From: Len Brown <len.brown@xxxxxxxxx> 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@xxxxxxxxx> --- Documentation/kernel-parameters.txt | 6 ++++ drivers/acpi/tables.c | 57 +++++++++++++++++++++++++++++++--- 2 files changed, 58 insertions(+), 5 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 856c8b1..22c6b8c 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -138,6 +138,12 @@ and is between 256 and 4096 characters. It is defined in the file 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 diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index 849e2c3..c341918 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c @@ -42,7 +42,9 @@ static char *mps_inti_flags_trigger[] = { "dfl", "edge", "res", "level" }; 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 @@ acpi_table_parse_entries(char *id, 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 @@ acpi_table_parse_madt(enum acpi_madt_type id, 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 @@ int __init acpi_table_parse(char *id, acpi_table_handler handler) 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@xxxxxxxxxxxxxxx\n", + acpi_apic_instance ? 0 : 2); + + } else + acpi_apic_instance = 0; + + return; +} + /* * acpi_table_init() * @@ -257,9 +291,22 @@ int __init acpi_table_parse(char *id, acpi_table_handler handler) * 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); -- 1.5.0.3.316.gbd1fc - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
