ACPI: tables: complete searching upon RSDP w/ bad checksum.

ACPI tables follow a tree structure in memory.
The root of the tree is the RSDP (Root System Description Pointer).

To find the RSDP, the OS searches for the signature "RSD PTR "
in well known physical memory locations.  Then the OS computes
a table checksum to verify that the signature is really part
of a valid table header.

Some systems have a proper signature but an invalid checksum;
followed elsewhere by a proper signature with valid checksum.

http://bugzilla.kernel.org/show_bug.cgi?id=9444

The Linux RSDP scanning code bailed out on those systems
and as a result they booted with ACPI disabled.

Fix this by deleting the Linux RSDP scanning code and
plugging in the ACPICA RSDP scanning code.

Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 1 insertions, 41 deletions

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 0ca27c7b0e8d..719c74b0141a 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -581,25 +581,6 @@ int acpi_unregister_ioapic(acpi_handle handle, u32 gsi_base)
 
 EXPORT_SYMBOL(acpi_unregister_ioapic);
 
-static unsigned long __init
-acpi_scan_rsdp(unsigned long start, unsigned long length)
-{
-	unsigned long offset = 0;
-	unsigned long sig_len = sizeof("RSD PTR ") - 1;
-
-	/*
-	 * Scan all 16-byte boundaries of the physical memory region for the
-	 * RSDP signature.
-	 */
-	for (offset = 0; offset < length; offset += 16) {
-		if (strncmp((char *)(phys_to_virt(start) + offset), "RSD PTR ", sig_len))
-			continue;
-		return (start + offset);
-	}
-
-	return 0;
-}
-
 static int __init acpi_parse_sbf(struct acpi_table_header *table)
 {
 	struct acpi_table_boot *sb;
@@ -742,27 +723,6 @@ static int __init acpi_parse_fadt(struct acpi_table_header *table)
 	return 0;
 }
 
-unsigned long __init acpi_find_rsdp(void)
-{
-	unsigned long rsdp_phys = 0;
-
-	if (efi_enabled) {
-		if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
-			return efi.acpi20;
-		else if (efi.acpi != EFI_INVALID_TABLE_ADDR)
-			return efi.acpi;
-	}
-	/*
-	 * Scan memory looking for the RSDP signature. First search EBDA (low
-	 * memory) paragraphs and then search upper memory (E0000-FFFFF).
-	 */
-	rsdp_phys = acpi_scan_rsdp(0, 0x400);
-	if (!rsdp_phys)
-		rsdp_phys = acpi_scan_rsdp(0xE0000, 0x20000);
-
-	return rsdp_phys;
-}
-
 #ifdef	CONFIG_X86_LOCAL_APIC
 /*
  * Parse LAPIC entries in MADT
diff --git a/arch/x86/kernel/srat_32.c b/arch/x86/kernel/srat_32.c
index 2a8713ec0f9a..b3b2c95f19d3 100644
--- a/arch/x86/kernel/srat_32.c
+++ b/arch/x86/kernel/srat_32.c
@@ -276,7 +276,7 @@ int __init get_memcfg_from_srat(void)
 	int tables = 0;
 	int i = 0;
 
-	rsdp_address = acpi_find_rsdp();
+	rsdp_address = acpi_os_get_root_pointer();
 	if (!rsdp_address) {
 		printk("%s: System description tables not found\n",
 		       __FUNCTION__);