README

What is Linux-DSM?

  Based On Linux, Linux-DSM supports GiantVM by distributed vCPUs , distributed
  memory, distributed I/O and time Synchronization.

Contributors

  this part is not to establish who owns what portions of the
  code base, but to provide a set of names that developers can consult when they
  have a question about a particular subset and also to provide a set of names
  to be CC'd when submitting a patch to obtain appropriate review.

  Trusted Cloud Group · Shanghai Key Laboratory 
  of Scalable Computing and Systems, Shanghai Jiao Tong University

  - Prof. Zhengwei Qi <qizhwei@sjtu.edu.cn>
  - Prof. Haibing Guan <hbguan@cs.sjtu.edu.cn>

  - Zhuocheng Ding <tcbbd@sjtu.edu.cn>
  - Yubin Chen <binsschen@sjtu.edu.cn>
  - Jin Zhang <jzhang3002@sjtu.edu.cn>
  - Yun Wang <yunwang94@sjtu.edu.cn>
  - Jiacheng Ma <jcma@umich.edu>
  - Boshi Yu <201608ybs@sjtu.edu.cn
  - Xingguo Jia <jiaxg1998@sjtu.edu.cn>
  - Weiye Chen <jcma@umich.edu>
  - Chenggang Wu <wuchenggang@sjtu.edu.cn>
  - Yuxin Xiang <xiangyuxin@sjtu.edu.cn>

  Electronics and Telecommunications Research Institute (South Korea)

  - Baik Song An<bsahn@etri.re.kr>

About Linux

          Linux kernel release 4.x <http://kernel.org/>

  These are the release notes for Linux version 4.  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 clone of the operating system Unix, written from scratch by
    Linus Torvalds with assistance from a loosely-knit team of hackers across
    the Net. It aims towards POSIX and Single UNIX Specification 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 multistack networking including IPv4 and IPv6.

    It is distributed under the GNU General Public License - see the
    accompanying COPYING file for more details.

  ON WHAT HARDWARE DOES IT RUN?

    Although originally developed first for 32-bit x86-based PCs (386 or higher),
    today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and
    UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell,
    IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS,
    Xtensa, Tilera TILE, AVR32, ARC and Renesas M32R architectures.

    Linux is easily portable to most general-purpose 32- or 64-bit architectures
    as long as they have a paged memory management unit (PMMU) and a port of the
    GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has
    also been ported to a number of architectures without a PMMU, although
    functionality is then obviously somewhat limited.
    Linux has also been ported to itself. You can now run the kernel as a
    userspace application - this is called UserMode Linux (UML).

  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 files in the 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.  Please read the Changes file, as it
    contains information about the problems, which may result by upgrading
    your kernel.

  - The Documentation/DocBook/ subdirectory contains several guides for
    kernel developers and users.  These guides can be rendered in a
    number of formats:  PostScript (.ps), PDF, HTML, & man-pages, among others.
    After installation, "make psdocs", "make pdfdocs", "make htmldocs",
    or "make mandocs" will render the documentation in the requested format.

  INSTALLING the kernel source:

  - If you install the full sources, put the kernel tarball in a
    directory where you have permissions (e.g. your home directory) and
    unpack it:

      xz -cd linux-4.X.tar.xz | tar xvf -

    Replace "X" with the version number of the latest kernel.

    Do NOT use the /usr/src/linux area! This area has a (usually
    incomplete) set of kernel headers that are used by the library header
    files.  They should match the library, and not get messed up by
    whatever the kernel-du-jour happens to be.

  - You can also upgrade between 4.x releases by patching.  Patches are
    distributed in the xz format.  To install by patching, get all the
    newer patch files, enter the top level directory of the kernel source
    (linux-4.X) and execute:

      xz -cd ../patch-4.x.xz | patch -p1

    Replace "x" for all versions bigger than the version "X" of your current
    source tree, _in_order_, and you should be ok.  You may want to remove
    the backup files (some-file-name~ or some-file-name.orig), and make sure
    that there are no failed patches (some-file-name# or some-file-name.rej).
    If there are, either you or I have made a mistake.

    Unlike patches for the 4.x kernels, patches for the 4.x.y kernels
    (also known as the -stable kernels) are not incremental but instead apply
    directly to the base 4.x kernel.  For example, if your base kernel is 4.0
    and you want to apply the 4.0.3 patch, you must not first apply the 4.0.1
    and 4.0.2 patches. Similarly, if you are running kernel version 4.0.2 and
    want to jump to 4.0.3, you must first reverse the 4.0.2 patch (that is,
    patch -R) _before_ applying the 4.0.3 patch. You can read more on this in
    Documentation/applying-patches.txt

    Alternatively, the script patch-kernel can be used to automate this
    process.  It determines the current kernel version and applies any
    patches found.

      linux/scripts/patch-kernel linux

    The first argument in the command above is the location of the
    kernel source.  Patches are applied from the current directory, but
    an alternative directory can be specified as the second argument.

  - Make sure you have no stale .o files and dependencies lying around:

      cd linux
      make mrproper

    You should now have the sources correctly installed.

  SOFTWARE REQUIREMENTS

    Compiling and running the 4.x kernels requires up-to-date
    versions of various software packages.  Consult
    Documentation/Changes for the minimum version numbers required
    and how to get updates for these packages.  Beware that using
    excessively old versions of these packages can cause indirect
    errors that are very difficult to track down, so don't assume that
    you can just update packages when obvious problems arise during
    build or operation.

