[Xenomai] Won`t build on new Debian Stable
henning.schild at siemens.com
Thu Oct 19 18:55:57 CEST 2017
On Thu, 19 Oct 2017 12:03:33 +0200
Philippe Gerum <rpm at xenomai.org> wrote:
> On 10/13/2017 01:36 PM, Norbert Lange wrote:
> > I works, because collect2 (the "compiler driver", which documents
> > the -r option) now knows about the -r flag, using -Wl,-[U]r would
> > mean the flags aren't even looked at.
> > It can then disable functionality that is not supposed to be done at
> > this point (see gcc/collect2.c, search for 'early_exit'). It might
> > actually be in conflict with the -Ur option from the comments, but I
> > don't know what this is trying to solve (the constructor tables
> > would then be built in the second step?)
> > I would prefer the compiler driver knowing about the flags and
> > correctly dealing with them, instead of replicating this logic in
> > scripts (and keeping it up to date with this internal logic).
> > Might be that your wrapper script is doing something similarly by
> > filtering out the arguments for the first step, which might be the
> > same functionally that is skipped when adding '-r'
> > I dont know what the -Ur flag is trying to solve, and the first
> > patch adding -no-pie is way less likely to change something (given
> > that I would not have compiled with -pie before).
> > The new patch would however leave more of the magic to the toolchain
> > and seems more "correct" to me, for whatever that's worth. But it
> > might have some subtle differences to before, got some testcase
> > where lacking the -Ur flag made a difference?
> I don't know the original intent about passing -Ur to the linker,
> except maybe to stick to the ld manpage which states that the last
> partial link command should be given such option.
> However my understanding is that we don't need it in wrap-link.sh,
> since the script eventually completes the link stage to produce a
> fully resolved executable. That implies collecting the ctors/dtors and
> resolving all references from the partially linked object file anyway.
> Some testing only passing -r here seems to confirm this assumption
> with C++ apps; C++ users may want to check this too:
I just told some C++ power users to give that a try. I am not sure how
fast the feedback will arrive, i hope in the next two weeks.
> diff --git a/scripts/wrap-link.sh b/scripts/wrap-link.sh
> index aab7899..fa83bd5 100755
> --- a/scripts/wrap-link.sh
> +++ b/scripts/wrap-link.sh
> @@ -204,7 +204,7 @@ done
> if $stage2; then
> $verbose && set -x
> - $dryrun $cc -o "$output.tmp" -Wl,-Ur -nostdlib $stage1_args
> + $dryrun $cc -o "$output.tmp" -r -nostdlib $stage1_args
> $dryrun $cc -o "$output" "$output.tmp" $stage2_args
> $dryrun rm -f $output.tmp
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