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authorHuang, Ying <ying.huang@intel.com>2008-06-02 14:26:23 +0800
committerThomas Gleixner <tglx@linutronix.de>2008-06-05 15:10:02 +0200
commit0c51a965ed3c44dd50497e74492a015680e49899 (patch)
treec04c9670b5adecfef995cd1dc49b8c5d9e5e5ed3 /arch/x86/kernel/head.c
parentecacf09f7d26b2317e8b1d59fa40f62081fad0bb (diff)
download96b-common-0c51a965ed3c44dd50497e74492a015680e49899.tar.gz
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 000000000000..e0d0ce58979e
--- /dev/null
+++ b/arch/x86/kernel/head.c
@@ -0,0 +1,55 @@
+#include <linux/kernel.h>
+#include <linux/init.h>
+
+#include <asm/setup.h>
+#include <asm/bios_ebda.h>
+
+#define BIOS_LOWMEM_KILOBYTES 0x413
+
+/*
+ * The BIOS places the EBDA/XBDA at the top of conventional
+ * memory, and usually decreases the reported amount of
+ * conventional memory (int 0x12) too. This also contains a
+ * workaround for Dell systems that neglect to reserve EBDA.
+ * The same workaround also avoids a problem with the AMD768MPX
+ * chipset: reserve a page before VGA to prevent PCI prefetch
+ * into it (errata #56). Usually the page is reserved anyways,
+ * unless you have no PS/2 mouse plugged in.
+ */
+void __init reserve_ebda_region(void)
+{
+ unsigned int lowmem, ebda_addr;
+
+ /* To determine the position of the EBDA and the */
+ /* end of conventional memory, we need to look at */
+ /* the BIOS data area. In a paravirtual environment */
+ /* that area is absent. We'll just have to assume */
+ /* that the paravirt case can handle memory setup */
+ /* correctly, without our help. */
+ if (paravirt_enabled())
+ return;
+
+ /* end of low (conventional) memory */
+ lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
+ lowmem <<= 10;
+
+ /* start of EBDA area */
+ ebda_addr = get_bios_ebda();
+
+ /* Fixup: bios puts an EBDA in the top 64K segment */
+ /* of conventional memory, but does not adjust lowmem. */
+ if ((lowmem - ebda_addr) <= 0x10000)
+ lowmem = ebda_addr;
+
+ /* Fixup: bios does not report an EBDA at all. */
+ /* Some old Dells seem to need 4k anyhow (bugzilla 2990) */
+ if ((ebda_addr == 0) && (lowmem >= 0x9f000))
+ lowmem = 0x9f000;
+
+ /* Paranoia: should never happen, but... */
+ if ((lowmem == 0) || (lowmem >= 0x100000))
+ lowmem = 0x9f000;
+
+ /* reserve all memory between lowmem and the 1MB mark */
+ reserve_early(lowmem, 0x100000, "BIOS reserved");
+}