linux_kernel/arch/x86/include/uapi/asm/e820.h

#ifndef _UAPI_ASM_X86_E820_H
#define _UAPI_ASM_X86_E820_H
#define E820MAP	0x2d0		/* our map */
#define E820MAX	128		/* number of entries in E820MAP */

/*
 * Legacy E820 BIOS limits us to 128 (E820MAX) nodes due to the
 * constrained space in the zeropage.  If we have more nodes than
 * that, and if we've booted off EFI firmware, then the EFI tables
 * passed us from the EFI firmware can list more nodes.  Size our
 * internal memory map tables to have room for these additional
 * nodes, based on up to three entries per node for which the
 * kernel was built: MAX_NUMNODES == (1 << CONFIG_NODES_SHIFT),
 * plus E820MAX, allowing space for the possible duplicate E820
 * entries that might need room in the same arrays, prior to the
 * call to sanitize_e820_map() to remove duplicates.  The allowance
 * of three memory map entries per node is "enough" entries for
 * the initial hardware platform motivating this mechanism to make
 * use of additional EFI map entries.  Future platforms may want
 * to allow more than three entries per node or otherwise refine
 * this size.
 */

#ifndef __KERNEL__
#define E820_X_MAX E820MAX
#endif

#define E820NR	0x1e8		/* # entries in E820MAP */

#define E820_RAM	1
#define E820_RESERVED	2
#define E820_ACPI	3
#define E820_NVS	4
#define E820_UNUSABLE	5


/*
 * reserved RAM used by kernel itself
 * if CONFIG_INTEL_TXT is enabled, memory of this type will be
 * included in the S3 integrity calculation and so should not include
 * any memory that BIOS might alter over the S3 transition
 */
#define E820_RESERVED_KERN        128

#ifndef __ASSEMBLY__
#include <linux/types.h>
struct e820entry {
	__u64 addr;	/* start of memory segment */
	__u64 size;	/* size of memory segment */
	__u32 type;	/* type of memory segment */
} __attribute__((packed));

struct e820map {
	__u32 nr_map;
	struct e820entry map[E820_X_MAX];
};

#define ISA_START_ADDRESS	0xa0000
#define ISA_END_ADDRESS		0x100000

#define BIOS_BEGIN		0x000a0000
#define BIOS_END		0x00100000

#define BIOS_ROM_BASE		0xffe00000
#define BIOS_ROM_END		0xffffffff

#endif /* __ASSEMBLY__ */


#endif /* _UAPI_ASM_X86_E820_H */