ACPI: Add support to parse 2nd MADT

When a BIOS bug presents multiple APIC/MADTs, Linux currently uses the 1st and ignores the 2nd. But some machines work better if we use the 2nd. http://bugzilla.kernel.org/show_bug.cgi?id=7465 Add a warning and boot parameter "acpi_apic_instance=2" to allow parsing the 2nd. No change to default behaviour in this patch. Signed-off-by: Len Brown <len.brown@intel.com>

ACPI: Add support to parse 2nd MADT
When a BIOS bug presents multiple APIC/MADTs, Linux currently uses the 1st and ignores the 2nd. But some machines work better if we use the 2nd. http://bugzilla.kernel.org/show_bug.cgi?id=7465 Add a warning and boot parameter "acpi_apic_instance=2" to allow parsing the 2nd. No change to default behaviour in this patch. Signed-off-by: Len Brown <len.brown@intel.com>
Len Brown
1 parent be521466fe
Showing 2 changed files with 58 additions and 5 deletions Side-by-side Diff
Documentation/kernel-parameters.txt
drivers/acpi/tables.c
@@ -138,6 +138,12 @@
  
 			See also Documentation/pm.txt, pci=noacpi
  
+	acpi_apic_instance=	[ACPI, IOAPIC]
+			Format: <int>
+			2: use 2nd APIC table, if available
+			1,0: use 1st APIC table
+			default: 0
+
 	acpi_sleep=	[HW,ACPI] Sleep options
 			Format: { s3_bios, s3_mode }
 			See Documentation/power/video.txt
@@ -42,7 +42,9 @@
  
 static struct acpi_table_desc initial_tables[ACPI_MAX_TABLES] __initdata;
  
-void acpi_table_print_madt_entry(struct acpi_subtable_header * header)
+static int acpi_apic_instance __initdata;
+
+void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
 {
 	if (!header)
 		return;
@@ -183,8 +185,10 @@
 	if (!handler)
 		return -EINVAL;
  
-	/* Locate the table (if exists). There should only be one. */
-	acpi_get_table(id, 0, &table_header);
+	if (strncmp(id, ACPI_SIG_MADT, 4) == 0)
+		acpi_get_table(id, acpi_apic_instance, &table_header);
+	else
+		acpi_get_table(id, 0, &table_header);
  
 	if (!table_header) {
 		printk(KERN_WARNING PREFIX "%4.4s not present\n", id);
  
@@ -237,10 +241,15 @@
 int __init acpi_table_parse(char *id, acpi_table_handler handler)
 {
 	struct acpi_table_header *table = NULL;
+
 	if (!handler)
 		return -EINVAL;
  
-	acpi_get_table(id, 0, &table);
+	if (strncmp(id, ACPI_SIG_MADT, 4) == 0)
+		acpi_get_table(id, acpi_apic_instance, &table);
+	else
+		acpi_get_table(id, 0, &table);
+
 	if (table) {
 		handler(table);
 		return 0;
@@ -248,6 +257,31 @@
 		return 1;
 }
  
+/* 
+ * The BIOS is supposed to supply a single APIC/MADT,
+ * but some report two.  Provide a knob to use either.
+ * (don't you wish instance 0 and 1 were not the same?)
+ */
+static void __init check_multiple_madt(void)
+{
+	struct acpi_table_header *table = NULL;
+
+	acpi_get_table(ACPI_SIG_MADT, 2, &table);
+	if (table) {
+		printk(KERN_WARNING PREFIX
+		       "BIOS bug: multiple APIC/MADT found,"
+		       " using %d\n", acpi_apic_instance);
+		printk(KERN_WARNING PREFIX
+		       "If \"acpi_apic_instance=%d\" works better, "
+		       "notify linux-acpi@vger.kernel.org\n",
+		       acpi_apic_instance ? 0 : 2);
+
+	} else
+		acpi_apic_instance = 0;
+
+	return;
+}
+
 /*
  * acpi_table_init()
  *
  
