Commit 621a0147d5c921f4cc33636ccd0602ad5d7cbfbc ("ARM: 7757/1: mm: don't flush icache in switch_mm with hardware broadcasting") breaks the boot on OMAP2430SDP with omap2plus_defconfig. Tracked to an undefined instruction abort from the CP15 read in cache_ops_need_broadcast(). It turns out that gcc 4.5 reorders the extended CP15 read above the is_smp() test. This breaks ARM1136 r0 cores, since they don't support several CP15 registers that later ARM cores do. ARM1136JF-S TRM section 3.2.1 "Register allocation" has the details. So mark the extended CP15 read as clobbering memory, which prevents the compiler from reordering it before the is_smp() test. Russell states that the code generated from this approach is preferable to marking the inline asm as volatile. Remove the existing condition code clobber as it's obsolete, per Nico's post: http://www.spinics.net/lists/arm-kernel/msg261208.html This patch is a collaboration with Will Deacon and Russell King. Comments from Paul Walmsley: Russell, if you accept this one, might you also add Will's ack from the lists: Comments from Paul Walmsley: I'd also be obliged if you could add a Cc: line for Jonathan Austin, since he helped test: Signed-off-by: Paul Walmsley <paul@pwsan.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: Tony Lindgren <tony@atomide.com> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Jonathan Austin <jonathan.austin@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>