ACPICA: Ignore ACPI table signature for Load() operator

upstream bc45b1d39a925b56796bebf8a397a0491489d85c

Without this patch booting with acpi_osi="!Windows 2006" is required
for several machines to function properly with cpufreq
due to failure to load a Vista specific table with a bad signature.

Only "SSDT" is acceptable to the ACPI spec, but tables are
seen with OEMx and null sigs. Therefore, signature validation
is worthless.  Apparently MS ACPI accepts such signatures, ACPICA
must be compatible.

http://bugzilla.kernel.org/show_bug.cgi?id=9919
http://bugzilla.kernel.org/show_bug.cgi?id=10383
http://bugzilla.kernel.org/show_bug.cgi?id=10454
https://bugzilla.novell.com/show_bug.cgi?id=396311

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/acpi/tables/tbinstal.c b/drivers/acpi/tables/tbinstal.c
index 3bc0c67a9283e395943ee0e42c5db83b3c43f134..225e88c4ade2362deb67d1db2247336f1dbc7818 100644 (file)
--- a/drivers/acpi/tables/tbinstal.c
+++ b/drivers/acpi/tables/tbinstal.c
@@ -123,17 +123,13 @@ acpi_tb_add_table(struct acpi_table_desc *table_desc,
                }
        }
 
-       /* The table must be either an SSDT or a PSDT or an OEMx */
-
-       if ((!ACPI_COMPARE_NAME(table_desc->pointer->signature, ACPI_SIG_PSDT))
-           &&
-           (!ACPI_COMPARE_NAME(table_desc->pointer->signature, ACPI_SIG_SSDT))
-           && (strncmp(table_desc->pointer->signature, "OEM", 3))) {
-               ACPI_ERROR((AE_INFO,
-                           "Table has invalid signature [%4.4s], must be SSDT, PSDT or OEMx",
-                           table_desc->pointer->signature));
-               return_ACPI_STATUS(AE_BAD_SIGNATURE);
-       }
+       /*
+        * Originally, we checked the table signature for "SSDT" or "PSDT" here.
+        * Next, we added support for OEMx tables, signature "OEM".
+        * Valid tables were encountered with a null signature, so we've just
+        * given up on validating the signature, since it seems to be a waste
+        * of code. The original code was removed (05/2008).
+        */
 
        (void)acpi_ut_acquire_mutex(ACPI_MTX_TABLES);