apic: fix kvm build on UP without IOAPIC
authorMichael S. Tsirkin <mst@redhat.com>
Sun, 1 Jul 2012 15:05:06 +0000 (18:05 +0300)
committerMarcelo Tosatti <mtosatti@redhat.com>
Tue, 3 Jul 2012 17:55:29 +0000 (14:55 -0300)
commitf9808b7fd422b965cea52e05ba470e0a473c53d3
tree3e1657b6be4417851d3772aa7a71ba7f73ee1a3c
parentae7a2a3fb6f8b784c2752863f4f1f20c656f76fb
apic: fix kvm build on UP without IOAPIC

On UP i386, when APIC is disabled
# CONFIG_X86_UP_APIC is not set
# CONFIG_PCI_IOAPIC is not set

code looking at apicdrivers never has any effect but it
still gets compiled in. In particular, this causes
build failures with kvm, but it generally bloats the kernel
unnecessarily.

Fix by defining both __apicdrivers and __apicdrivers_end
to be NULL when CONFIG_X86_LOCAL_APIC is unset: I verified
that as the result any loop scanning __apicdrivers gets optimized out by
the compiler.

Warning: a .config with apic disabled doesn't seem to boot
for me (even without this patch). Still verifying why,
meanwhile this patch is compile-tested only.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reported-by: Randy Dunlap <rdunlap@xenotime.net>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
arch/x86/include/asm/apic.h