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>
hifive-unleashed-5.1
Bernhard Walle
Ingo Molnar
parent
6247943d8a
commit
69ac9cd629
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@ -0,0 +1,71 @@
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What: /sys/firmware/memmap/
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Date: June 2008
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Contact: Bernhard Walle <bwalle@suse.de>
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Description:
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On all platforms, the firmware provides a memory map which the
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kernel reads. The resources from that memory map are registered
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in the kernel resource tree and exposed to userspace via
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/proc/iomem (together with other resources).
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However, on most architectures that firmware-provided memory
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map is modified afterwards by the kernel itself, either because
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the kernel merges that memory map with other information or
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just because the user overwrites that memory map via command
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line.
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kexec needs the raw firmware-provided memory map to setup the
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parameter segment of the kernel that should be booted with
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kexec. Also, the raw memory map is useful for debugging. For
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that reason, /sys/firmware/memmap is an interface that provides
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the raw memory map to userspace.
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The structure is as follows: Under /sys/firmware/memmap there
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are subdirectories with the number of the entry as their name:
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/sys/firmware/memmap/0
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/sys/firmware/memmap/1
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/sys/firmware/memmap/2
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/sys/firmware/memmap/3
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...
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The maximum depends on the number of memory map entries provided
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by the firmware. The order is just the order that the firmware
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provides.
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Each directory contains three files:
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start : The start address (as hexadecimal number with the
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'0x' prefix).
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end : The end address, inclusive (regardless whether the
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firmware provides inclusive or exclusive ranges).
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type : Type of the entry as string. See below for a list of
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valid types.
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So, for example:
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/sys/firmware/memmap/0/start
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/sys/firmware/memmap/0/end
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/sys/firmware/memmap/0/type
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/sys/firmware/memmap/1/start
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...
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Currently following types exist:
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- System RAM
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- ACPI Tables
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- ACPI Non-volatile Storage
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- reserved
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Following shell snippet can be used to display that memory
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map in a human-readable format:
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-------------------- 8< ----------------------------------------
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#!/bin/bash
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cd /sys/firmware/memmap
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for dir in * ; do
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start=$(cat $dir/start)
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end=$(cat $dir/end)
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type=$(cat $dir/type)
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printf "%016x-%016x (%s)\n" $start $[ $end +1] "$type"
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done
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-------------------- >8 ----------------------------------------
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@ -26,6 +26,16 @@ config EDD_OFF
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kernel. Say N if you want EDD enabled by default. EDD can be dynamically set
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using the kernel parameter 'edd={on|skipmbr|off}'.
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config FIRMWARE_MEMMAP
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bool "Add firmware-provided memory map to sysfs" if EMBEDDED
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default (X86_64 || X86_32)
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help
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Add the firmware-provided (unmodified) memory map to /sys/firmware/memmap.
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That memory map is used for example by kexec to set up parameter area
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for the next kernel, but can also be used for debugging purposes.
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See also Documentation/ABI/testing/sysfs-firmware-memmap.
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config EFI_VARS
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tristate "EFI Variable Support via sysfs"
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depends on EFI
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@ -10,3 +10,4 @@ obj-$(CONFIG_DCDBAS) += dcdbas.o
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obj-$(CONFIG_DMIID) += dmi-id.o
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obj-$(CONFIG_ISCSI_IBFT_FIND) += iscsi_ibft_find.o
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obj-$(CONFIG_ISCSI_IBFT) += iscsi_ibft.o
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obj-$(CONFIG_FIRMWARE_MEMMAP) += memmap.o
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@ -0,0 +1,205 @@
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/*
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* linux/drivers/firmware/memmap.c
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* Copyright (C) 2008 SUSE LINUX Products GmbH
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* by Bernhard Walle <bwalle@suse.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License v2.0 as published by
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* the Free Software Foundation
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <linux/string.h>
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#include <linux/firmware-map.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/bootmem.h>
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/*
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* Data types ------------------------------------------------------------------
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*/
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/*
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* Firmware map entry. Because firmware memory maps are flat and not
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* hierarchical, it's ok to organise them in a linked list. No parent
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* information is necessary as for the resource tree.
