1#include <linux/kernel.h> 2#include <linux/init.h> 3 4#include <asm/setup.h> 5#include <asm/bios_ebda.h> 6 7#define BIOS_LOWMEM_KILOBYTES 0x413 8 9void __init reserve_ebda_region(void) 10{ 11 unsigned int lowmem, ebda_addr; 12 13 /* To determine the position of the EBDA and the */ 14 /* end of conventional memory, we need to look at */ 15 /* the BIOS data area. In a paravirtual environment */ 16 /* that area is absent. We'll just have to assume */ 17 /* that the paravirt case can handle memory setup */ 18 /* correctly, without our help. */ 19 if (paravirt_enabled()) 20 return; 21 22 /* end of low (conventional) memory */ 23 lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES); 24 lowmem <<= 10; 25 26 /* start of EBDA area */ 27 ebda_addr = get_bios_ebda(); 28 29 /* Fixup: bios puts an EBDA in the top 64K segment */ 30 /* of conventional memory, but does not adjust lowmem. */ 31 if ((lowmem - ebda_addr) <= 0x10000) 32 lowmem = ebda_addr; 33 34 /* Fixup: bios does not report an EBDA at all. */ 35 /* Some old Dells seem to need 4k anyhow (bugzilla 2990) */ 36 if ((ebda_addr == 0) && (lowmem >= 0x9f000)) 37 lowmem = 0x9f000; 38 39 /* Paranoia: should never happen, but... */ 40 if ((lowmem == 0) || (lowmem >= 0x100000)) 41 lowmem = 0x9f000; 42 43 /* reserve all memory between lowmem and the 1MB mark */ 44 reserve_early_overlap_ok(lowmem, 0x100000, "BIOS reserved"); 45} 46