From 0c51a965ed3c44dd50497e74492a015680e49899 Mon Sep 17 00:00:00 2001 From: Huang, Ying Date: Mon, 2 Jun 2008 14:26:23 +0800 Subject: 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 Cc: andi@firstfloor.org Cc: mingo@redhat.com Signed-off-by: Thomas Gleixner --- arch/x86/kernel/head.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 arch/x86/kernel/head.c (limited to 'arch/x86/kernel/head.c') 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 @@ +#include +#include + +#include +#include + +#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"); +} -- cgit v1.2.3-54-g00ecf