OCaml + binutils 2.35 on i386

[Jerry James]

When ocamlopt is used with binutils 2.35 to link an executable, we now
get warnings that look like this:

/usr/bin/ld: tests/test_topsort.o: warning: relocation in read-only
section `.text'
/usr/bin/ld: warning: creating DT_TEXTREL in a PIE

There is an open upstream issue:

https://github.com/ocaml/ocaml/issues/9800

Here is an example of a build failure due to this:

https://koji.fedoraproject.org/koji/buildinfo?buildID=1576636

FYI.
-- 
Jerry James
http://www.jamezone.org/

[Richard W.M. Jones]

On Tue, Aug 04, 2020 at 01:48:45PM -0600, Jerry James wrote:
>  When ocamlopt is used with binutils 2.35 to link an executable, we
> now
>  get warnings that look like this:
>  
>  /usr/bin/ld: tests/test_topsort.o: warning: relocation in read-only
>  section `.text'
>  /usr/bin/ld: warning: creating DT_TEXTREL in a PIE 
32 bit is an architectural problem for OCaml.  Specifically because of
how the GC block headers are implemented it limits arrays / strings to
a maximum of 4M entries / 4M bytes, which was probably fine back in
the day but is unreasonably small today. [1]

So if something OCaml-related fails on i686, it's not something we
should worry about.  IMHO ExcludeArch %{ix86} and move on.

Rich.

[1] This is also the reason why multilib is completely irrelevant to OCaml
(and another reason why multilib should die).

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[Florian Weimer]

* Richard W. M. Jones:

>  On Tue, Aug 04, 2020 at 01:48:45PM -0600, Jerry James wrote:
> > When ocamlopt is used with binutils 2.35 to link an executable, we now
> > get warnings that look like this:
> > 
> > /usr/bin/ld: tests/test_topsort.o: warning: relocation in read-only
> > section `.text'
> > /usr/bin/ld: warning: creating DT_TEXTREL in a PIE
>
>  32 bit is an architectural problem for OCaml.  Specifically because of
>  how the GC block headers are implemented it limits arrays / strings to
>  a maximum of 4M entries / 4M bytes, which was probably fine back in
>  the day but is unreasonably small today. [1] 
I don't see how this is related to text relocations.

The problem seems to be lack of PIE support in ocamlopt on i386, as
correctly identified by the warning.

Thanks,
Florian

[Richard W.M. Jones]

On Wed, Aug 05, 2020 at 09:54:14AM +0200, Florian Weimer wrote:
>  * Richard W. M. Jones:
>  
>  > On Tue, Aug 04, 2020 at 01:48:45PM -0600, Jerry James wrote:
>  >> When ocamlopt is used with binutils 2.35 to link an executable, we now
>  >> get warnings that look like this:
>  >> 
>  >> /usr/bin/ld: tests/test_topsort.o: warning: relocation in read-only
>  >> section `.text'
>  >> /usr/bin/ld: warning: creating DT_TEXTREL in a PIE
>  >
>  > 32 bit is an architectural problem for OCaml.  Specifically because of
>  > how the GC block headers are implemented it limits arrays / strings to
>  > a maximum of 4M entries / 4M bytes, which was probably fine back in
>  > the day but is unreasonably small today. [1]
>  
>  I don't see how this is related to text relocations.
>  
>  The problem seems to be lack of PIE support in ocamlopt on i386, as
>  correctly identified by the warning. 
I mean any time spent fixing OCaml on 32 bit is time wasted.
If it happens on x86-64 then that's a problem we need to look at.

Rich.

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