linux/arch/x86/include/asm/e820.h
Bjorn Helgaas a2c606d53a x86: avoid high BIOS area when allocating address space
This prevents allocation of the last 2MB before 4GB.

The experiment described here shows Windows 7 ignoring the last 1MB:
https://bugzilla.kernel.org/show_bug.cgi?id=23542#c27

This patch ignores the top 2MB instead of just 1MB because H. Peter Anvin
says "There will be ROM at the top of the 32-bit address space; it's a fact
of the architecture, and on at least older systems it was common to have a
shadow 1 MiB below."

Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
2010-12-17 10:01:30 -08:00

150 lines
4.5 KiB
C

#ifndef _ASM_X86_E820_H
#define _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.
*/
/*
* Odd: 'make headers_check' complains about numa.h if I try
* to collapse the next two #ifdef lines to a single line:
* #if defined(__KERNEL__) && defined(CONFIG_EFI)
*/
#ifdef __KERNEL__
#ifdef CONFIG_EFI
#include <linux/numa.h>
#define E820_X_MAX (E820MAX + 3 * MAX_NUMNODES)
#else /* ! CONFIG_EFI */
#define E820_X_MAX E820MAX
#endif
#else /* ! __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
#ifdef __KERNEL__
/* see comment in arch/x86/kernel/e820.c */
extern struct e820map e820;
extern struct e820map e820_saved;
extern unsigned long pci_mem_start;
extern int e820_any_mapped(u64 start, u64 end, unsigned type);
extern int e820_all_mapped(u64 start, u64 end, unsigned type);
extern void e820_add_region(u64 start, u64 size, int type);
extern void e820_print_map(char *who);
extern int
sanitize_e820_map(struct e820entry *biosmap, int max_nr_map, u32 *pnr_map);
extern u64 e820_update_range(u64 start, u64 size, unsigned old_type,
unsigned new_type);
extern u64 e820_remove_range(u64 start, u64 size, unsigned old_type,
int checktype);
extern void update_e820(void);
extern void e820_setup_gap(void);
extern int e820_search_gap(unsigned long *gapstart, unsigned long *gapsize,
unsigned long start_addr, unsigned long long end_addr);
struct setup_data;
extern void parse_e820_ext(struct setup_data *data, unsigned long pa_data);
#if defined(CONFIG_X86_64) || \
(defined(CONFIG_X86_32) && defined(CONFIG_HIBERNATION))
extern void e820_mark_nosave_regions(unsigned long limit_pfn);
#else
static inline void e820_mark_nosave_regions(unsigned long limit_pfn)
{
}
#endif
#ifdef CONFIG_MEMTEST
extern void early_memtest(unsigned long start, unsigned long end);
#else
static inline void early_memtest(unsigned long start, unsigned long end)
{
}
#endif
extern unsigned long e820_end_of_ram_pfn(void);
extern unsigned long e820_end_of_low_ram_pfn(void);
extern u64 early_reserve_e820(u64 startt, u64 sizet, u64 align);
void memblock_x86_fill(void);
void memblock_find_dma_reserve(void);
extern void finish_e820_parsing(void);
extern void e820_reserve_resources(void);
extern void e820_reserve_resources_late(void);
extern void setup_memory_map(void);
extern char *default_machine_specific_memory_setup(void);
/*
* Returns true iff the specified range [s,e) is completely contained inside
* the ISA region.
*/
static inline bool is_ISA_range(u64 s, u64 e)
{
return s >= ISA_START_ADDRESS && e <= ISA_END_ADDRESS;
}
#endif /* __KERNEL__ */
#endif /* __ASSEMBLY__ */
#ifdef __KERNEL__
#include <linux/ioport.h>
#define HIGH_MEMORY (1024*1024)
#endif /* __KERNEL__ */
#endif /* _ASM_X86_E820_H */