[patch 1/1] Added NO_IOAPIC_CHECK in io_apic_get_unique_id() for ACPI boot

[patch 1/1] Added NO_IOAPIC_CHECK in io_apic_get_unique_id() for ACPI boot

[Natalie.Protasevich]

This patch allows xAPIC systems that don't have serial bus for interrupts delivery to by-pass the check on uniquness of IO-APIC IDs. Some of ES7000's panic failing this unnecessary check. The genapic mechanism has NO_IOAPIC_CHECK flag, which is defined in each subarch. The MP boot utilizes it, but the ACPI boot is missing it.

Signed-off by: Natalie Protasevich  <Natalie.Protasevich@unisys.com>

---


diff -puN arch/i386/kernel/io_apic.c~no-ioapic-check arch/i386/kernel/io_apic.c
--- linux-2.6.13-rc3-mm2/arch/i386/kernel/io_apic.c~no-ioapic-check	2005-05-01 02:15:48.054362032 -0700
+++ linux-2.6.13-rc3-mm2-root/arch/i386/kernel/io_apic.c	2005-05-01 02:28:23.282549896 -0700
@@ -2436,13 +2436,18 @@ int __init io_apic_get_unique_id (int io
 	unsigned long flags;
 	int i = 0;
 
+	/* Don't check I/O APIC IDs for some xAPIC systems.  They have
+	 * no meaning without the serial APIC bus. 
+	 */
+
+	if (NO_IOAPIC_CHECK)
+		return apic_id;
+
 	/*
 	 * The P4 platform supports up to 256 APIC IDs on two separate APIC 
 	 * buses (one for LAPICs, one for IOAPICs), where predecessors only 
 	 * supports up to 16 on one shared APIC bus.
 	 * 
-	 * TBD: Expand LAPIC/IOAPIC support on P4-class systems to take full
-	 *      advantage of new APIC bus architecture.
 	 */
 
 	if (physids_empty(apic_id_map))
_

Re: [patch 1/1] Added NO_IOAPIC_CHECK in io_apic_get_unique_id() for ACPI boot

[Zwane Mwaikambo]

On Sun, 1 May 2005 Natalie.Protasevich@unisys.com wrote:

> This patch allows xAPIC systems that don't have serial bus for 
> interrupts delivery to by-pass the check on uniquness of IO-APIC IDs. 
> Some of ES7000's panic failing this unnecessary check. The genapic 
> mechanism has NO_IOAPIC_CHECK flag, which is defined in each subarch. 
> The MP boot utilizes it, but the ACPI boot is missing it.
> 
> Signed-off by: Natalie Protasevich  <Natalie.Protasevich@unisys.com>

Acked-by: Zwane Mwaikambo <zwane@arm.linux.org.uk>

Thanks Natalie. Andrew although we currently have a lot of patches in 
the same area in your tree and things need settling down, this one looks 
safe to pickup if you'd like to take it in now.