IOAPIC not disabled on shutdown of X86_UP_IOAPIC kernel 2.4.18

[Philip Thomas]

The following patch causes the IOAPIC to be disabled during shutdown of
kernels compiled with either the CONFIG_SMP or the CONFIG_X86_UP_IOAPIC
options (either of which causes the IOAPIC to be initialized).
Previously, the IOAPIC was disabled only during shutdown of CONFIG_SMP
kernels, and not CONFIG_X86_UP_IOAPIC kernels.  This caused unexpected
IRQ errors on warm boot of CONFIG_X86_UP_IOAPIC kernel because BIOS did
not reset the IOAPIC.

Phil

--- arch/i386/kernel/process.c.orig	2003-06-03 17:03:28.000000000
-0700
+++ arch/i386/kernel/process.c	2003-06-03 17:03:41.000000000 -0700
@@ -399,11 +399,17 @@
 		__asm__ __volatile__ ("hlt");
 	}
 	/*
-	 * Stop all CPUs and turn off local APICs and the IO-APIC, so
+	 * Stop all CPUs and turn off local APICs, so
 	 * other OSs see a clean IRQ state.
 	 */
 	if (!netdump_func)
 		smp_send_stop();
+#endif
+
+#if CONFIG_X86_IOAPIC
+	/*
+	 * Turn off the IO-APIC, so other OSs see a clean IRQ state.
+	 */
 	disable_IO_APIC();
 #endif