mirror of
https://github.com/FEX-Emu/linux.git
synced 2024-12-21 00:42:16 +00:00
69ac9cd629
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>
72 lines
2.3 KiB
Plaintext
72 lines
2.3 KiB
Plaintext
What: /sys/firmware/memmap/
|
|
Date: June 2008
|
|
Contact: Bernhard Walle <bwalle@suse.de>
|
|
Description:
|
|
On all platforms, the firmware provides a memory map which the
|
|
kernel reads. The resources from that memory map are registered
|
|
in the kernel resource tree and exposed to userspace via
|
|
/proc/iomem (together with other resources).
|
|
|
|
However, on most architectures that firmware-provided memory
|
|
map is modified afterwards by the kernel itself, either because
|
|
the kernel merges that memory map with other information or
|
|
just because the user overwrites that memory map via command
|
|
line.
|
|
|
|
kexec needs the raw firmware-provided memory map to setup the
|
|
parameter segment of the kernel that should be booted with
|
|
kexec. Also, the raw memory map is useful for debugging. For
|
|
that reason, /sys/firmware/memmap is an interface that provides
|
|
the raw memory map to userspace.
|
|
|
|
The structure is as follows: Under /sys/firmware/memmap there
|
|
are subdirectories with the number of the entry as their name:
|
|
|
|
/sys/firmware/memmap/0
|
|
/sys/firmware/memmap/1
|
|
/sys/firmware/memmap/2
|
|
/sys/firmware/memmap/3
|
|
...
|
|
|
|
The maximum depends on the number of memory map entries provided
|
|
by the firmware. The order is just the order that the firmware
|
|
provides.
|
|
|
|
Each directory contains three files:
|
|
|
|
start : The start address (as hexadecimal number with the
|
|
'0x' prefix).
|
|
end : The end address, inclusive (regardless whether the
|
|
firmware provides inclusive or exclusive ranges).
|
|
type : Type of the entry as string. See below for a list of
|
|
valid types.
|
|
|
|
So, for example:
|
|
|
|
/sys/firmware/memmap/0/start
|
|
/sys/firmware/memmap/0/end
|
|
/sys/firmware/memmap/0/type
|
|
/sys/firmware/memmap/1/start
|
|
...
|
|
|
|
Currently following types exist:
|
|
|
|
- System RAM
|
|
- ACPI Tables
|
|
- ACPI Non-volatile Storage
|
|
- reserved
|
|
|
|
Following shell snippet can be used to display that memory
|
|
map in a human-readable format:
|
|
|
|
-------------------- 8< ----------------------------------------
|
|
#!/bin/bash
|
|
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 ----------------------------------------
|