  
@@ -257,10 +291,23 @@
  * result: sdt_entry[] is initialized
  */
  
-
 int __init acpi_table_init(void)
 {
 	acpi_initialize_tables(initial_tables, ACPI_MAX_TABLES, 0);
+	check_multiple_madt();
 	return 0;
 }
+
+static int __init acpi_parse_apic_instance(char *str)
+{
+
+	acpi_apic_instance = simple_strtoul(str, NULL, 0);
+
+	printk(KERN_NOTICE PREFIX "Shall use APIC/MADT table %d\n",
+	       acpi_apic_instance);
+
+	return 0;
+}
+
+early_param("acpi_apic_instance", acpi_parse_apic_instance);
...	...	@@ -138,6 +138,12 @@
138	138
139	139	See also Documentation/pm.txt, pci=noacpi
140	140
	141	+ acpi_apic_instance= [ACPI, IOAPIC]
	142	+ Format: <int>
	143	+ 2: use 2nd APIC table, if available
	144	+ 1,0: use 1st APIC table
	145	+ default: 0
	146	+
141	147	acpi_sleep= [HW,ACPI] Sleep options
142	148	Format: { s3_bios, s3_mode }
143	149	See Documentation/power/video.txt
...	...	@@ -42,7 +42,9 @@
42	42
43	43	static struct acpi_table_desc initial_tables[ACPI_MAX_TABLES] __initdata;
44	44
45		-void acpi_table_print_madt_entry(struct acpi_subtable_header * header)
	45	+static int acpi_apic_instance __initdata;
	46	+
	47	+void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
46	48	{
47	49	if (!header)
48	50	return;
...	...	@@ -183,8 +185,10 @@
183	185	if (!handler)
184	186	return -EINVAL;
185	187
186		- /* Locate the table (if exists). There should only be one. */
187		- acpi_get_table(id, 0, &table_header);
	188	+ if (strncmp(id, ACPI_SIG_MADT, 4) == 0)
	189	+ acpi_get_table(id, acpi_apic_instance, &table_header);
	190	+ else
	191	+ acpi_get_table(id, 0, &table_header);
188	192
189	193	if (!table_header) {
190	194	printk(KERN_WARNING PREFIX "%4.4s not present\n", id);
191	195
...	...	@@ -237,10 +241,15 @@
237	241	int __init acpi_table_parse(char *id, acpi_table_handler handler)
238	242	{
239	243	struct acpi_table_header *table = NULL;
	244	+
240	245	if (!handler)
241	246	return -EINVAL;
242	247
243		- acpi_get_table(id, 0, &table);
	248	+ if (strncmp(id, ACPI_SIG_MADT, 4) == 0)
	249	+ acpi_get_table(id, acpi_apic_instance, &table);
	250	+ else
	251	+ acpi_get_table(id, 0, &table);
	252	+
244	253	if (table) {
245	254	handler(table);
246	255	return 0;
...	...	@@ -248,6 +257,31 @@
248	257	return 1;
249	258	}
250	259
	260	+/*
	261	+ * The BIOS is supposed to supply a single APIC/MADT,
	262	+ * but some report two. Provide a knob to use either.
	263	+ * (don't you wish instance 0 and 1 were not the same?)
	264	+ */
	265	+static void __init check_multiple_madt(void)
	266	+{
	267	+ struct acpi_table_header *table = NULL;
	268	+
	269	+ acpi_get_table(ACPI_SIG_MADT, 2, &table);
	270	+ if (table) {
	271	+ printk(KERN_WARNING PREFIX
	272	+ "BIOS bug: multiple APIC/MADT found,"
	273	+ " using %d\n", acpi_apic_instance);
	274	+ printk(KERN_WARNING PREFIX
	275	+ "If \"acpi_apic_instance=%d\" works better, "
	276	+ "notify linux-acpi@vger.kernel.org\n",
	277	+ acpi_apic_instance ? 0 : 2);
	278	+
	279	+ } else
	280	+ acpi_apic_instance = 0;
	281	+
	282	+ return;
	283	+}
	284	+
251	285	/*
252	286	* acpi_table_init()
253	287	*
254	288
255	289
...	...	@@ -257,10 +291,23 @@
257	291	* result: sdt_entry[] is initialized
258	292	*/
259	293
260		-
261	294	int __init acpi_table_init(void)
262	295	{
263	296	acpi_initialize_tables(initial_tables, ACPI_MAX_TABLES, 0);
	297	+ check_multiple_madt();
264	298	return 0;
265	299	}
	300	+
	301	+static int __init acpi_parse_apic_instance(char *str)
	302	+{
	303	+
	304	+ acpi_apic_instance = simple_strtoul(str, NULL, 0);
	305	+
	306	+ printk(KERN_NOTICE PREFIX "Shall use APIC/MADT table %d\n",
	307	+ acpi_apic_instance);
	308	+
	309	+ return 0;
	310	+}
	311	+
	312	+early_param("acpi_apic_instance", acpi_parse_apic_instance);