- Define NO_CPU_CFLAGS during BMAKE and TMAKE (and thus XMAKE) so that

bsd.cpu.mk doesn't have to worry about compilers other than the current
  version.
- Allow TARGET_CPUTYPE to override CPUTYPE in bsd.cpu.mk.
- Treat an empty CPUTYPE the same as an undefined CPUTYPE.
- For buildworld, buildkernel, etc., define TARGET_CPUTYPE to CPUTYPE for
  native builds and define it to be empty for cross-builds.
  TARGET_CPUTYPE is only defined if it is not already defined via the
  commandline or environment.

Makefile.inc1

@@ -126,8 +126,10 @@ MAKEOBJDIRPREFIX?=	/usr/obj
 TARGET_ARCH?=	${MACHINE_ARCH}
 .if ${TARGET_ARCH} == ${MACHINE_ARCH}
 TARGET?=	${MACHINE}
+TARGET_CPUTYPE?=	${CPUTYPE}
 .else
 TARGET?=	${TARGET_ARCH}
+TARGET_CPUTYPE?=
 .endif
 .if make(buildworld)
 BUILD_ARCH!=	sysctl -n hw.machine_arch
@@ -184,13 +186,14 @@ BMAKEENV=	MAKEOBJDIRPREFIX=${WORLDTMP} \
 		INSTALL="sh ${.CURDIR}/tools/install.sh"
 BMAKE=		${BMAKEENV} ${MAKE} -f Makefile.inc1 -DBOOTSTRAPPING \
 		-DNOHTML -DNOINFO -DNOMAN -DNOPIC -DNOPROFILE -DNOSHARED \
-		-DNO_WERROR
+		-DNO_CPU_CFLAGS -DNO_WERROR
 
 # build-tool stage
 TMAKEENV=	MAKEOBJDIRPREFIX=${OBJTREE} \
 		DESTDIR= \
 		INSTALL="sh ${.CURDIR}/tools/install.sh"
-TMAKE=		${TMAKEENV} ${MAKE} -f Makefile.inc1 -DBOOTSTRAPPING
+TMAKE=		${TMAKEENV} ${MAKE} -f Makefile.inc1 -DBOOTSTRAPPING \
+		-DNO_CPU_CFLAGS
 
 # cross-tool stage
 XMAKE=		TOOLS_PREFIX=${WORLDTMP} ${BMAKE} -DNO_FORTRAN -DNO_GDB

share/mk/bsd.cpu.mk

@@ -1,10 +1,16 @@
 # $FreeBSD$
 
+# Allow TARGET_CPUTYPE to override CPUTYPE to handle the cross-build case.
+
+.if defined(TARGET_CPUTYPE)
+CPUTYPE = ${TARGET_CPUTYPE}
+.endif
+
 # Set default CPU compile flags and baseline CPUTYPE for each arch.  The
 # compile flags must support the minimum CPU type for each architecture but
 # may tune support for more advanced processors.
 
-.if !defined(CPUTYPE)
+.if !defined(CPUTYPE) || ${CPUTYPE} == ""
 . if ${MACHINE_ARCH} == "i386"
 _CPUCFLAGS = -mcpu=pentiumpro
 CPUTYPE = i386
@@ -43,11 +49,7 @@ CPUTYPE = k7
 
 . if ${MACHINE_ARCH} == "i386"
 .  if ${CPUTYPE} == "k7"
-.   if defined(BOOTSTRAPPING)
-_CPUCFLAGS = -march=k6		# gcc 2.95.x didn't support athlon
-.   else
 _CPUCFLAGS = -march=athlon
-.   endif
 .  elif ${CPUTYPE} == "k6-2"
 _CPUCFLAGS = -march=k6
 .  elif ${CPUTYPE} == "k6"