in a
                                                   >> 239       bigger or slower kernel (or both), and can even make the kernel
                                                   >> 240       less stable by configuring some routines to actively try to
                                                   >> 241       break bad code to find kernel problems (kmalloc()).  Thus you
                                                   >> 242       should probably answer 'n' to the questions for "development",
                                                   >> 243       "experimental", or "debugging" features.
                                                   >> 244 
                                                   >> 245 COMPILING the kernel:
                                                   >> 246 
                                                   >> 247  - Make sure you have at least gcc 3.2 available.
                                                   >> 248    For more information, refer to Documentation/Changes.
                                                   >> 249 
                                                   >> 250    Please note that you can still run a.out user programs with this kernel.
                                                   >> 251 
                                                   >> 252  - Do a "make" to create a compressed kernel image. It is also
                                                   >> 253    possible to do "make install" if you have lilo installed to suit the
                                                   >> 254    kernel makefiles, but you may want to check your particular lilo setup first.
                                                   >> 255 
                                                   >> 256    To do the actual install, you have to be root, but none of the normal
                                                   >> 257    build should require that. Don't take the name of root in vain.
                                                   >> 258 
                                                   >> 259  - If you configured any of the parts of the kernel as `modules', you
                                                   >> 260    will also have to do "make modules_install".
                                                   >> 261 
                                                   >> 262  - Verbose kernel compile/build output:
                                                   >> 263 
                                                   >> 264    Normally, the kernel build system runs in a fairly quiet mode (but not
                                                   >> 265    totally silent).  However, sometimes you or other kernel developers need
                                                   >> 266    to see compile, link, or other commands exactly as they are executed.
                                                   >> 267    For this, use "verbose" build mode.  This is done by passing
                                                   >> 268    "V=1" to the "make" command, e.g.
                                                   >> 269 
                                                   >> 270      make V=1 all
                                                   >> 271 
                                                   >> 272    To have the build system also tell the reason for the rebuild of each
                                                   >> 273    target, use "V=2".  The default is "V=0".
                                                   >> 274 
                                                   >> 275  - Keep a backup kernel handy in case something goes wrong.  This is
                                                   >> 276    especially true for the development releases, since each new release
                                                   >> 277    contains new code which has not been debugged.  Make sure you keep a
                                                   >> 278    backup of the modules corresponding to that kernel, as well.  If you
                                                   >> 279    are installing a new kernel with the same version number as your
                                                   >> 280    working kernel, make a backup of your modules directory before you
                                                   >> 281    do a "make modules_install".
                                                   >> 282 
                                                   >> 283    Alternatively, before compiling, use the kernel config option
                                                   >> 284    "LOCALVERSION" to append a unique suffix to the regular kernel version.
                                                   >> 285    LOCALVERSION can be set in the "General Setup" menu.
                                                   >> 286 
                                                   >> 287  - In order to boot your new kernel, you'll need to copy the kernel
                                                   >> 288    image (e.g. .../linux/arch/x86/boot/bzImage after compilation)
                                                   >> 289    to the place where your regular bootable kernel is found.
                                                   >> 290 
                                                   >> 291  - Booting a kernel directly from a floppy without the assistance of a
                                                   >> 292    bootloader such as LILO, is no longer supported.
                                                   >> 293 
                                                   >> 294    If you boot Linux from the hard drive, chances are you use LILO, which
                                                   >> 295    uses the kernel image as specified in the file /etc/lilo.conf.  The
                                                   >> 296    kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
                                                   >> 297    /boot/bzImage.  To use the new kernel, save a copy of the old image
                                                   >> 298    and copy the new image over the old one.  Then, you MUST RERUN LILO
                                                   >> 299    to update the loading map! If you don't, you won't be able to boot
                                                   >> 300    the new kernel image.
                                                   >> 301 
                                                   >> 302    Reinstalling LILO is usually a matter of running /sbin/lilo.
                                                   >> 303    You may wish to edit /etc/lilo.conf to specify an entry for your
                                                   >> 304    old kernel image (say, /vmlinux.old) in case the new one does not
                                                   >> 305    work.  See the LILO docs for more information.
                                                   >> 306 
                                                   >> 307    After reinstalling LILO, you should be all set.  Shutdown the system,
                                                   >> 308    reboot, and enjoy!
                                                   >> 309 
                                                   >> 310    If you ever need to change the default root device, video mode,
                                                   >> 311    ramdisk size, etc.  in the kernel image, use the 'rdev' program (or
                                                   >> 312    alternatively the LILO boot options when appropriate).  No need to
                                                   >> 313    recompile the kernel to change these parameters.
                                                   >> 314 
                                                   >> 315  - Reboot with the new kernel and enjoy.
                                                   >> 316 
                                                   >> 317 IF SOMETHING GOES WRONG:
                                                   >> 318 
                                                   >> 319  - If you have problems that seem to be due to kernel bugs, please check
                                                   >> 320    the file MAINTAINERS to see if there is a particular person associated
                                                   >> 321    with the part of the kernel that you are having trouble with. If there
                                                   >> 322    isn't anyone listed there, then the second best thing is to mail
                                                   >> 323    them to me (torvalds@linux-foundation.org), and possibly to any other
                                                   >> 324    relevant mailing-list or to the newsgroup.
