[Bug compile/30295] New: Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[Bug compile/30295] New: Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[orbea at riseup dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

            Bug ID: 30295
           Summary: Undefined reference for gcore_elf_make_tdesc_note in
                    linux-tdep with slibtool
           Product: gdb
           Version: HEAD
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: compile
          Assignee: unassigned at sourceware dot org
          Reporter: orbea at riseup dot net
  Target Milestone: ---

Created attachment 14792
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14792&action=edit
Build fix patch

When building with slibtool there is an undefined reference for
'gcore_elf_make_tdesc_note' in linux-tdep.c. This can be solved by moving
gcore-elf.c to the same COMMON_SFILES variable as is gcore.c which is already
the same in the HFILES_NO_SRCDIR variable for the gcore-elf.h and gcore.h
header files.

I attached a patch showing a potential fix.

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[Bug compile/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[orbea at riseup dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

--- Comment #1 from orbea <orbea at riseup dot net> ---
Created attachment 14793
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14793&action=edit
Build log

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[Bug build/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|compile                     |build
                 CC|                            |tromey at sourceware dot org

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[Bug build/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

--- Comment #2 from Tom Tromey <tromey at sourceware dot org> ---
The problem here is that gcore-elf depends on ELF-specific code in BFD.
If that code is not compiled in, then gcore-elf.o would end up causing
a link failure (I think).

gdb/configure.ac has:

# Add ELF support to GDB, but only if BFD includes ELF support.
GDB_AC_CHECK_BFD([for ELF support in BFD], gdb_cv_var_elf,
                 [bfd_get_elf_phdr_upper_bound (NULL)], elf-bfd.h)
if test "$gdb_cv_var_elf" = yes; then
  CONFIG_OBS="$CONFIG_OBS elfread.o stap-probe.o dtrace-probe.o \
                gcore-elf.o elf-none-tdep.o"


So I think the question is why is that failing.
You could start by looking at the gdb config.log, but it may
just lead to the BFD config.log.

Also I suspect that fbsd-tdep.c and linux-tdep.c might need
some tweaks to check HAVE_ELF.  I see this in some other tdep files.

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[Bug build/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[orbea at riseup dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

--- Comment #3 from orbea <orbea at riseup dot net> ---
Created attachment 14794
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14794&action=edit
gdb/config.log

Okay I see the real problem in gdb/config.log.

configure:28213: checking for ELF support in BFD
configure:28233: ./libtool --quiet --mode=link x86_64-gentoo-linux-musl-gcc -o
conftest -I./../include -I../bfd -I./../bfd -O2 -pipe
-Werror=implicit-function-declaration -Werror=implicit-int      -L../bfd
-L../libiberty  -Wl,-O1 -Wl,--as-needed conftest.c -lbfd -liberty  -ltinfow
-lncursesw -lm  >&5
/usr/lib/gcc/x86_64-gentoo-linux-musl/12/../../../../x86_64-gentoo-linux-musl/bin/ld:
cannot find
/var/tmp/portage/sys-devel/gdb-9999/work/gdb-9999/bfd/.libs/libbfd.so: No such
file or directory
collect2: error: ld returned 1 exit status

It is using './libtool' when it should be using 'rlibtool' which is the
intended slibtool symlink. Mixing libtool implementations is not going to work.

Presumably this is from gdb/acinclude.m4 which sets:

CC="./libtool --quiet --mode=link $CC"

This problem seems to be repeated in libctf/configure.ac and
libctf/testsuite/lib/ctf-lib.exp. Is it required to use libtool as part of the
configure process here? Otherwise perhaps it can be set to the $LIBTOOL
variable?

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[Bug build/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[orbea at riseup dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

--- Comment #4 from orbea <orbea at riseup dot net> ---
Created attachment 14796
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14796&action=edit
Build fix patch (Attempt 2)

As a test I removed both of the overridden CC variables from gdb/configure:

CC="./libtool --quiet --mode=link $CC"

Which allows the configure test and build to succeed with both GNU libtool and
slibtool on my system. I am unsure if there is some edge case this would
expose?

I also tried removing it from gdb/acinclude.m4, but it is difficult to test
with autoconf-2.71 which Gentoo provides rather than autoconf-2.69 which GDB
seems to depend on. Regardless I attached a potential patch.

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[Bug build/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[orbea at riseup dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

--- Comment #5 from orbea <orbea at riseup dot net> ---
Created attachment 14844
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14844&action=edit
Build fix patch (Attempt 3)

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[Bug build/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

--- Comment #6 from Tom Tromey <tromey at sourceware dot org> ---
Hi.  Thanks for the patch.  gdb doesn't really deal
with patches in bugzilla; instead please see the
contribution checklist:

https://sourceware.org/gdb/wiki/ContributionChecklist

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[Bug build/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

--- Comment #7 from Tom Tromey <tromey at sourceware dot org> ---
*** Bug 31392 has been marked as a duplicate of this bug. ***

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[Bug build/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[orbea at riseup dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

--- Comment #8 from orbea <orbea at riseup dot net> ---
I am not sure the current patches are fully applicable anymore, as seen in the
duplicate issue with a more thorough description it needs some way to know the
bfd dependencies such as -lz which are listed in the .la file.

Additionally as suggested I sent the patches to the ML without much follow
through from the reviewer.

Any advice on how to best solve this?

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[Bug build/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

--- Comment #9 from Tom Tromey <tromey at sourceware dot org> ---
(In reply to orbea from comment #8)

> Additionally as suggested I sent the patches to the ML without much follow
> through from the reviewer.

Sorry about that.
Unfortunately for gdb you often have to "ping" patches.

> 
> Any advice on how to best solve this?

From what I can see, there's no real reason for GDB_AC_CHECK_BFD
to be doing a link check at all.
I wonder if changing this to do a compile check would help.

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[Bug build/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[orbea at riseup dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

--- Comment #10 from orbea <orbea at riseup dot net> ---
> From what I can see, there's no real reason for GDB_AC_CHECK_BFD
> to be doing a link check at all.
> I wonder if changing this to do a compile check would help.

This seems like a good idea, but when I tried it it results in undefined
references to 'bfd_mach_o_lookup_command' since both the ELF and MACH-O tests
now pass.

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[Bug build/30295] Undefined reference for gcore_elf_make_tdesc_note in linux-tdep with slibtool

[orbea at riseup dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=30295

--- Comment #11 from orbea <orbea at riseup dot net> ---
With the current slibtool git repo slibtoolize now exists and can be used
instead of GNU libtoolize. Additionally when using autoreconf it respects
LT_OUTPUT which allows the current gdb check to just work.

However using autoreconf for gdb is far from trivial and I was only able to
test it by hacking autoregen.py to have '-I /usr/share/slibtool' for the
appropriate autotools commands which would not be applicable for any system
that replaces libtool.m4 with a symlink to slibtool.m4.

Normally this can be achieved with:

export ACLOCAL='aclocal -I /usr/share/slibtool'
export LIBTOOLIZE='slibtoolize'

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