User Tools

Site Tools


man_pages:linux:ubuntu:jammy:memdump_8

jammy (8) memdump.8.gz

Provided by: memdump_1.01-9_amd64 bug

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
  1. 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.
  1. 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.
  1. 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.
  1. 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).
  1. 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.
  1. 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)
man_pages/linux/ubuntu/jammy/memdump_8.txt · Last modified: 2023/08/15 16:40 by 127.0.0.1