Hi On Tue, Aug 3, 2021 at 12:55 AM Peter Maydell <peter.mayd...@linaro.org> wrote:
> On Mon, 2 Aug 2021 at 19:58, Marc-André Lureau > <marcandre.lur...@gmail.com> wrote: > > > > Hi Peter > > > > On Sun, Aug 1, 2021 at 4:10 PM Peter Maydell <peter.mayd...@linaro.org> > wrote: > >> > >> On Wed, 28 Jul 2021 at 16:47, Marc-André Lureau > >> <marcandre.lur...@gmail.com> wrote: > >> > I wish my previous pull request with the submodule change would > >> > receive more help or attention, as I either couldn't reproduce the > >> > failure (neither CI) or it was just some one-time warnings due to the > >> > transition... > >> > >> Well, I reported the failures back to you. I can't do a lot more, > >> because libslirp development is now much more opaque to me because > >> it doesn't happen in-tree. So instead of "some small change happens and > >> we pick up issues with it early", you have to deal with all of > >> the accumulated problems at once when you update the submodule :-( > >> > >> rc2 is on Tuesday, so we're starting to run short on time to > >> get an updated slirp in for 6.1. > >> > > > > Do you mind checking the https://github.com/elmarco/qemu/tree/libslirp > branch? > > > > From https://mail.gnu.org/archive/html/qemu-devel/2021-06/msg00031.html, > there would still be the one-time warnings from git, but osx and dist error > should be gone. > > Yep, I still see the git "warning: unable to rmdir 'slirp': Directory > not empty", but I think we can ignore that. > > I also see > config-host.mak is out-of-date, running configure > GIT ui/keycodemapdb meson tests/fp/berkeley-testfloat-3 > tests/fp/berkeley-softfloat-3 dtc capstone slirp > warn: ignoring non-existent submodule slirp > > but I think that is also a one-off? > yes > > Only one left as a mystery is the Ubuntu-ASAN link issue. > > This one is still here: > > subprojects/libslirp/libslirp.so.0.3.1.p/src_arp_table.c.o: In > function `arp_table_add': > > /mnt/nvmedisk/linaro/qemu-for-merges/build/clang/../../subprojects/libslirp/src/arp_table.c:51: > undefined reference to `__ubsan_handle_type_mismatch_v1' > > /mnt/nvmedisk/linaro/qemu-for-merges/build/clang/../../subprojects/libslirp/src/arp_table.c:51: > undefined reference to `__ubsan_handle_type_mismatch_v1' > > when building the subprojects/libslirp/libslirp.so.0.3.1 > > configure options: > '../../configure' '--cc=clang' '--cxx=clang++' '--enable-gtk' > '--extra-cflags=-fsanitize=undefined -fno-sanitize=shift-base > -Werror' > I am not able to reproduce. Could you check the value of default_library for libslirp when you run "meson configure". It should be "static". I tested with "make vm-build-ubuntu.amd64", with tests/vm/ubuntu.amd64: import sys import basevm import ubuntuvm DEFAULT_CONFIG = { 'install_cmds' : "apt-get update,"\ "apt-get build-dep -y qemu,"\ "apt-get install -y libfdt-dev language-pack-en ninja-build clang", } class UbuntuX64VM(ubuntuvm.UbuntuVM): name = "ubuntu.amd64" arch = "x86_64" image_link="https://cloud-images.ubuntu.com/releases/bionic/"\ "release-20191114/ubuntu-18.04-server-cloudimg-amd64.img" image_sha256="0c55fded766f3e4efb082f604ed71dd58c8e81f04bd1a66b4ced80ad62617547" BUILD_SCRIPT = """ set -e; cd $(mktemp -d); sudo chmod a+r /dev/vdb; tar -xf /dev/vdb; ./configure {configure_opts} --cc=clang --cxx=clang++ --host-cc=clang --extra-cflags='-fsanitize=undefined -fno-sanitize=shift-base -Werror' make --output-sync {target} -j{jobs} {verbose}; """ if __name__ == "__main__": sys.exit(basevm.main(UbuntuX64VM, DEFAULT_CONFIG)) > This happens because (as noted in the clang documentation for the > sanitizer: https://clang.llvm.org/docs/AddressSanitizer.html) > when linking a shared library with the sanitizers, clang does not > link in the sanitizer runtime library. That library is linked in > with the executable, and the shared library's references to the > sanitizer runtime functions are satisfied that way. However > you/meson are building libslirp.so with -Wl,--no-undefined > so the link of the .so fails. > (This does not happen with gcc, because gcc chose to make the > default for sanitizers to be to link against a shared libasan, > not a static one, the reverse of clang's default.) > > What I don't understand is why we're building the .so at all. > I just tried a fresh build with > '../../configure' '--cc=clang' '--cxx=clang++' '--enable-gtk' > '--enable-sanitizers' > to check that telling configure (and possibly thus meson) about > the sanitizers more directly still demonstrated the problem: > but that sidesteps it because it never builds the .so. > My other build directories (the ones that do plain old gcc > builds with no sanitizer) seem to have built the .so file > as well, though, so this isn't related to either clang or to > the sanitizers -- meson just doesn't seem to be consistent > about what we build. > > A related meson bug: > https://github.com/mesonbuild/meson/issues/764 > (which was closed by just making meson warn if you tell it > to both use --no-undefined (which is the default) and to use > the sanitizer.) > > The ideal fix seems to me to be to figure out why we're > building the libslirp .so and not do that. > > A simple fix/workaround would be to set "b_lundef = false" in > default_options in your meson.build (which will suppress the > -Wl,--no-undefined option). That does mean you won't get > any warnings if you accidentally make libslirp use a function > that is provided by the QEMU executable, I suppose. > > What if you pass --extra-ldflags='-fsanitize=undefined' then? thanks -- Marc-André Lureau
