NAME

       memdump - memory dumper

SYNOPSIS

       memdump [-kv] [-b buffer_size] [-d dump_size] [-m map_file] [-p page_size]

DESCRIPTION

       This  program  dumps system memory to the standard output stream, skipping over holes in memory maps.  By
       default, the program dumps the contents of physical memory (/dev/mem).

       Output is in the form of a  raw  dump;  if  necessary,  use  the  -m  option  to  capture  memory  layout
       information.

       Output  should  be  sent  off-host  over the network, to avoid changing all the memory in the file system
       cache. Use netcat, stunnel, or openssl, depending on your requirements.

       The size arguments below understand the k (kilo) m (mega)  and  g  (giga)  suffixes.  Suffixes  are  case
       insensitive.

       Options

       -k     Attempt to dump kernel memory (/dev/kmem) rather than physical memory.

              Warning:  this  can  lock  up  the  system to the point that you have to use the power switch (for
              example, Solaris 8 on 64-bit SPARC).

              Warning: this produces bogus results on Linux 2.2 kernels.

              Warning: this is very slow on 64-bit machines because the entire memory address range  has  to  be
              searched.

              Warning:  kernel  virtual  memory  mappings  change frequently. Depending on the operating system,
              mappings smaller than page_size or buffer_size may be missed or may be reported incorrectly.

       -b buffer_size (default: 0)
              Number of bytes per memory read operation. By default, the program uses the page_size value.

              Warning: a too large read buffer size causes memory to be missed on FreeBSD or Solaris.

       -d dump-size (default: 0)
              Number of memory bytes to dump. By default, the program runs until the memory  device  reports  an
              end-of-file  (Linux),  or  until it has dumped from /dev/mem as much memory as reported present by
              the kernel (FreeBSD, Solaris), or until pointer wrap-around happens.

              Warning: a too large value causes the program to spend a lot of time  skipping  over  non-existent
              memory on Solaris systems.

              Warning: a too large value causes the program to copy non-existent data on FreeBSD systems.

       -m map_file
              Write  the memory map to map_file, one entry per line.  Specify -m- to write to the standard error
              stream.  Each map entry consists of a region start address  and  the  first  address  beyond  that
              region. Addresses are separated by space, and are printed as hexadecimal numbers (0xhhhh).

       -p page_size (default: 0)
              Use page_size as the memory page size. By default the program uses the system page size.

              Warning: a too large page size causes memory to be missed while skipping over holes in memory.

       -v     Enable verbose logging for debugging purposes. Multiple -v options make the program more verbose.

BUGS

       On  many  hardware platforms the firmware (boot PROM, BIOS, etc.)  takes away some memory. This memory is
       not accessible through /dev/mem.

       This program should produce output in a format that supports structure information such as ELF.

LICENSE

       This software is distributed under the IBM Public License.

AUTHOR

       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       USA

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