panic: Add taint flag TAINT_FIRMWARE_WORKAROUND ('I')

This taint flag will initially be used when warning about invalid ACPI
DMAR tables.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

Documentation/oops-tracing.txt

@@ -260,6 +260,9 @@ characters, each representing a particular tainted value.
 
  11: 'C' if a staging driver has been loaded.
 
+ 12: 'I' if the kernel is working around a severe bug in the platform
+     firmware (BIOS or similar).
+
 The primary reason for the 'Tainted: ' string is to tell kernel
 debuggers if this is a clean kernel or if anything unusual has
 occurred.  Tainting is permanent: even if an offending module is

include/linux/kernel.h

@@ -344,6 +344,7 @@ extern enum system_states {
 #define TAINT_OVERRIDDEN_ACPI_TABLE	8
 #define TAINT_WARN			9
 #define TAINT_CRAP			10
+#define TAINT_FIRMWARE_WORKAROUND	11
 
 extern void dump_stack(void) __cold;
 

kernel/panic.c

@@ -178,6 +178,7 @@ static const struct tnt tnts[] = {
 	{ TAINT_OVERRIDDEN_ACPI_TABLE,	'A', ' ' },
 	{ TAINT_WARN,			'W', ' ' },
 	{ TAINT_CRAP,			'C', ' ' },
+	{ TAINT_FIRMWARE_WORKAROUND,	'I', ' ' },
 };
 
 /**
@@ -194,6 +195,7 @@ static const struct tnt tnts[] = {
  *  'A' - ACPI table overridden.
  *  'W' - Taint on warning.
  *  'C' - modules from drivers/staging are loaded.
+ *  'I' - Working around severe firmware bug.
  *
  *	The string is overwritten by the next call to print_tainted().
  */