@@ -1,4 +1,4 @@
-# $NetBSD: Makefile,v 1.175 2020/06/13 13:15:44 gdt Exp $
+# $NetBSD: Makefile,v 1.176 2020/06/13 14:18:41 gdt Exp $
 
 DISTNAME=	rustc-1.43.1-src
 PKGNAME=	${DISTNAME:S/rustc/rust/:S/-src//}
@@ -137,14 +137,23 @@
 .endif
 
 .if ${OPSYS} == "NetBSD"
-# On older versions of NetBSD, parallel builds cause problems.
+# Parallel builds failed on NetBSD due to dynamic linker locking bugs.
 # \todo Explain if the build is believed to be sound if not parallel,
 # or if a non-parallel build is merely more likely to work.
+#
 # See toolchain/54192 at
-# http://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=54192
-# \todo Explain if this has been pulled up to 8 and 9, and 
+#   http://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=54192
+# which was fixed in -current on 2020-04-19:
+#   http://mail-index.netbsd.org/source-changes/2020/04/16/msg116256.html
+#   http://mail-index.netbsd.org/source-changes/2020/04/19/msg116337.html
+# These  were pulled up to netbsd-9 on 2020-05-13:
+#   http://releng.netbsd.org/cgi-bin/req-9.cgi?show=907
+# This has not been pulled up to netbsd-8
+#   \todo Explain if it's not applicable, shouldn't be pulled up, should be
+#   but hasn't, is too hard, etc.
 
 # If we aren't on 9-current, and are on 8.x or 9.x, avoid parallel.
+# \todo Consider avoiding setting this on netbsd-9 past the fix.
 .if empty(MACHINE_PLATFORM:MNetBSD-9.99.*) && !empty(MACHINE_PLATFORM:MNetBSD-[1-9].*)
 MAKE_JOBS_SAFE=	no
 .endif