x86: reserve end-of-conventional-memory to 1MB on 32-bit

This patch adds explicit detection of the EBDA and reservation
of the rom and adapter address space 0xa0000-0x100000 to the
i386 kernels. Before this patch, the EBDA size was hardcoded
as 4Kb. Also, the reservation of the adapter range was done by
modifying the e820 map which is now not necessary any longer,
and that code is removed from copy_e820_map.

The amount of conventional memory and the start of the EBDA are
detected by reading the BIOS data area directly. Paravirtual
environments do not provide this area, so we bail out early
in that case. They will just have to set up a correct memory
map to start with.

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 20 deletions

diff --git a/arch/x86/kernel/e820_32.c b/arch/x86/kernel/e820_32.c
index 80444c5c9b14..0240cd778365 100644
--- a/arch/x86/kernel/e820_32.c
+++ b/arch/x86/kernel/e820_32.c
@@ -450,38 +450,25 @@ int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
  * thinkpad 560x, for example, does not cooperate with the memory
  * detection code.)
  */
-int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
+int __init copy_e820_map(struct e820entry *biosmap, int nr_map)
 {
         /* Only one memory region (or negative)? Ignore it */
         if (nr_map < 2)
                 return -1;
 
         do {
-                unsigned long long start = biosmap->addr;
-                unsigned long long size = biosmap->size;
-                unsigned long long end = start + size;
-                unsigned long type = biosmap->type;
+                u64 start = biosmap->addr;
+                u64 size = biosmap->size;
+                u64 end = start + size;
+                u32 type = biosmap->type;
 
                 /* Overflow in 64 bits? Ignore the memory map. */
                 if (start > end)
                         return -1;
 
-                /*
-                 * Some BIOSes claim RAM in the 640k - 1M region.
-                 * Not right. Fix it up.
-                 */
-                if (type == E820_RAM) {
-                        if (start < 0x100000ULL && end > 0xA0000ULL) {
-                                if (start < 0xA0000ULL)
-                                        add_memory_region(start, 0xA0000ULL-start, type);
-                                if (end <= 0x100000ULL)
-                                        continue;
-                                start = 0x100000ULL;
-                                size = end - start;
-                        }
-                }
                 add_memory_region(start, size, type);
-        } while (biosmap++,--nr_map);
+        } while (biosmap++, --nr_map);
+
         return 0;
 }