[Buildroot] [PATCH v2, 1/1] brltty: use gcc instead of ld to link shared objects

[Fabrice Fontaine]

Dear Mario, Thomas,

Le ven. 21 sept. 2018 à 08:34, Mario Lang <mlang at blind.guru> a écrit :

> Fabrice Fontaine <fontaine.fabrice at gmail.com> writes:
>
> > Dear Thomas,
> >
> > Le jeu. 20 sept. 2018 à 21:01, Thomas Petazzoni <
> > thomas.petazzoni at bootlin.com> a écrit :
> >
> >> Hello,
> >>
> >> On Thu, 20 Sep 2018 19:28:09 +0200, Fabrice Fontaine wrote:
> >> > Bump to version 5.6 has reintroduced the issue fixed by patch 854093
> on
> >> > version 5.5.
> >> >
> >> > Indeed, third patch was merged upstream but it was then reverted:
> >> >
> >>
> https://github.com/brltty/brltty/commit/9e7d62c869d3c1cbe12dda8b0291a4692c193416
> >> >
> >> > Moreover, since commit 3a2e3f6fa5ef0a210ffeba5ed05c79965d0cc3c7, MKOBJ
> >> > was renamed into MKREL. So, instead of patching again brltty,
> overwrite
> >> > MKREL to use "gcc -shared -o" instead of "ld -r -o".
> >>
> >> Are you really sure gcc -shared -o does the same thing as ld -r -o ?
>
> ld fails to link on mipsel at least.  What else should we do?
> "ABI is incompatible with that of the selected emulation"
> "Attempt to do relocatable link with elf64-tradlittlemips input and
> elf32-ntradlittlemips output"
>
After more investigations, it seems that this issue is raised only on
mips64el (at least on autobuilders:
http://autobuild.buildroot.org/?reason=brltty-5.6).
On this target, by default, ld wants to link a 32 bits binary (I don't know
why).
This issue can be fixed by setting LD="$(TARGET_LD) -melf64ltsmip".
However, I don't know if this a better solution, it seems like a workaround
to a toolchain issue.

>
> Hmm, maybe this is a HOST/TARGET mixup?  But how?
>
> > I didn't think about it, I basically backported the behavior of third
> patch
> > (upstream commit 4c8aba42e246b96d10ffcbd57653682375499e46). The third
> patch
> > applied to brltty 5.5 (https://patchwork.ozlabs.org/patch/854093/) was
> > replacing MKOBJ ($(LD) -r -o) by MKMOD defined as (CC)
> > ${brltty_mkmod_gcc_make=-shared}
> > BRLTTY_OPTIONS_LD2CC([${brltty_mkmod_ld_options}]) -o" with
> > brltty_mkmod_ld_make="-shared" on linux (see
> >
> https://github.com/brltty/brltty/blob/4c8aba42e246b96d10ffcbd57653682375499e46/configure.ac
> > ).
> > More information can be found here:
> > https://github.com/brltty/brltty/pull/113
> > However, I don't know why this commit was reverted one week later.
> > Mario, you told us in the review of the first patch that the upstream
> > author decided to "fix" the issue in a different way but actually the
> issue
> > is not fixed. Do you know why this commit was reverted? If needed, I can
> > create an issue to get more info.
>
> It was reverted because it failed to build on Mac OS X, and Mac OS X was
> deemed more important then cross-compiling on Linux.
>
> Upstream (dave at mielke.cc) is very responsive, maybe you have more luck
> trying to work this one out with him?
>
> --
> CYa,
>   ⡍⠁⠗⠊⠕
>
Best Regards,

Fabrice
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