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Subject[PATCH] x86: make e820_update_range to handle small range update

Impact: enhance to handle more case.

try to handle new range could be covered by one entry.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
arch/x86/kernel/e820.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
Index: linux-2.6/arch/x86/kernel/e820.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/e820.c
+++ linux-2.6/arch/x86/kernel/e820.c
@@ -427,6 +427,7 @@ static u64 __init __e820_update_range(st
u64 size, unsigned old_type,
unsigned new_type)
{
+ u64 end;
unsigned int i;
u64 real_updated_size = 0;

@@ -435,21 +436,35 @@ static u64 __init __e820_update_range(st
if (size > (ULLONG_MAX - start))
size = ULLONG_MAX - start;

+ end = start + size;
for (i = 0; i < e820x->nr_map; i++) {
struct e820entry *ei = &e820x->map[i];
u64 final_start, final_end;
+ u64 ei_end;
+
if (ei->type != old_type)
continue;
- /* totally covered? */
- if (ei->addr >= start &&
- (ei->addr + ei->size) <= (start + size)) {
+
+ ei_end = ei->addr + ei->size;
+ /* totally covered by new range? */
+ if (ei->addr >= start && ei_end <= end) {
ei->type = new_type;
real_updated_size += ei->size;
continue;
}
+
+ /* new range is totally covered? */
+ if (ei->addr < start && ei_end > end) {
+ __e820_add_region(e820x, start, size, new_type);
+ __e820_add_region(e820x, end, ei_end - end, ei->type);
+ ei->size = start - ei->addr;
+ real_updated_size += size;
+ continue;
+ }
+
/* partially covered */
final_start = max(start, ei->addr);
- final_end = min(start + size, ei->addr + ei->size);
+ final_end = min(end, ei_end);
if (final_start >= final_end)
continue;


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