From 69ac9cd629ca96e59f34eb4ccd12d00b2c8276a7 Mon Sep 17 00:00:00 2001 From: Bernhard Walle Date: Fri, 27 Jun 2008 13:12:54 +0200 Subject: sysfs: add /sys/firmware/memmap 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 Acked-by: Greg KH Acked-by: Vivek Goyal Cc: kexec@lists.infradead.org Cc: yhlu.kernel@gmail.com Signed-off-by: Ingo Molnar --- drivers/firmware/Kconfig | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'drivers/firmware/Kconfig') diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig index dc2cec6..ebb9e51 100644 --- a/drivers/firmware/Kconfig +++ b/drivers/firmware/Kconfig @@ -26,6 +26,16 @@ config EDD_OFF kernel. Say N if you want EDD enabled by default. EDD can be dynamically set using the kernel parameter 'edd={on|skipmbr|off}'. +config FIRMWARE_MEMMAP + bool "Add firmware-provided memory map to sysfs" if EMBEDDED + default (X86_64 || X86_32) + help + Add the firmware-provided (unmodified) memory map to /sys/firmware/memmap. + That memory map is used for example by kexec to set up parameter area + for the next kernel, but can also be used for debugging purposes. + + See also Documentation/ABI/testing/sysfs-firmware-memmap. + config EFI_VARS tristate "EFI Variable Support via sysfs" depends on EFI -- cgit v1.1