ACPI: make _OSI(Linux) console messages smarter

If BIOS invokes _OSI(Linux), the kernel response
depends on what the ACPI DMI list knows about the system,
and that is reflectd in dmesg:

1) System unknown to DMI:

ACPI: BIOS _OSI(Linux) query ignored
ACPI: DMI System Vendor: LENOVO
ACPI: DMI Product Name: 7661W1P
ACPI: DMI Product Version: ThinkPad T61
ACPI: DMI Board Name: 7661W1P
ACPI: DMI BIOS Vendor: LENOVO
ACPI: DMI BIOS Date: 10/18/2007
ACPI: Please send DMI info above to linux-acpi@vger.kernel.org
ACPI: If "acpi_osi=Linux" works better, please notify linux-acpi@vger.kernel.org

2) System known to DMI, but effect of OSI(Linux) unknown:

ACPI: DMI detected: Lenovo ThinkPad T61
...
ACPI: BIOS _OSI(Linux) query ignored via DMI
ACPI: If "acpi_osi=Linux" works better, please notify linux-acpi@vger.kernel.org

3) System known to DMI, which disables _OSI(Linux):

ACPI: DMI detected: Lenovo ThinkPad T61
...
ACPI: BIOS _OSI(Linux) query ignored via DMI

4) System known to DMI, which enable _OSI(Linux):

ACPI: DMI detected: Lenovo ThinkPad T61
ACPI: Added _OSI(Linux)
...
ACPI: BIOS _OSI(Linux) query honored via DMI

cmdline overrides take precidence over the built-in
default and the DMI prescribed default.
cmdline "acpi_osi=Linux" results in:

ACPI: BIOS _OSI(Linux) query honored via cmdline

Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index e3c16c9..63f2e6e 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -40,6 +40,7 @@
 #include <acpi/acpi_drivers.h>
 #include <acpi/acpi_numa.h>
 #include <asm/acpi.h>
+#include <linux/dmi.h>
 
 
 #ifdef CONFIG_ACPI
@@ -192,7 +193,9 @@
 #endif /*CONFIG_ACPI_EC*/
 
 extern int acpi_blacklisted(void);
-extern void acpi_bios_year(char *s);
+#ifdef CONFIG_DMI
+extern void acpi_dmi_osi_linux(int enable, const struct dmi_system_id *d);
+#endif
 
 #ifdef CONFIG_ACPI_NUMA
 int acpi_get_pxm(acpi_handle handle);
@@ -226,5 +229,5 @@
 	return 0;
 }
 
-#endif	/* CONFIG_ACPI */
+#endif	/* !CONFIG_ACPI */
 #endif	/*_LINUX_ACPI_H*/