diff --git a/Makefile.inc1 b/Makefile.inc1
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -175,7 +175,24 @@
 .if ((defined(X_COMPILER_TYPE) && ${X_COMPILER_TYPE} == "gcc") || \
      (!defined(X_COMPILER_TYPE) && ${COMPILER_TYPE} == "gcc"))
 .if ${TARGET} == "arm"
-.error "armv6/armv7 build are broken with gcc. See https://reviews.freebsd.org/D36754"
+_GCC_BROKEN="https://reviews.freebsd.org/D36754"
+.endif
+.if ${TARGET_ARCH} == "powerpc"
+_GCC_BROKEN=Missing atomic builtins in libc++.
+.endif
+.if ${TARGET_ARCH:Mpowerpc64*}
+_GCC_BROKEN=libsys.so.7.full has a LOAD segment with RWX permissions.
+.endif
+.if ${TARGET} == "riscv"
+_GCC_BROKEN=boot code linker script issues.
+.endif
+.if defined(_GCC_BROKEN)
+.warning Target ${TARGET} is broken with GCC: ${_GCC_BROKEN}
+.if defined(TRY_GCC_BROKEN)
+.warning Trying build anyway.
+.else
+.error Avoiding broken build.  Define TRY_GCC_BROKEN to try anyway.
+.endif
 .endif
 .endif