From 59d21e537b6c3a964d4e346e9cf2a1e17267a27c Mon Sep 17 00:00:00 2001 From: Alexander Graf Date: Sun, 17 Jul 2011 07:30:29 +0200 Subject: [PATCH] xen: make xen_enabled even more clever When using xen_enabled() we're currently only checking if xen is enabled at all during the build. But what if you want to build multiple targets out of which only one can potentially run xen code? That means that for generic code we'll still have to fall back to the variable and potentially slow the code down, but it's not as important as that is mostly xen device emulation which is not touched for non-xen targets. The target specific code however can with this patch see that it's unable to ever execute xen code. We can thus always return 0 on xen_enabled(), giving gcc enough hints to evict the mapcache code from the target memory management code. Signed-off-by: Alexander Graf Acked-by: Anthony PERARD --- configure | 5 +++++ hw/xen.h | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/configure b/configure index cd399dc..bc3495c 100755 --- a/configure +++ b/configure @@ -3290,7 +3290,12 @@ case "$target_arch2" in if test "$xen" = "yes" -a "$target_softmmu" = "yes" ; then target_phys_bits=64 echo "CONFIG_XEN=y" >> $config_target_mak + else + echo "CONFIG_NO_XEN=y" >> $config_target_mak fi + ;; + *) + echo "CONFIG_NO_XEN=y" >> $config_target_mak esac case "$target_arch2" in i386|x86_64|ppcemb|ppc|ppc64|s390x) diff --git a/hw/xen.h b/hw/xen.h index 43b95d6..2162111 100644 --- a/hw/xen.h +++ b/hw/xen.h @@ -24,7 +24,7 @@ extern int xen_allowed; static inline int xen_enabled(void) { -#ifdef CONFIG_XEN_BACKEND +#if defined(CONFIG_XEN_BACKEND) && !defined(CONFIG_NO_XEN) return xen_allowed; #else return 0; -- 2.7.4