On Fri, Jun 27, 2008 at 01:12:54PM +0200, Bernhard Walle wrote: > This patch adds /sys/firmware/memmap interface that represents the BIOS > (or Firmware) provided memory map. The tree looks like: > > /sys/firmware/memmap/0/start (hex number) > end (hex number) > type (string) > ... /1/start > end > type > > With the following shell snippet one can print the memory map in the same form > the kernel prints itself when booting on x86 (the E820 map). > > --------- 8< -------------------------- > #!/bin/sh > cd /sys/firmware/memmap > for dir in * ; do > start=$(cat $dir/start) > end=$(cat $dir/end) > type=$(cat $dir/type) > printf "%016x-%016x (%s)\n" $start $[ $end +1] "$type" > done > --------- >8 -------------------------- > > That patch only provides the needed interface: > > 1. The sysfs interface. > 2. The structure and enumeration definition. > 3. The function firmware_map_add() and firmware_map_add_early() > that should be called from architecture code (E820/EFI, for > example) to add the contents to the interface. > > If the kernel is compiled without CONFIG_FIRMWARE_MEMMAP, the interface does > nothing without cluttering the architecture-specific code with #ifdef's. > > The purpose of the new interface is kexec: While /proc/iomem represents > the *used* memory map (e.g. modified via kernel parameters like 'memmap' > and 'mem'), the /sys/firmware/memmap tree represents the unmodified memory > map provided via the firmware. So kexec can: > > - use the original memory map for rebooting, > - use the /proc/iomem for setting up the ELF core headers for kdump > case that should only represent the memory of the system. > > The patch has been tested on i386 and x86_64. > > > Signed-off-by: Bernhard Walle <bwalle at suse.de> Acked-by: Greg Kroah-Hartman <gregkh at suse.de> x86 developers, feel free to add this to your tree, it looks fine to me. thanks, greg k-h
