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>
diff --git a/include/linux/firmware-map.h b/include/linux/firmware-map.h
new file mode 100644
index 0000000..acbdbcc
--- /dev/null
+++ b/include/linux/firmware-map.h
@@ -0,0 +1,74 @@
+/*
+ * 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 */