[Xen-changelog] [xen-unstable] IO-APIC: Prevent using EOI broadcast suppression if user specified ioapic_ack=new on the command line.

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
# Date 1329991127 0
# Node ID 9bf3ec036bef2b67338bf5685423e26de69bd031
# Parent  a4d93d0e0df2fafe5b3e2dab3e34799498a875e2
IO-APIC: Prevent using EOI broadcast suppression if user specified 
ioapic_ack=new on the command line.

Currently, if EOI broadcast suppression is advertised on the BSP
LAPIC, Xen will discard any user specified option regarding IO-APIC
ack mode.

This patch introduces a check which prevents EOI Broadcast suppression
from forcing the IO-APIC ack mode to old if the user has explicitly
asked for the new ack mode on the command line.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Committed-by: Keir Fraser <keir@xxxxxxx>
---


diff -r a4d93d0e0df2 -r 9bf3ec036bef xen/arch/x86/apic.c
--- a/xen/arch/x86/apic.c       Wed Feb 22 14:33:24 2012 +0000
+++ b/xen/arch/x86/apic.c       Thu Feb 23 09:58:47 2012 +0000
@@ -424,9 +424,15 @@
      */
     if ( reg0 & APIC_LVR_DIRECTED_EOI )
     {
-        ioapic_ack_new = 0;
-        directed_eoi_enabled = 1;
-        printk("Enabled directed EOI with ioapic_ack_old on!\n");
+        if ( ioapic_ack_new == 1 && ioapic_ack_forced == 1 )
+            printk("Not enabling directed EOI because ioapic_ack_new has been "
+                   "forced on the command line\n");
+        else
+        {
+            ioapic_ack_new = 0;
+            directed_eoi_enabled = 1;
+            printk("Enabled directed EOI with ioapic_ack_old on!\n");
+        }
     }
 
     /*
diff -r a4d93d0e0df2 -r 9bf3ec036bef xen/arch/x86/io_apic.c
--- a/xen/arch/x86/io_apic.c    Wed Feb 22 14:33:24 2012 +0000
+++ b/xen/arch/x86/io_apic.c    Thu Feb 23 09:58:47 2012 +0000
@@ -44,6 +44,7 @@
 
 bool_t __read_mostly skip_ioapic_setup;
 bool_t __read_mostly ioapic_ack_new = 1;
+bool_t __read_mostly ioapic_ack_forced = 0;
 
 #ifndef sis_apic_bug
 /*
@@ -1543,9 +1544,15 @@
 static void __init setup_ioapic_ack(char *s)
 {
     if ( !strcmp(s, "old") )
+    {
         ioapic_ack_new = 0;
+        ioapic_ack_forced = 1;
+    }
     else if ( !strcmp(s, "new") )
+    {
         ioapic_ack_new = 1;
+        ioapic_ack_forced = 1;
+    }
     else
         printk("Unknown ioapic_ack value specified: '%s'\n", s);
 }
diff -r a4d93d0e0df2 -r 9bf3ec036bef xen/include/asm-x86/io_apic.h
--- a/xen/include/asm-x86/io_apic.h     Wed Feb 22 14:33:24 2012 +0000
+++ b/xen/include/asm-x86/io_apic.h     Thu Feb 23 09:58:47 2012 +0000
@@ -180,6 +180,7 @@
 /* 1 if "noapic" boot option passed */
 extern bool_t skip_ioapic_setup;
 extern bool_t ioapic_ack_new;
+extern bool_t ioapic_ack_forced;
 
 #ifdef CONFIG_ACPI_BOOT
 extern int io_apic_get_unique_id (int ioapic, int apic_id);

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