x86, irq: get nr_irqs from madt
Until now, NR_IRQS was derived from black magic defines that had to
be "large enough" to both accomodate NR_CPUS and MAX_NR_IO_APICs.
This resulted in a way too large irq_desc[] array on most x86 systems.
Especially with larger CPU masks, the size of irq_desc can spiral out
of control quickly.
So be smarter about it and use precise allocation instead: determine the
default maximum possible IRQ number from the ACPI MADT. Use a minimum limit
of at least 32 IRQs for broken BIOSes.
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index eb875cd..3e9d163 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -957,6 +957,29 @@
nr_ioapics++;
}
+int get_nr_irqs_via_madt(void)
+{
+ int idx;
+ int nr = 0;
+
+ for (idx = 0; idx < nr_ioapics; idx++) {
+ if (mp_ioapic_routing[idx].gsi_end > nr)
+ nr = mp_ioapic_routing[idx].gsi_end;
+ }
+
+ nr++;
+
+ /* double it for hotplug and msi and nmi */
+ nr <<= 1;
+
+ /* something wrong ? */
+ if (nr < 32)
+ nr = 32;
+
+ return nr;
+
+}
+
static void assign_to_mp_irq(struct mp_config_intsrc *m,
struct mp_config_intsrc *mp_irq)
{
@@ -1254,9 +1277,12 @@
return count;
}
+
+ nr_irqs = get_nr_irqs_via_madt();
+
count =
acpi_table_parse_madt(ACPI_MADT_TYPE_INTERRUPT_OVERRIDE, acpi_parse_int_src_ovr,
- NR_IRQ_VECTORS);
+ nr_irqs);
if (count < 0) {
printk(KERN_ERR PREFIX
"Error parsing interrupt source overrides entry\n");
@@ -1276,7 +1302,7 @@
count =
acpi_table_parse_madt(ACPI_MADT_TYPE_NMI_SOURCE, acpi_parse_nmi_src,
- NR_IRQ_VECTORS);
+ nr_irqs);
if (count < 0) {
printk(KERN_ERR PREFIX "Error parsing NMI SRC entry\n");
/* TBD: Cleanup to allow fallback to MPS */