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*/
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struct firmware_map_entry {
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resource_size_t start; /* start of the memory range */
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resource_size_t end; /* end of the memory range (incl.) */
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const char *type; /* type of the memory range */
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struct list_head list; /* entry for the linked list */
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struct kobject kobj; /* kobject for each entry */
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};
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/*
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* Forward declarations --------------------------------------------------------
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*/
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static ssize_t memmap_attr_show(struct kobject *kobj,
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struct attribute *attr, char *buf);
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static ssize_t start_show(struct firmware_map_entry *entry, char *buf);
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static ssize_t end_show(struct firmware_map_entry *entry, char *buf);
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static ssize_t type_show(struct firmware_map_entry *entry, char *buf);
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/*
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* Static data -----------------------------------------------------------------
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*/
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struct memmap_attribute {
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struct attribute attr;
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ssize_t (*show)(struct firmware_map_entry *entry, char *buf);
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};
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struct memmap_attribute memmap_start_attr = __ATTR_RO(start);
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struct memmap_attribute memmap_end_attr = __ATTR_RO(end);
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struct memmap_attribute memmap_type_attr = __ATTR_RO(type);
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/*
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* These are default attributes that are added for every memmap entry.
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*/
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static struct attribute *def_attrs[] = {
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&memmap_start_attr.attr,
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&memmap_end_attr.attr,
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&memmap_type_attr.attr,
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NULL
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};
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static struct sysfs_ops memmap_attr_ops = {
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.show = memmap_attr_show,
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};
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static struct kobj_type memmap_ktype = {
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.sysfs_ops = &memmap_attr_ops,
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.default_attrs = def_attrs,
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};
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/*
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* Registration functions ------------------------------------------------------
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*/
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/*
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* Firmware memory map entries
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*/
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static LIST_HEAD(map_entries);
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/**
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* Common implementation of firmware_map_add() and firmware_map_add_early()
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* which expects a pre-allocated struct firmware_map_entry.
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*
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* @start: Start of the memory range.
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* @end: End of the memory range (inclusive).
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* @type: Type of the memory range.
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* @entry: Pre-allocated (either kmalloc() or bootmem allocator), uninitialised
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* entry.
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*/
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static int firmware_map_add_entry(resource_size_t start, resource_size_t end,
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const char *type,
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struct firmware_map_entry *entry)
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{
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BUG_ON(start > end);
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entry->start = start;
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entry->end = end;
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entry->type = type;
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INIT_LIST_HEAD(&entry->list);
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kobject_init(&entry->kobj, &memmap_ktype);
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list_add_tail(&entry->list, &map_entries);
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return 0;
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}
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/*
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* See <linux/firmware-map.h> for documentation.
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*/
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int firmware_map_add(resource_size_t start, resource_size_t end,
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const char *type)
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{
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struct firmware_map_entry *entry;
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entry = kmalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC);
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WARN_ON(!entry);
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if (!entry)
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return -ENOMEM;
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return firmware_map_add_entry(start, end, type, entry);
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}
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/*
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* See <linux/firmware-map.h> for documentation.
