I traced the problem to an entry I had placed in make.conf to correct deficiencies in some of the multimedia ports a few months ago (not correctly enabling MMX or SSE for amd64 builds). removing these entries eliminated build problems. -------- Original Message -------- Subject: problems building amd64 kernel, cvsup 3 hours ago, no apparent change since Date: Fri, 25 Jun 2010 17:43:11 -0700 From: bobf <bobf@mrp3.com> To: freebsd-stable@freebsd.org RELENG_8 - cvsup appx 15:00 PDT 1. performed 'make clean' followed by 'make buildworld'. Build complained that the architecture "amd64:i386" did not exist (I think that was the correct error message) on line 139 of Makefile.inc1 . 2. performed 'make buildworld TARGET=amd64' to force the build target. Everything appeared to work until the lib/libc target was reached, at which point an error on line 3 of syscall.S 'invalid register name %r10'. It appears that architecture selection is not working properly, and it prevents libc build from its compiling assembly language files. uname output FreeBSD hack.SFT.local 8.0-STABLE FreeBSD 8.0-STABLE #0: Wed Apr 7 11:02:24 PDT 2010 root@hack.SFT.local:/usr/obj/usr/src/sys/GENERIC amd64