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(); _