android_kernel_xiaomi_sm8350/include/linux/firmware-map.h
Bernhard Walle 69ac9cd629 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 <bwalle@suse.de>
Acked-by: Greg KH <gregkh@suse.de>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: kexec@lists.infradead.org
Cc: yhlu.kernel@gmail.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-08 17:55:41 +02:00

75 lines
2.1 KiB
C

/*
* include/linux/firmware-map.h:
* Copyright (C) 2008 SUSE LINUX Products GmbH
* by Bernhard Walle <bwalle@suse.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License v2.0 as published by
* the Free Software Foundation
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#ifndef _LINUX_FIRMWARE_MAP_H
#define _LINUX_FIRMWARE_MAP_H
#include <linux/list.h>
#include <linux/kobject.h>
/*
* provide a dummy interface if CONFIG_FIRMWARE_MEMMAP is disabled
*/
#ifdef CONFIG_FIRMWARE_MEMMAP
/**
* Adds a firmware mapping entry. This function uses kmalloc() for memory
* allocation. Use firmware_map_add_early() if you want to use the bootmem
* allocator.
*
* That function must be called before late_initcall.
*
* @start: Start of the memory range.
* @end: End of the memory range (inclusive).
* @type: Type of the memory range.
*
* Returns 0 on success, or -ENOMEM if no memory could be allocated.
*/
int firmware_map_add(resource_size_t start, resource_size_t end,
const char *type);
/**
* Adds a firmware mapping entry. This function uses the bootmem allocator
* for memory allocation. Use firmware_map_add() if you want to use kmalloc().
*
* That function must be called before late_initcall.
*
* @start: Start of the memory range.
* @end: End of the memory range (inclusive).
* @type: Type of the memory range.
*
* Returns 0 on success, or -ENOMEM if no memory could be allocated.
*/
int firmware_map_add_early(resource_size_t start, resource_size_t end,
const char *type);
#else /* CONFIG_FIRMWARE_MEMMAP */
static inline int firmware_map_add(resource_size_t start, resource_size_t end,
const char *type)
{
return 0;
}
static inline int firmware_map_add_early(resource_size_t start,
resource_size_t end, const char *type)
{
return 0;
}
#endif /* CONFIG_FIRMWARE_MEMMAP */
#endif /* _LINUX_FIRMWARE_MAP_H */