                                                   >> 325 
                                                   >> 326  - In all bug-reports, *please* tell what kernel you are talking about,
                                                   >> 327    how to duplicate the problem, and what your setup is (use your common
                                                   >> 328    sense).  If the problem is new, tell me so, and if the problem is
                                                   >> 329    old, please try to tell me when you first noticed it.
                                                   >> 330 
                                                   >> 331  - If the bug results in a message like
                                                   >> 332 
                                                   >> 333      unable to handle kernel paging request at address C0000010
                                                   >> 334      Oops: 0002
                                                   >> 335      EIP:   0010:XXXXXXXX
                                                   >> 336      eax: xxxxxxxx   ebx: xxxxxxxx   ecx: xxxxxxxx   edx: xxxxxxxx
                                                   >> 337      esi: xxxxxxxx   edi: xxxxxxxx   ebp: xxxxxxxx
                                                   >> 338      ds: xxxx  es: xxxx  fs: xxxx  gs: xxxx
                                                   >> 339      Pid: xx, process nr: xx
                                                   >> 340      xx xx xx xx xx xx xx xx xx xx
                                                   >> 341 
                                                   >> 342    or similar kernel debugging information on your screen or in your
                                                   >> 343    system log, please duplicate it *exactly*.  The dump may look
                                                   >> 344    incomprehensible to you, but it does contain information that may
                                                   >> 345    help debugging the problem.  The text above the dump is also
                                                   >> 346    important: it tells something about why the kernel dumped code (in
                                                   >> 347    the above example, it's due to a bad kernel pointer). More information
                                                   >> 348    on making sense of the dump is in Documentation/oops-tracing.txt
                                                   >> 349 
                                                   >> 350  - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump
                                                   >> 351    as is, otherwise you will have to use the "ksymoops" program to make
                                                   >> 352    sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred).
                                                   >> 353    This utility can be downloaded from
                                                   >> 354    ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ .
                                                   >> 355    Alternatively, you can do the dump lookup by hand:
                                                   >> 356 
                                                   >> 357  - In debugging dumps like the above, it helps enormously if you can
                                                   >> 358    look up what the EIP value means.  The hex value as such doesn't help
                                                   >> 359    me or anybody else very much: it will depend on your particular
                                                   >> 360    kernel setup.  What you should do is take the hex value from the EIP
                                                   >> 361    line (ignore the "0010:"), and look it up in the kernel namelist to
                                                   >> 362    see which kernel function contains the offending address.
                                                   >> 363 
                                                   >> 364    To find out the kernel function name, you'll need to find the system
                                                   >> 365    binary associated with the kernel that exhibited the symptom.  This is
                                                   >> 366    the file 'linux/vmlinux'.  To extract the namelist and match it against
                                                   >> 367    the EIP from the kernel crash, do:
                                                   >> 368 
                                                   >> 369      nm vmlinux | sort | less
                                                   >> 370 
                                                   >> 371    This will give you a list of kernel addresses sorted in ascending
                                                   >> 372    order, from which it is simple to find the function that contains the
                                                   >> 373    offending address.  Note that the address given by the kernel
                                                   >> 374    debugging messages will not necessarily match exactly with the
                                                   >> 375    function addresses (in fact, that is very unlikely), so you can't
                                                   >> 376    just 'grep' the list: the list will, however, give you the starting
                                                   >> 377    point of each kernel function, so by looking for the function that
                                                   >> 378    has a starting address lower than the one you are searching for but
                                                   >> 379    is followed by a function with a higher address you will find the one
                                                   >> 380    you want.  In fact, it may be a good idea to include a bit of
                                                   >> 381    "context" in your problem report, giving a few lines around the
                                                   >> 382    interesting one.
                                                   >> 383 
                                                   >> 384    If you for some reason cannot do the above (you have a pre-compiled
                                                   >> 385    kernel image or similar), telling me as much about your setup as
                                                   >> 386    possible will help.  Please read the REPORTING-BUGS document for details.
                                                   >> 387 
                                                   >> 388  - Alternatively, you can use gdb on a running kernel. (read-only; i.e. you
                                                   >> 389    cannot change values or set break points.) To do this, first compile the
                                                   >> 390    kernel with -g; edit arch/x86/Makefile appropriately, then do a "make
                                                   >> 391    clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
                                                   >> 392 
                                                   >> 393    After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
                                                   >> 394    You can now use all the usual gdb commands. The command to look up the
                                                   >> 395    point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
                                                   >> 396    with the EIP value.)
                                                   >> 397 
                                                   >> 398    gdb'ing a non-running kernel currently fails because gdb (wrongly)
                                                   >> 399    disregards the starting offset for which the kernel is compiled.
 15                                                   400 
 16 Please read the Documentation/process/changes. << 
 17 requirements for building and running the kern << 
 18 the problems which may result by upgrading you << 
                                                      

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us