mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-30 08:02:30 +00:00
0c51a965ed
This patch extracts the common part of head32.c and head64.c into head.c. Signed-off-by: Huang Ying <ying.huang@intel.com> Cc: andi@firstfloor.org Cc: mingo@redhat.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
55 lines
1.7 KiB
C
55 lines
1.7 KiB
C
#include <linux/kernel.h>
|
|
#include <linux/init.h>
|
|
|
|
#include <asm/setup.h>
|
|
#include <asm/bios_ebda.h>
|
|
|
|
#define BIOS_LOWMEM_KILOBYTES 0x413
|
|
|
|
/*
|
|
* The BIOS places the EBDA/XBDA at the top of conventional
|
|
* memory, and usually decreases the reported amount of
|
|
* conventional memory (int 0x12) too. This also contains a
|
|
* workaround for Dell systems that neglect to reserve EBDA.
|
|
* The same workaround also avoids a problem with the AMD768MPX
|
|
* chipset: reserve a page before VGA to prevent PCI prefetch
|
|
* into it (errata #56). Usually the page is reserved anyways,
|
|
* unless you have no PS/2 mouse plugged in.
|
|
*/
|
|
void __init reserve_ebda_region(void)
|
|
{
|
|
unsigned int lowmem, ebda_addr;
|
|
|
|
/* To determine the position of the EBDA and the */
|
|
/* end of conventional memory, we need to look at */
|
|
/* the BIOS data area. In a paravirtual environment */
|
|
/* that area is absent. We'll just have to assume */
|
|
/* that the paravirt case can handle memory setup */
|
|
/* correctly, without our help. */
|
|
if (paravirt_enabled())
|
|
return;
|
|
|
|
/* end of low (conventional) memory */
|
|
lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
|
|
lowmem <<= 10;
|
|
|
|
/* start of EBDA area */
|
|
ebda_addr = get_bios_ebda();
|
|
|
|
/* Fixup: bios puts an EBDA in the top 64K segment */
|
|
/* of conventional memory, but does not adjust lowmem. */
|
|
if ((lowmem - ebda_addr) <= 0x10000)
|
|
lowmem = ebda_addr;
|
|
|
|
/* Fixup: bios does not report an EBDA at all. */
|
|
/* Some old Dells seem to need 4k anyhow (bugzilla 2990) */
|
|
if ((ebda_addr == 0) && (lowmem >= 0x9f000))
|
|
lowmem = 0x9f000;
|
|
|
|
/* Paranoia: should never happen, but... */
|
|
if ((lowmem == 0) || (lowmem >= 0x100000))
|
|
lowmem = 0x9f000;
|
|
|
|
/* reserve all memory between lowmem and the 1MB mark */
|
|
reserve_early(lowmem, 0x100000, "BIOS reserved");
|
|
}
|