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 eb875cdc7367c3aee3fcb285606c1e993cc808af..3e9d163fd92f5e91565e70f4168b50217ed5791f 100644 (file)
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -957,6 +957,29 @@ void __init mp_register_ioapic(int id, u32 address, u32 gsi_base)
        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 @@ static int __init acpi_parse_madt_ioapic_entries(void)
                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 @@ static int __init acpi_parse_madt_ioapic_entries(void)
 
        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 */

diff --git a/include/asm-x86/mpspec.h b/include/asm-x86/mpspec.h
index be2241a818f1e536eda377b4ceb94d04ae2b171c..a0748021250b7306c11a425d5511c7051f273342 100644 (file)
--- a/include/asm-x86/mpspec.h
+++ b/include/asm-x86/mpspec.h
@@ -60,6 +60,7 @@ extern void mp_override_legacy_irq(u8 bus_irq, u8 polarity, u8 trigger,
                                   u32 gsi);
 extern void mp_config_acpi_legacy_irqs(void);
 extern int mp_register_gsi(u32 gsi, int edge_level, int active_high_low);
+extern int get_nr_irqs_via_madt(void);
 #ifdef CONFIG_X86_IO_APIC
 extern int mp_config_acpi_gsi(unsigned char number, unsigned int devfn, u8 pin,
                                u32 gsi, int triggering, int polarity);