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Subject[PATCH 2/3] Use /proc/firmware_mem for x86 (e820)
Date
This patch copies the E820 map very early, before the kernel applies various
operations. That copy is used later to register only the BIOS-provided E820
map later in the resource tree for /proc/firmware_mem.


Signed-off-by: Bernhard Walle <bwalle@suse.de>
---
arch/x86/kernel/e820.c | 44 ++++++++++++++++++++++++++++++++++----------
include/asm-x86/e820.h | 2 ++
2 files changed, 36 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 7b613d2..f5b1736 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -27,7 +27,22 @@
#include <asm/setup.h>
#include <asm/trampoline.h>

+/*
+ * The e820 map is the map that gets modified e.g. with command line parameters
+ * and that is also registered with modifications in the kernel resource tree
+ * with the iomem_resource as parent.
+ *
+ * The e820_saved is directly saved after the BIOS-provided memory map is
+ * copied. It doesn't get modified afterwards. It's registered in the
+ * resource system of the kernel with firmware_mem_resource as parent.
+ *
+ * That memory map is not modified and is used as base for kexec. The kexec'd
+ * kernel should get the same memory map as the firmware provides. Then the
+ * user can e.g. boot the original kernel with mem=1G while still booting the
+ * next kernel with full memory.
+ */
struct e820map e820;
+struct e820map e820_saved;

/* For PCI or other memory-mapped resources */
unsigned long pci_mem_start = 0xaeedbabe;
@@ -999,24 +1014,22 @@ void __init finish_e820_parsing(void)
}
}

-/*
- * Mark e820 reserved areas as busy for the resource manager.
- */
-void __init e820_reserve_resources(void)
+static void __init e820_reserve_resources_map(struct e820map *map,
+ struct resource *root)
{
int i;
struct resource *res;

- res = alloc_bootmem_low(sizeof(struct resource) * e820.nr_map);
- for (i = 0; i < e820.nr_map; i++) {
- switch (e820.map[i].type) {
+ res = alloc_bootmem_low(sizeof(struct resource) * map->nr_map);
+ for (i = 0; i < map->nr_map; i++) {
+ switch (map->map[i].type) {
case E820_RAM: res->name = "System RAM"; break;
case E820_ACPI: res->name = "ACPI Tables"; break;
case E820_NVS: res->name = "ACPI Non-volatile Storage"; break;
default: res->name = "reserved";
}
- res->start = e820.map[i].addr;
- res->end = res->start + e820.map[i].size - 1;
+ res->start = map->map[i].addr;
+ res->end = res->start + map->map[i].size - 1;
#ifndef CONFIG_RESOURCES_64BIT
if (res->end > 0x100000000ULL) {
res++;
@@ -1024,11 +1037,20 @@ void __init e820_reserve_resources(void)
}
#endif
res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
- insert_resource(&iomem_resource, res);
+ insert_resource(root, res);
res++;
}
}

+/*
+ * Mark e820 reserved areas as busy for the resource manager.
+ */
+void __init e820_reserve_resources(void)
+{
+ e820_reserve_resources_map(&e820, &iomem_resource);
+ e820_reserve_resources_map(&e820_saved, &firmware_mem_resource);
+}
+
char *__init default_machine_specific_memory_setup(void)
{
char *who = "BIOS-e820";
@@ -1062,6 +1084,8 @@ char *__init default_machine_specific_memory_setup(void)
e820_add_region(HIGH_MEMORY, mem_size << 10, E820_RAM);
}

+ memcpy(&e820_saved, &e820, sizeof(struct e820map));
+
/* In case someone cares... */
return who;
}
diff --git a/include/asm-x86/e820.h b/include/asm-x86/e820.h
index 668a0d7..48e7181 100644
--- a/include/asm-x86/e820.h
+++ b/include/asm-x86/e820.h
@@ -56,7 +56,9 @@ struct e820map {
struct e820entry map[E820_X_MAX];
};

+/* see comment in arch/x86/kernel/e820.c */
extern struct e820map e820;
+extern struct e820map e820_saved;

extern int e820_any_mapped(u64 start, u64 end, unsigned type);
extern int e820_all_mapped(u64 start, u64 end, unsigned type);
--
1.5.4.5


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