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authorAshok Raj <ashok.raj@intel.com>2005-06-25 14:54:52 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-25 16:24:29 -0700
commit67664c8f7e74def5adf66298a1245d82af72db2c (patch)
treec98657d833d3ca61322a8ae54023814ebc36a480 /arch/i386
parentf370513640492641b4046bfd9a6e4714f6ae530d (diff)
[PATCH] i386: Dont use IPI broadcast when using cpu hotplug.
This patch introduces a startup parameter no_broadcast. When we enable CONFIG_HOTPLUG_CPU, we dont want to use broadcast shortcut as it has ill effects on a offline cpu. If we issue broadcast, the IPI is also delivered to offline cpus, or partially up cpu causing stale IPI's to be handled, which is a problem and can cause undesirable effects. Introduces a new startup cmdline option no_ipi_broadcast, that can be switched at cmdline if necessary. Signed-off-by: Ashok Raj <ashok.raj@intel.com> Acked-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/i386')
-rw-r--r--arch/i386/mach-default/setup.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/arch/i386/mach-default/setup.c b/arch/i386/mach-default/setup.c
index 0aa08eaa893..e5a1a83d09e 100644
--- a/arch/i386/mach-default/setup.c
+++ b/arch/i386/mach-default/setup.c
@@ -10,6 +10,14 @@
#include <asm/acpi.h>
#include <asm/arch_hooks.h>
+#ifdef CONFIG_HOTPLUG_CPU
+#define DEFAULT_SEND_IPI (1)
+#else
+#define DEFAULT_SEND_IPI (0)
+#endif
+
+int no_broadcast=DEFAULT_SEND_IPI;
+
/**
* pre_intr_init_hook - initialisation prior to setting up interrupt vectors
*
@@ -104,3 +112,22 @@ void __init mca_nmi_hook(void)
printk("NMI generated from unknown source!\n");
}
#endif
+
+static __init int no_ipi_broadcast(char *str)
+{
+ get_option(&str, &no_broadcast);
+ printk ("Using %s mode\n", no_broadcast ? "No IPI Broadcast" :
+ "IPI Broadcast");
+ return 1;
+}
+
+__setup("no_ipi_broadcast", no_ipi_broadcast);
+
+static int __init print_ipi_mode(void)
+{
+ printk ("Using IPI %s mode\n", no_broadcast ? "No-Shortcut" :
+ "Shortcut");
+ return 0;
+}
+
+late_initcall(print_ipi_mode);