ACPI, x86: Extended error log driver for x86 platform

This H/W error log driver (a.k.a eMCA driver) is implemented based on
http://www.intel.com/content/www/us/en/architecture-and-technology/enhanced-mca-logging-xeon-paper.html

After errors are captured, more detailed platform specific information
can be got via this new enhanced H/W error log driver. Most notably we
can track memory errors back to the DIMM slot silk screen label.

Signed-off-by: Chen, Gong <gong.chen@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 6efe2ac..252f0e8 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -372,4 +372,23 @@
 
 source "drivers/acpi/apei/Kconfig"
 
+config ACPI_EXTLOG
+	tristate "Extended Error Log support"
+	depends on X86_MCE && ACPI_APEI
+	default n
+	help
+	  Certain usages such as Predictive Failure Analysis (PFA) require
+	  more information about the error than what can be described in
+	  processor machine check banks. Most server processors log
+	  additional information about the error in processor uncore
+	  registers. Since the addresses and layout of these registers vary
+	  widely from one processor to another, system software cannot
+	  readily make use of them. To complicate matters further, some of
+	  the additional error information cannot be constructed without
+	  detailed knowledge about platform topology.
+
+	  Enhanced MCA Logging allows firmware to provide additional error
+	  information to system software, synchronous with MCE or CMCI. This
+	  driver adds support for that functionality.
+
 endif	# ACPI