From dean-list-linux-kernel@arctic.org Thu Jan 29 00:46:53 2004 Date: Thu, 6 Jun 2002 11:31:48 -0700 (PDT) From: dean gaudet To: Keith Owens Cc: linux-kernel@vger.kernel.org, Alan Cox Subject: Re: Linux 2.4.19-pre10-ac2 X-comment: visit http://arctic.org/~dean/legal for information regarding copyright and disclaimer. On Thu, 6 Jun 2002, Keith Owens wrote: > On Thu, 6 Jun 2002 11:11:09 +0100 (BST), > Matt Bernstein wrote: > >Since when was it OK to do a parallel make dep? > > Arch dependent. Parallel make dep will generate incomplete output on > some architectures, mainly those that generate files at make dep time. > mkdep.c only adds .h files to .[h]depend if the file exists. With > parallel make dep the scanning of .c files can occur before the .h > files have been generated, resulting in an incomplete dependency tree. > Later changes may not rebuild everything that should be rebuilt. hmm, so i can imagine there being a race condition there somewhere... but i just tried comparing a few "make -j3 dep" trees versus a "make dep" tree and there weren't any differences. (i'm building for i386). anyhow, i think i see the problem. in the top level Makefile there's this: tmp_include_depends: include/config/MARKER dummy $(MAKE) -r -f tmp_include_depends all and if you look in tmp_include_depends it has all the header files on the LHS of dependencies (it touches them all)... but there's no .PRECIOUS for any of the header files. so if you hit ^C while this is going on you'll lose source files. i believe the patch below fixes the problem... but i couldn't hit ^C at the right time to reproduce it, so maybe there's something else going on. btw, it doesn't appear like anything actually uses .hdepend... at least i couldn't see a use when i grepped the tree for '\.hdepend', maybe it's hidden somewhere. -dean --- linux/Makefile.orig Thu Jun 6 10:44:29 2002 +++ linux/Makefile Thu Jun 6 11:26:36 2002 @@ -494,6 +494,7 @@ endif (find $(TOPDIR) \( -name .depend -o -name .hdepend \) -print | xargs $(AWK) -f scripts/include_deps) > tmp_include_depends sed -ne 's/^\([^ ].*\):.*/ \1 \\/p' tmp_include_depends > tmp_include_depends_1 + (echo ""; echo ".PRECIOUS: \\"; cat tmp_include_depends_1; echo "") >> tmp_include_depends (echo ""; echo "all: \\"; cat tmp_include_depends_1; echo "") >> tmp_include_depends rm tmp_include_depends_1