[PATCH 41/91] xen/smp: Warn user why they keel over - nosmp or noapic and what to use instead.

From: Willy Tarreau
Date: Sun Feb 05 2012 - 17:41:42 EST


2.6.27-longterm review patch. If anyone has any objections, please let us know.

------------------

commit ed467e69f16e6b480e2face7bc5963834d025f91 upstream.

We have hit a couple of customer bugs where they would like to
use those parameters to run an UP kernel - but both of those
options turn of important sources of interrupt information so
we end up not being able to boot. The correct way is to
pass in 'dom0_max_vcpus=1' on the Xen hypervisor line and
the kernel will patch itself to be a UP kernel.

Fixes bug: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=637308

Acked-by: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
arch/x86/xen/smp.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)

Index: longterm-2.6.27/arch/x86/xen/smp.c
===================================================================
--- longterm-2.6.27.orig/arch/x86/xen/smp.c 2012-02-05 22:34:33.783914838 +0100
+++ longterm-2.6.27/arch/x86/xen/smp.c 2012-02-05 22:34:40.668915455 +0100
@@ -33,6 +33,7 @@
#include <xen/page.h>
#include <xen/events.h>

+#include <xen/hvc-console.h>
#include "xen-ops.h"
#include "mmu.h"

@@ -182,6 +183,15 @@
{
unsigned cpu;

+ if (skip_ioapic_setup) {
+ char *m = (max_cpus == 0) ?
+ "The nosmp parameter is incompatible with Xen; " \
+ "use Xen dom0_max_vcpus=1 parameter" :
+ "The noapic parameter is incompatible with Xen";
+
+ xen_raw_printk(m);
+ panic(m);
+ }
xen_init_lock_cpu(0);

smp_store_cpu_info(0);


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