[Bug driver/111084] New: Support configurable dynamic linker path

[Bug driver/111084] New: Support configurable dynamic linker path

[hdante at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111084

            Bug ID: 111084
           Summary: Support configurable dynamic linker path
           Product: gcc
           Version: 13.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: driver
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hdante at gmail dot com
  Target Milestone: ---

Hello, it's not possible, currently, to set the dynamic linker root path when
building gcc. The current workaround is to modify the source code and/or spec
file, as shown, for example, by the "linux from scratch" scripts, when
compiling a toolchain rooted at /tools:

    ## Change the location of GCC's default dynamic linker to use the one
installed in /tools
    #
    # For i686/x86_64:
    for file in gcc/config/{linux,i386/linux{,64}}.h
    do
      cp -uv $file{,.orig}
      sed -e 's/\/lib\(64\)\?\(32\)\?\/ld/\/tools&/g' \
          -e 's/\/usr/\/tools/g' ${file}.orig > ${file}
      echo '
    #undef STANDARD_STARTFILE_PREFIX_1
    #undef STANDARD_STARTFILE_PREFIX_2
    #define STANDARD_STARTFILE_PREFIX_1 "/tools/lib/"
    #define STANDARD_STARTFILE_PREFIX_2 ""' >> ${file}
      touch ${file}.orig
    done

(...)

    case $(uname -m) in
       i686)   # for i386
               sed -i
's/\/lib\/ld-musl-i386.so.1/\/tools\/lib\/ld-musl-i386.so.1/g' tempspecfile
               # check with sed
               grep "/tools/lib/ld-musl-i386.so.1" tempspecfile  --color=auto
               ;;

(etc.)

Can you add a configuration parameter to support changing the dynamic linker
root path ?

Thanks,

[Bug driver/111084] Support configurable dynamic linker path

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111084

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2023-08-20

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Why do you want to modify the location of the dynamic loader since it is fixed
by the ABI?

If you have a different ABI, you should just have a new config target instead
or use sysroots/chroots to run the new programs.

The way Linux from scratch is handling this is most likely just broken.

[Bug driver/111084] Support configurable dynamic linker path

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111084

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 52556 anyways.

*** This bug has been marked as a duplicate of bug 52556 ***

[Bug driver/111084] Support configurable dynamic linker path

[hdante at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111084

--- Comment #3 from Henrique <hdante at gmail dot com> ---
Hello, the reason is that linux from scratch bootstraps an initial toolchain
decoupled from the host toolchain before installing the final system. The final
installation will use the correct paths. The initial toolchain, however, uses a
separate directory. The procedure is not broken, it's actually pretty clean and
not specific to linux from scratch, other toolchain builders will do the same
thing (IIRC buildroot).

Is it possible to have a configure flag for changing the dynamic linker root ?

Thanks,

[Bug driver/111084] Support configurable dynamic linker path

[xry111 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111084

Xi Ruoyao <xry111 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |xry111 at gcc dot gnu.org

--- Comment #4 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
(In reply to Henrique from comment #3)
> Hello, the reason is that linux from scratch bootstraps an initial toolchain
> decoupled from the host toolchain before installing the final system. The
> final installation will use the correct paths. The initial toolchain,
> however, uses a separate directory. The procedure is not broken, it's
> actually pretty clean and not specific to linux from scratch, other
> toolchain builders will do the same thing (IIRC buildroot).

It's not clean and it had caused a lot of troubles.  Linux From Scratch has
switched away from this approach years ago.

If you must stay with this bad approach then fine, but do not refer it as Linux
From Scratch because doing so will mislead people.

[Bug driver/111084] Support configurable dynamic linker path

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111084

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Also buildroot uses sysroots and chroot/containers instead.

Containers/chroot is the better approach anyways.

[Bug driver/111084] Support configurable dynamic linker path

[xry111 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111084

--- Comment #6 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #5)
> Also buildroot uses sysroots and chroot/containers instead.
> 
> Containers/chroot is the better approach anyways.

We use sysroot and chroot since Linux From Scratch 10.0 (released Sept 2020).