#include <asm/cpufeature.h>
/*
- * The e820 table is the array 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 firmware and bootloader passes us an E820 table that is the primary
+ * physical memory layout description available about x86 systems.
*
- * The e820_table_saved is directly saved after the BIOS-provided memory map is
- * copied. It doesn't get modified afterwards. It's registered for the
- * /sys/firmware/memmap interface.
+ * The kernel takes the e820 memory layout and optionally modifies it with
+ * quirks and other tweaks, and feeds that into the generic Linux memory
+ * allocation code routines via a platform independent interface (memblock, etc.).
*
- * 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.
+ * We organize the E820 table into two main data structures:
+ *
+ * - 'e820_table_firmware': the original firmware version passed to us by the
+ * bootloader - not modified by the kernel. We use this to:
+ *
+ * - inform the user about the firmware's notion of memory layout
+ * via /sys/firmware/memmap
+ *
+ * - the hibernation code uses it to generate a kernel-independent MD5
+ * fingerprint of the physical memory layout of a system.
+ *
+ * - kexec, which is a bootloader in disguise, uses the original e820
+ * layout to pass to the kexec-ed kernel. This way the original kernel
+ * can have a restricted e820 map while the kexec()-ed kexec-kernel
+ * can have access to full memory - etc.
+ *
+ * - 'e820_table': this is the main e820 table that is massaged by the
+ * low level x86 platform code, or modified by boot parameters, before
+ * passed on to higher level MM layers.
+ *
+ * Once the e820 map has been converted to the standard Linux memory layout
+ * information its role stops - modifying it has no effect and does not get
+ * re-propagated. So itsmain role is a temporary bootstrap storage of firmware
+ * specific memory layout data during early bootup.
*/
-static struct e820_table e820_table_init __initdata;
-static struct e820_table initial_e820_table_saved __initdata;
-struct e820_table *e820_table __refdata = &e820_table_init;
-struct e820_table *e820_table_saved __refdata = &initial_e820_table_saved;
+static struct e820_table e820_table_init __initdata;
+static struct e820_table e820_table_firmware_init __initdata;
+
+struct e820_table *e820_table __refdata = &e820_table_init;
+struct e820_table *e820_table_firmware __refdata = &e820_table_firmware_init;
/* For PCI or other memory-mapped resources */
unsigned long pci_mem_start = 0xaeedbabe;
return __e820_update_range(e820_table, start, size, old_type, new_type);
}
-static u64 __init e820_update_range_saved(u64 start, u64 size,
+static u64 __init e820_update_range_firmware(u64 start, u64 size,
unsigned old_type, unsigned new_type)
{
- return __e820_update_range(e820_table_saved, start, size, old_type,
+ return __e820_update_range(e820_table_firmware, start, size, old_type,
new_type);
}
printk(KERN_INFO "e820: modified physical RAM map:\n");
e820_print_map("modified");
}
-static void __init update_e820_table_saved(void)
+static void __init update_e820_table_firmware(void)
{
- sanitize_e820_table(e820_table_saved->entries, ARRAY_SIZE(e820_table_saved->entries), &e820_table_saved->nr_entries);
+ sanitize_e820_table(e820_table_firmware->entries, ARRAY_SIZE(e820_table_firmware->entries), &e820_table_firmware->nr_entries);
}
#define MAX_GAP_END 0x100000000ull
/*
/*
* Called late during init, in free_initmem().
*
- * Initial e820 and e820_table_saved are largish __initdata arrays.
+ * Initial e820 and e820_table_firmware are largish __initdata arrays.
* Copy them to (usually much smaller) dynamically allocated area.
* This is done after all tweaks we ever do to them:
* all functions which modify them are __init functions,
memcpy(n, e820_table, size);
e820_table = n;
- size = offsetof(struct e820_table, entries) + sizeof(struct e820_entry) * e820_table_saved->nr_entries;
+ size = offsetof(struct e820_table, entries) + sizeof(struct e820_entry) * e820_table_firmware->nr_entries;
n = kmalloc(size, GFP_KERNEL);
BUG_ON(!n);
- memcpy(n, e820_table_saved, size);
- e820_table_saved = n;
+ memcpy(n, e820_table_firmware, size);
+ e820_table_firmware = n;
}
/**
#endif
/*
- * pre allocated 4k and reserved it in memblock and e820_table_saved
+ * pre allocated 4k and reserved it in memblock and e820_table_firmware
*/
u64 __init early_reserve_e820(u64 size, u64 align)
{
addr = __memblock_alloc_base(size, align, MEMBLOCK_ALLOC_ACCESSIBLE);
if (addr) {
- e820_update_range_saved(addr, size, E820_RAM, E820_RESERVED);
- printk(KERN_INFO "e820: update e820_table_saved for early_reserve_e820\n");
- update_e820_table_saved();
+ e820_update_range_firmware(addr, size, E820_RAM, E820_RESERVED);
+ printk(KERN_INFO "e820: update e820_table_firmware for early_reserve_e820\n");
+ update_e820_table_firmware();
}
return addr;
res++;
}
- for (i = 0; i < e820_table_saved->nr_entries; i++) {
- struct e820_entry *entry = &e820_table_saved->entries[i];
+ for (i = 0; i < e820_table_firmware->nr_entries; i++) {
+ struct e820_entry *entry = &e820_table_firmware->entries[i];
firmware_map_add_early(entry->addr,
entry->addr + entry->size,
e820_type_to_string(entry->type));
char *who;
who = x86_init.resources.memory_setup();
- memcpy(e820_table_saved, e820_table, sizeof(struct e820_table));
+ memcpy(e820_table_firmware, e820_table, sizeof(struct e820_table));
printk(KERN_INFO "e820: BIOS-provided physical RAM map:\n");
e820_print_map(who);
}
projects / karo-tx-linux.git / commitdiff