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yaml --- r: 99738 b: refs/heads/master c: 0c51a96 h: refs/heads/master v: v3
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Huang, Ying
authored and
Thomas Gleixner
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Jun 5, 2008
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Original file line number | Diff line number | Diff line change |
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--- | ||
refs/heads/master: ecacf09f7d26b2317e8b1d59fa40f62081fad0bb | ||
refs/heads/master: 0c51a965ed3c44dd50497e74492a015680e49899 |
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#include <linux/kernel.h> | ||
#include <linux/init.h> | ||
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#include <asm/setup.h> | ||
#include <asm/bios_ebda.h> | ||
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#define BIOS_LOWMEM_KILOBYTES 0x413 | ||
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/* | ||
* 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; | ||
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/* 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; | ||
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/* end of low (conventional) memory */ | ||
lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES); | ||
lowmem <<= 10; | ||
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/* start of EBDA area */ | ||
ebda_addr = get_bios_ebda(); | ||
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/* 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; | ||
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/* 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; | ||
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/* Paranoia: should never happen, but... */ | ||
if ((lowmem == 0) || (lowmem >= 0x100000)) | ||
lowmem = 0x9f000; | ||
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/* reserve all memory between lowmem and the 1MB mark */ | ||
reserve_early(lowmem, 0x100000, "BIOS reserved"); | ||
} |
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