[Xen-changelog] [xen-unstable] x86: Handle 'self-IPI' on legacy UP systems with no APIC.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1189442998 -3600
# Node ID aaae02dbe2697f0103adf5dd396b6a80eef420dc
# Parent  1c85fe14169f4de73be50604cb6d5b50bec48e6b
x86: Handle 'self-IPI' on legacy UP systems with no APIC.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 xen/arch/x86/smp.c |   13 +++++++++++++
 1 files changed, 13 insertions(+)

diff -r 1c85fe14169f -r aaae02dbe269 xen/arch/x86/smp.c
--- a/xen/arch/x86/smp.c        Mon Sep 10 16:51:20 2007 +0100
+++ b/xen/arch/x86/smp.c        Mon Sep 10 17:49:58 2007 +0100
@@ -279,6 +279,19 @@ int on_selected_cpus(
 
     ASSERT(local_irq_is_enabled());
 
+    /* Legacy UP system with no APIC to deliver IPIs? */
+    if ( unlikely(!cpu_has_apic) )
+    {
+        ASSERT(num_online_cpus() == 1);
+        if ( cpu_isset(0, selected) )
+        {
+            local_irq_disable();
+            func(info);
+            local_irq_enable();
+        }
+        return 0;
+    }
+
     if ( nr_cpus == 0 )
         return 0;
 

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