  BUILD directory for the kernel:

    When compiling the kernel, all output files will per default be
    stored together with the kernel source code.
    Using the option "make O=output/dir" allows you to specify an alternate
    place for the output files (including .config).
    Example:

      kernel source code: /usr/src/linux-4.X
      build directory:    /home/name/build/kernel

    To configure and build the kernel, use:

      cd /usr/src/linux-4.X
      make O=/home/name/build/kernel menuconfig
      make O=/home/name/build/kernel
      sudo make O=/home/name/build/kernel modules_install install

    Please note: If the 'O=output/dir' option is used, then it must be
    used for all invocations of make.

  CONFIGURING the kernel:

    Do not skip this step even if you are only upgrading one minor
    version.  New configuration options are added in each release, and
    odd problems will turn up if the configuration files are not set up
    as expected.  If you want to carry your existing configuration to a
    new version with minimal work, use "make oldconfig", which will
    only ask you for the answers to new questions.

  - Alternative configuration commands are:

      "make config"      Plain text interface.

      "make menuconfig"  Text based color menus, radiolists & dialogs.

      "make nconfig"     Enhanced text based color menus.

      "make xconfig"     Qt based configuration tool.

      "make gconfig"     GTK+ based configuration tool.

      "make oldconfig"   Default all questions based on the contents of
                          your existing ./.config file and asking about
                          new config symbols.

      "make silentoldconfig"
                          Like above, but avoids cluttering the screen
                          with questions already answered.
                          Additionally updates the dependencies.

      "make olddefconfig"
                          Like above, but sets new symbols to their default
                          values without prompting.

      "make defconfig"   Create a ./.config file by using the default
                          symbol values from either arch/$ARCH/defconfig
                          or arch/$ARCH/configs/${PLATFORM}_defconfig,
                          depending on the architecture.

      "make ${PLATFORM}_defconfig"
                          Create a ./.config file by using the default
                          symbol values from
                          arch/$ARCH/configs/${PLATFORM}_defconfig.
                          Use "make help" to get a list of all available
                          platforms of your architecture.

      "make allyesconfig"
                          Create a ./.config file by setting symbol
                          values to 'y' as much as possible.

      "make allmodconfig"
                          Create a ./.config file by setting symbol
                          values to 'm' as much as possible.

      "make allnoconfig" Create a ./.config file by setting symbol
                          values to 'n' as much as possible.

      "make randconfig"  Create a ./.config file by setting symbol
                          values to random values.

      "make localmodconfig" Create a config based on current config and
                            loaded modules (lsmod). Disables any module
                            option that is not needed for the loaded modules.

                            To create a localmodconfig for another machine,
                            store the lsmod of that machine into a file
                            and pass it in as a LSMOD parameter.

                    target$ lsmod > /tmp/mylsmod
                    target$ scp /tmp/mylsmod host:/tmp

                    host$ make LSMOD=/tmp/mylsmod localmodconfig

                            The above also works when cross compiling.

      "make localyesconfig" Similar to localmodconfig, except it will convert
                            all module options to built in (=y) options.

    You can find more information on using the Linux kernel config tools
    in Documentation/kbuild/kconfig.txt.

  - 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

      - 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 "development",
        "experimental", or "debugging" features.

  COMPILING the kernel:

  - Make sure you have at least gcc 3.2 available.
    For more information, refer to Documentation/Changes.

    Please note that you can still run a.out user programs with this kernel.

  - Do a "make" to create a compressed kernel image. It is also
    possible to do "make install" if you have lilo installed to suit the
    kernel makefiles, but you may want to check your particular lilo setup first.

    To do the actual install, you have to be root, but none of the normal
    build should require that. Don't take the name of root in vain.

  - If you configured any of the parts of the kernel as `modules', you
    will also have to do "make modules_install".

  - Verbose kernel compile/build output:

    Normally, the kernel build system runs in a fairly quiet mode (but not
    totally silent).  However, sometimes you or other kernel developers need
    to see compile, link, or other commands exactly as they are executed.
    For this, use "verbose" build mode.  This is done by passing
    "V=1" to the "make" command, e.g.

      make V=1 all

    To have the build system also tell the reason for the rebuild of each
    target, use "V=2".  The default is "V=0".

  - 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.  Make sure you keep a
    backup of the modules corresponding to that kernel, as well.  If you
    are installing a new kernel with the same version number as your
    working kernel, make a backup of your modules directory before you
    do a "make modules_install".

    Alternatively, before compiling, use the kernel config option
    "LOCALVERSION" to append a unique suffix to the regular kernel version.
    LOCALVERSION can be set in the "General Setup" menu.

  - In order to boot your new kernel, you'll need to copy the kernel
    image (e.g. .../linux/arch/x86/boot/bzImage after compilation)
    to the place where your regular bootable kernel is found.

  - Booting a kernel directly from a floppy without the assistance of a
    bootloader such as LILO, is no longer supported.

    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, /boot/vmlinuz, /bzImage or
    /boot/bzImage.  To use the new kernel, save a copy of the old image
    and copy the new image over the old one.  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 (torvalds@linux-foundation.org), and possibly to any other
    relevant mailing-list or to the newsgroup.

  - 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

  - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump
    as is, otherwise you will have to use the "ksymoops" program to make
    sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred).
    This utility can be downloaded from
    ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ .
    Alternatively, you can 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.  Please read the REPORTING-BUGS document for details.

  - Alternatively, 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/x86/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.