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.

       -s 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

                                                                                       MEMDUMP(8)