My UltraSPARC U5 panics on boot about a memory alignment error when compiled with gcc4 and -O. Compiling with -O2 fixes this, and it should not adversly affect debugging. NOTE: This does not fix the memory alignment panic when loading kernel modules. Roy Marples (uberlord@gentoo.org) --- sys/conf/kern.pre.mk.old 2009-05-22 10:09:46 +0000 +++ sys/conf/kern.pre.mk 2009-05-22 10:10:27 +0000 @@ -22,15 +22,13 @@ COPTFLAGS?= -O .else . if defined(DEBUG) -_MINUS_O= -O CTFFLAGS+= -g . else -_MINUS_O= -O2 . endif . if ${MACHINE_ARCH} == "amd64" COPTFLAGS?=-O2 -frename-registers -pipe . else -COPTFLAGS?=${_MINUS_O} -pipe +COPTFLAGS?=-O2 -pipe . endif . if !empty(COPTFLAGS:M-O[23s]) && empty(COPTFLAGS:M-fno-strict-aliasing) COPTFLAGS+= -fno-strict-aliasing