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authorHuang, Ying2008-06-02 01:26:23 -0500
committerThomas Gleixner2008-06-05 08:10:02 -0500
commit0c51a965ed3c44dd50497e74492a015680e49899 (patch)
treec04c9670b5adecfef995cd1dc49b8c5d9e5e5ed3 /arch/x86/kernel/head.c
parentecacf09f7d26b2317e8b1d59fa40f62081fad0bb (diff)
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x86: extract common part of head32.c and head64.c into head.c
This patch extracts the common part of head32.c and head64.c into head.c. Signed-off-by: Huang Ying <ying.huang@intel.com> Cc: andi@firstfloor.org Cc: mingo@redhat.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel/head.c')
-rw-r--r--arch/x86/kernel/head.c55
1 files changed, 55 insertions, 0 deletions
diff --git a/arch/x86/kernel/head.c b/arch/x86/kernel/head.c
new file mode 100644
index 00000000000..e0d0ce58979
--- /dev/null
+++ b/arch/x86/kernel/head.c
@@ -0,0 +1,55 @@
1#include <linux/kernel.h>
2#include <linux/init.h>
3
4#include <asm/setup.h>
5#include <asm/bios_ebda.h>
6
7#define BIOS_LOWMEM_KILOBYTES 0x413
8
9/*
10 * The BIOS places the EBDA/XBDA at the top of conventional
11 * memory, and usually decreases the reported amount of
12 * conventional memory (int 0x12) too. This also contains a
13 * workaround for Dell systems that neglect to reserve EBDA.
14 * The same workaround also avoids a problem with the AMD768MPX
15 * chipset: reserve a page before VGA to prevent PCI prefetch
16 * into it (errata #56). Usually the page is reserved anyways,
17 * unless you have no PS/2 mouse plugged in.
18 */
19void __init reserve_ebda_region(void)
20{
21 unsigned int lowmem, ebda_addr;
22
23 /* To determine the position of the EBDA and the */
24 /* end of conventional memory, we need to look at */
25 /* the BIOS data area. In a paravirtual environment */
26 /* that area is absent. We'll just have to assume */
27 /* that the paravirt case can handle memory setup */
28 /* correctly, without our help. */
29 if (paravirt_enabled())
30 return;
31
32 /* end of low (conventional) memory */
33 lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
34 lowmem <<= 10;
35
36 /* start of EBDA area */
37 ebda_addr = get_bios_ebda();
38
39 /* Fixup: bios puts an EBDA in the top 64K segment */
40 /* of conventional memory, but does not adjust lowmem. */
41 if ((lowmem - ebda_addr) <= 0x10000)
42 lowmem = ebda_addr;
43
44 /* Fixup: bios does not report an EBDA at all. */
45 /* Some old Dells seem to need 4k anyhow (bugzilla 2990) */
46 if ((ebda_addr == 0) && (lowmem >= 0x9f000))
47 lowmem = 0x9f000;
48
49 /* Paranoia: should never happen, but... */
50 if ((lowmem == 0) || (lowmem >= 0x100000))
51 lowmem = 0x9f000;
52
53 /* reserve all memory between lowmem and the 1MB mark */
54 reserve_early(lowmem, 0x100000, "BIOS reserved");
55}