[PATCH 1/2] Add /sys/firmware/memmap
gregkh at suse.de
Fri Jun 27 16:56:25 EDT 2008
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
> 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< --------------------------
> 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"
> --------- >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.
More information about the kexec