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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>
This commit is contained in:
Len Brown 2007-03-11 03:26:14 -04:00
parent be521466fe
commit a1fdcc0d27
2 changed files with 58 additions and 5 deletions
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6
Documentation/kernel-parameters.txt
View File

@ -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

57
drivers/acpi/tables.c
View File

@ -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@vger.kernel.org\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);