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*/
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int __init firmware_map_add_early(resource_size_t start, resource_size_t end,
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const char *type)
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{
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struct firmware_map_entry *entry;
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entry = alloc_bootmem_low(sizeof(struct firmware_map_entry));
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WARN_ON(!entry);
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if (!entry)
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return -ENOMEM;
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return firmware_map_add_entry(start, end, type, entry);
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}
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/*
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* Sysfs functions -------------------------------------------------------------
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*/
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static ssize_t start_show(struct firmware_map_entry *entry, char *buf)
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{
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return snprintf(buf, PAGE_SIZE, "0x%llx\n", entry->start);
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}
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static ssize_t end_show(struct firmware_map_entry *entry, char *buf)
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{
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return snprintf(buf, PAGE_SIZE, "0x%llx\n", entry->end);
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}
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static ssize_t type_show(struct firmware_map_entry *entry, char *buf)
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{
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return snprintf(buf, PAGE_SIZE, "%s\n", entry->type);
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}
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#define to_memmap_attr(_attr) container_of(_attr, struct memmap_attribute, attr)
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#define to_memmap_entry(obj) container_of(obj, struct firmware_map_entry, kobj)
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static ssize_t memmap_attr_show(struct kobject *kobj,
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struct attribute *attr, char *buf)
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{
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struct firmware_map_entry *entry = to_memmap_entry(kobj);
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struct memmap_attribute *memmap_attr = to_memmap_attr(attr);
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return memmap_attr->show(entry, buf);
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}
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/*
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* Initialises stuff and adds the entries in the map_entries list to
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* sysfs. Important is that firmware_map_add() and firmware_map_add_early()
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* must be called before late_initcall.
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*/
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static int __init memmap_init(void)
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{
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int i = 0;
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struct firmware_map_entry *entry;
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struct kset *memmap_kset;
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memmap_kset = kset_create_and_add("memmap", NULL, firmware_kobj);
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WARN_ON(!memmap_kset);
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if (!memmap_kset)
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return -ENOMEM;
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list_for_each_entry(entry, &map_entries, list) {
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entry->kobj.kset = memmap_kset;
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kobject_add(&entry->kobj, NULL, "%d", i++);
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}
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return 0;
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}
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late_initcall(memmap_init);
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@ -0,0 +1,74 @@
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/*
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* include/linux/firmware-map.h:
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* Copyright (C) 2008 SUSE LINUX Products GmbH
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* by Bernhard Walle <bwalle@suse.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License v2.0 as published by
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* the Free Software Foundation
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#ifndef _LINUX_FIRMWARE_MAP_H
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#define _LINUX_FIRMWARE_MAP_H
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#include <linux/list.h>
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#include <linux/kobject.h>
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/*
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* provide a dummy interface if CONFIG_FIRMWARE_MEMMAP is disabled
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*/
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#ifdef CONFIG_FIRMWARE_MEMMAP
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/**
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* Adds a firmware mapping entry. This function uses kmalloc() for memory
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* allocation. Use firmware_map_add_early() if you want to use the bootmem
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* allocator.
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*
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* That function must be called before late_initcall.
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*
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* @start: Start of the memory range.
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* @end: End of the memory range (inclusive).
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* @type: Type of the memory range.
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*
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* Returns 0 on success, or -ENOMEM if no memory could be allocated.
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*/
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int firmware_map_add(resource_size_t start, resource_size_t end,
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const char *type);
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/**
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* Adds a firmware mapping entry. This function uses the bootmem allocator
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* for memory allocation. Use firmware_map_add() if you want to use kmalloc().
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*
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* That function must be called before late_initcall.
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*
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* @start: Start of the memory range.
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* @end: End of the memory range (inclusive).
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* @type: Type of the memory range.
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*
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* Returns 0 on success, or -ENOMEM if no memory could be allocated.
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*/
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int firmware_map_add_early(resource_size_t start, resource_size_t end,
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const char *type);
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#else /* CONFIG_FIRMWARE_MEMMAP */
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static inline int firmware_map_add(resource_size_t start, resource_size_t end,
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const char *type)
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{
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return 0;
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}
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static inline int firmware_map_add_early(resource_size_t start,
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resource_size_t end, const char *type)
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{
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return 0;
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}
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#endif /* CONFIG_FIRMWARE_MEMMAP */
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#endif /* _LINUX_FIRMWARE_MAP_H */
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Loading…
Reference in New Issue