From: Kei Tokunaga <ktokunag@redhat.com>
Subject: [RHEL5.1 PATCH 16/21] Skip MCA setup on domU
Date: Thu, 07 Jun 2007 03:45:30 -0400
Bugzilla: 242143
Message-Id: <4667B79A.1060404@redhat.com>
Changelog: [xen] ia64: Skip MCA setup on domU


bz242143
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=242143

Backport of cset#14805.

This effectively automates passing the nomca flag to
domUs, preventing them from setting up CMC/CPE interrupts.
This saves 3 dynamic IRQs per processor and allows us
to get domUs up to 64 vCPUs without increasing the number
of dynamic IRQs available.

Thanks,
Kei


rh bug 242143

# HG changeset patch
# User Alex Williamson <alex.williamson@hp.com>
# Date 1176298109 21600
# Node ID a6800d989059304f7b4b0e55eec297b5af8bce15
# Parent  7158623a1b3dd28f86f908fce7e8e56c37a49179
[IA64] Skip MCA setup on domU

This effectively automates passing the nomca flag to domUs,
preventing them from setting up CMC/CPE interrupts.  This saves
3 dynamic IRQs per processor and allows us to get domUs up to 64
vCPUs without increasing the number of dynamic IRQs available.

Signed-off-by: Alex Williamson <alex.williamson@hp.com>


---

 linux-2.6.18-21.el5-gerd-order-kei/arch/ia64/kernel/setup.c |    4 ++++
 1 file changed, 4 insertions(+)

diff -puN arch/ia64/kernel/setup.c~14805-IA64_Skip_MCA_setup_on_domU arch/ia64/kernel/setup.c
--- linux-2.6.18-21.el5-gerd-order/arch/ia64/kernel/setup.c~14805-IA64_Skip_MCA_setup_on_domU	2007-06-07 02:44:33.000000000 -0400
+++ linux-2.6.18-21.el5-gerd-order-kei/arch/ia64/kernel/setup.c	2007-06-07 02:44:33.000000000 -0400
@@ -656,6 +656,10 @@ setup_arch (char **cmdline_p)
 #endif
 
 	/* enable IA-64 Machine Check Abort Handling unless disabled */
+#ifdef CONFIG_XEN
+	if (is_running_on_xen() && !is_initial_xendomain())
+		nomca = 1;
+#endif
 	if (!nomca)
 		ia64_mca_init();
 

_