x86: add e820_remove_range

... so could add real hole in e820

agp check is using request_mem_region, and could fail if e820 is reserved...

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 35 insertions, 0 deletions

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 7b613d2efb04..e285ea38c8e5 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -429,6 +429,41 @@ u64 __init e820_update_range(u64 start, u64 size, unsigned old_type,
         return real_updated_size;
 }
 
+/* make e820 not cover the range */
+u64 __init e820_remove_range(u64 start, u64 size, unsigned old_type,
+                             int checktype)
+{
+        int i;
+        u64 real_removed_size = 0;
+
+        for (i = 0; i < e820.nr_map; i++) {
+                struct e820entry *ei = &e820.map[i];
+                u64 final_start, final_end;
+
+                if (checktype && ei->type != old_type)
+                        continue;
+                /* totally covered? */
+                if (ei->addr >= start &&
+                    (ei->addr + ei->size) <= (start + size)) {
+                        real_removed_size += ei->size;
+                        memset(ei, 0, sizeof(struct e820entry));
+                        continue;
+                }
+                /* partially covered */
+                final_start = max(start, ei->addr);
+                final_end = min(start + size, ei->addr + ei->size);
+                if (final_start >= final_end)
+                        continue;
+                real_removed_size += final_end - final_start;
+
+                ei->size -= final_end - final_start;
+                if (ei->addr < final_start)
+                        continue;
+                ei->addr = final_end;
+        }
+        return real_removed_size;
+}
+
 void __init update_e820(void)
 {
         int nr_map;