[Xen-changelog] Allow IRQ balancing to be disabled with 'noirqbalance'

[Xen patchbot -2.0-testing <patchbot-2.0-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 0d3eaf70dedfdde3acea9f8c0cf7ee7416f04922
# Parent  7dc965fa6cce27a8d64bc018b06c42f231096cf4

Allow IRQ balancing to be disabled with 'noirqbalance'
boot parameter.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>

diff -r 7dc965fa6cce -r 0d3eaf70dedf xen/arch/x86/irq.c
--- a/xen/arch/x86/irq.c        Thu Jul 14 08:50:01 2005
+++ b/xen/arch/x86/irq.c        Thu Jul 14 10:34:57 2005
@@ -6,12 +6,17 @@
  */
 
 #include <xen/config.h>
+#include <xen/init.h>
 #include <xen/errno.h>
 #include <xen/event.h>
 #include <xen/irq.h>
 #include <xen/perfc.h>
 #include <xen/sched.h>
 #include <asm/smpboot.h>
+
+/* opt_noirqbalance: If true, software IRQ balancing/affinity is disabled. */
+static int opt_noirqbalance = 0;
+boolean_param("noirqbalance", opt_noirqbalance);
 
 irq_desc_t irq_desc[NR_IRQS];
 
@@ -277,7 +282,7 @@
         desc->handler->startup(irq);
 
         /* Attempt to bind the interrupt target to the correct CPU. */
-        if ( desc->handler->set_affinity != NULL )
+        if ( !opt_noirqbalance && (desc->handler->set_affinity != NULL) )
             desc->handler->set_affinity(
                 irq, apicid_to_phys_cpu_present(d->processor));
     }
diff -r 7dc965fa6cce -r 0d3eaf70dedf docs/src/user.tex
--- a/docs/src/user.tex Thu Jul 14 08:50:01 2005
+++ b/docs/src/user.tex Thu Jul 14 10:34:57 2005
@@ -1101,7 +1101,7 @@
 To initialise a partition to support LVM volumes:
 \begin{quote}
 \begin{verbatim} 
-# pvcreate /dev/sda10          
+# pvcreate /dev/sda10           
 \end{verbatim} 
 \end{quote}
 
@@ -1705,6 +1705,11 @@
 \item [noht ] 
  Disable Hyperthreading. 
 
+\item [noirqbalance ] 
+ Disable software IRQ balancing and affinity. This can be used on
+ systems such as Dell 1850/2850 that have workarounds in hardware for
+ IRQ-routing issues.
+
 \item [badpage=$<$page number$>$,$<$page number$>$, \ldots ] 
  Specify a list of pages not to be allocated for use 
  because they contain bad bytes. For example, if your

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