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Commit 71f521bb authored by Yinghai Lu's avatar Yinghai Lu Committed by Ingo Molnar
Browse files

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: default avatarYinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent a84488c2

arch/x86/kernel/acpi/boot.c

+28 −2
Original line number Diff line number Diff line
@@ -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 */

include/asm-x86/mpspec.h

+1 −0
Original line number Diff line number Diff line
@@ -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);