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x86: cleanup e820_setup_gap(), add e820_search_gap(), v2

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This is a preparatory patch for the next patch in series.
Moves some code from e820_setup_gap to a new function e820_search_gap.
This patch is a part of a bug fix where we walk the ACPI table to calculate
a gap for PCI optional devices.

v1->v2: Patch on top of tip/master.
	Fixes a bug introduced in the last patch about the typeof "last".
	Also the new function e820_search_gap now returns if we found a gap in
	e820_map.

Signed-off-by: Alok N Kataria <akataria@vmware.com>
Cc: lenb@kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Alok Kataria 2008-06-24 11:48:30 -07:00 committed by Ingo Molnar
parent c987d12f84
commit 3381959da5
2 changed files with 30 additions and 15 deletions
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43
arch/x86/kernel/e820.c
View File

@ -488,26 +488,22 @@ void __init update_e820(void)
}
/*
* Search for the biggest gap in the low 32 bits of the e820
* memory space. We pass this space to PCI to assign MMIO resources
* for hotplug or unconfigured devices in.
* Hopefully the BIOS let enough space left.
* Search for a gap in the e820 memory space from start_addr to 2^32.
*/
__init void e820_setup_gap(void)
__init int e820_search_gap(unsigned long *gapstart, unsigned long *gapsize,
unsigned long start_addr)
{
unsigned long gapstart, gapsize, round;
unsigned long long last;
int i;
unsigned long long last = 0x100000000ull;
int i = e820.nr_map;
int found = 0;
last = 0x100000000ull;
gapstart = 0x10000000;
gapsize = 0x400000;
i = e820.nr_map;
while (--i >= 0) {
unsigned long long start = e820.map[i].addr;
unsigned long long end = start + e820.map[i].size;
if (end < start_addr)
continue;
/*
* Since "last" is at most 4GB, we know we'll
* fit in 32 bits if this condition is true
@ -515,15 +511,32 @@ __init void e820_setup_gap(void)
if (last > end) {
unsigned long gap = last - end;
if (gap > gapsize) {
gapsize = gap;
gapstart = end;
if (gap >= *gapsize) {
*gapsize = gap;
*gapstart = end;
found = 1;
}
}
if (start < last)
last = start;
}
return found;
}
/*
* Search for the biggest gap in the low 32 bits of the e820
* memory space. We pass this space to PCI to assign MMIO resources
* for hotplug or unconfigured devices in.
* Hopefully the BIOS let enough space left.
*/
__init void e820_setup_gap(void)
{
unsigned long gapstart, gapsize, round;
int found;
gapstart = 0x10000000;
gapsize = 0x400000;
found = e820_search_gap(&gapstart, &gapsize, 0);
#ifdef CONFIG_X86_64
if (!found) {

2
include/asm-x86/e820.h
View File

@ -71,6 +71,8 @@ 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);
struct setup_data;
extern void parse_e820_ext(struct setup_data *data, unsigned long pa_data);