On 01/21/19 20:30, Peter Maydell wrote: > On Mon, 21 Jan 2019 at 19:09, Laszlo Ersek <ler...@redhat.com> wrote: >> It wasn't clear to me whether and how multi-threaded builds were >> supposed to be used by maintainers, whenever they'd update >> "tests/data/uefi-boot-images/*". >> >> I saw that "make" was invoked everywhere as $(MAKE), but that didn't >> clarify any intent around "-j". So I didn't test "-j" at all, and in >> fact I wouldn't have expected it to work: > > The usual assumption with make is that "-jN" should work > and at least (if the thing being built can't actually > be parallelized usefully) be no worse than if you'd not > specified a -j option. We have occasionally had problems > with -jN in 'make check' (usually because several test cases > were trying to use the same temp filename or similar) but > we've treated them as bugs and squashed them. > >> The "build" base tool in edk2 implements part of the job with generated >> makefiles and invoking "make" itself, thus, despite .NOTPARALLEL, it >> likely inherits the outermost -j<N> setting -- and it doesn't expect such. >> >> So the best I can offer here is to check $MAKEFLAGS in "build.sh", and >> exit with an early, explicit error if $MAKEFLAGS contains "-j", "-l", or >> their long variants (--jobs, --load-average). > > Could you sanitize MAKEFLAGS in build.sh instead to remove the > parallelization options?
I've looked into MAKEFLAGS in a bit more depth now; both the documentation and some debug prints. Manipulating MAKEFLAGS looks somewhat brittle. So, I was about to suggest that I use the .NOTPARALLEL special target recommended by Phil, for the .efi binaries (which would ensure that no two instances of the "build" base tool run at the same time), *plus* that I submit a patch to edk2 so that the makefiles generated by the "build" tool also contain .NOTPARALLEL. (Because, to quote the make docs again, "If .NOTPARALLEL is mentioned as a target, then this invocation of make will be run serially, even if the ‘-j’ option is given. Any recursively invoked make command will still run recipes in parallel (unless its makefile also contains this target).") However: when I wanted to see the actual error from using .NOTPARALLEL *only* in "tests/uefi-test-tools/Makefile", and not in the build-generated makefiles, I failed to get any error. All the output images were built just fine. Phil: when you wrote that "The following patch didn't help" -- referring to .NOTPARALLEL, added only to "tests/uefi-test-tools/Makefile"-- , did you clean your tree first (with "make clean" or "git clean -ffdx")? Because now I'm thinking that the *individual* makefiles generated by edk2's "build" base tool might actually compatible with "-j", and your testing of .NOTPARALLEL failed only because your build tree (for example the Conf/ subdir -- list it with "-A") was in a messy state from your previous -j4 attempt (where you didn't use .NOTPARALLEL at all). Thanks Laszlo