[PATCH] linux-2.4.22-pre3_clear-smi-fix_A0

[john stultz]

Marcelo, all,

	Some of our more recent hardware requires that SMIs are routed through
the IOAPIC, thus when we clear_IO_APIC() at boot time, we clear the BIOS
initialized SMI pin. This basically clobbers the SMI, which can cause
problems with console redirection as well keeping us from being able to
transition into full ACPI mode. 

This patch (back ported from 2.5) simply reads the apic entry in
clear_IO_APIC to make sure the delivery_mode isn't dest_SMI. If it is,
we leave the apic entry alone and return.

With this patch, booting with full ACPI works and SMIs function
properly. 

Please apply

thanks
-john

diff -Nru a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
--- a/arch/i386/kernel/io_apic.c	Mon Jul  7 14:00:31 2003
+++ b/arch/i386/kernel/io_apic.c	Mon Jul  7 14:00:31 2003
@@ -169,6 +169,14 @@
 {
 	struct IO_APIC_route_entry entry;
 	unsigned long flags;
+	
+	/* Check delivery_mode to be sure we're not clearing an SMI pin */
+	spin_lock_irqsave(&ioapic_lock, flags);
+	*(((int*)&entry) + 0) = io_apic_read(apic, 0x10 + 2 * pin);
+	*(((int*)&entry) + 1) = io_apic_read(apic, 0x11 + 2 * pin);
+	spin_unlock_irqrestore(&ioapic_lock, flags);
+	if (entry.delivery_mode == dest_SMI)
+		return;
 
 	/*
 	 * Disable it in the IO-APIC irq-routing table: