====== ROM Dumping ======

Sometimes it can be useful to dump PCI expansion ROMs for debugging and troubleshooting purposes.  This page shows how to extract PCI expansion ROM contents.

===== ROM Dumping on Linux =====

Sysfs provides access to all PCI devices on a system ([[http://lxr.linux.no/linux/Documentation/filesystems/sysfs-pci.txt|sysfs-pci.txt documentation]]).  It is possible to map in expansion ROMs in order to dump their contents.

First select the PCI device you want to dump the ROM from:

  # lspci -nn      # this lists PCI devices and their bus IDs
  00:00.0 Host bridge [0600]: Intel Corporation Mobile 915GM/PM/GMS/910GML Express Processor to DRAM Controller [8086:2590] (rev 04)
  00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller [8086:2592] (rev 04)
  [...]

Enable the expansion ROM for the device:

  # cd /sys/bus/pci/devices/0000\:00\:02.0  # the VGA controller from above
  # echo 1 >rom

Dump the ROM contents:

  # cp rom /tmp/rom_dump

An Alternate way to dump the ROM contents (the first way may truncate the ROM):

  # dd if=rom of=/tmp/rom_dump

Disable the expansion ROM for the device:

  # echo 0 >rom