From Newsgroup: muc.lists.freebsd.stable

This note is related to:

<https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=292567>

(__aeabi_unwind_cpp_pr1 has a similar status.)

It is not clear to me if other non-tier-1 architectures might have
something similar at issue, now or in the future.


Is the following expected? Appropriate?

In an armv7 context (watch for possible line wraps):

# readelf --dyn-syms /lib/libsys.so.7 | grep _cpp_
2: 00000000 0 NOTYPE GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr0
3: 00000000 0 NOTYPE GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr1

In more detail:

# readelf --dyn-syms /lib/libsys.so.7

Symbol table '.dynsym' contains 1211 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 00000000 0 NOTYPE WEAK DEFAULT UND __cxa_finalize
2: 00000000 0 NOTYPE GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr0
3: 00000000 0 NOTYPE GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr1
. . .

on aarch64:

# readelf --dyn-syms /lib/libsys.so.7 | grep _cpp_
#

on amd64:

# readelf --dyn-syms /lib/libsys.so.7 | grep _cpp_
#

For armv7 at least, it contributes to the likes of (not specific to
gcc15 for similar results):

# gcc15 -static-libgcc main.c

producing messages like:

/usr/local/bin/ld: a.out: hidden symbol `__aeabi_unwind_cpp_pr0' in /usr/local/lib/gcc15/gcc/armv7-portbld-freebsd16.0/15.2.0/libgcc_eh.a(unwind-arm.o)
is referenced by DSO
/usr/local/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status

In fact:

# gcc15 -static-libgcc -fno-exceptions main.c

also produces:

/usr/local/bin/ld: a.out: hidden symbol `__aeabi_unwind_cpp_pr0' in /usr/local/lib/gcc15/gcc/armv7-portbld-freebsd16.0/15.2.0/libgcc_eh.a(unwind-arm.o)
is referenced by DSO
/usr/local/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status

Despite the very simple C context.

In an armv7 14.3-STABLE context (so predating a
libsys.so.7 existing to be involved with libc.so.7 use):

# llvm-readelf --dyn-syms /lib/libc.so.7 | grep _cpp_
#

So in 14.* there is no such __aeabi_unwind_cpp_pr0 reference involved
when linking against libc.so.7 . (Same for __aeabi_unwind_cpp_pr1 .)

Definitely only a FreeBSD 15+ issue for what contexts can run into the
issue.


A question here is if, at least for armv7, all use of -static-libgcc for FreeBSD 15+ needs to supply a usable/linkable pair:

__aeabi_unwind_cpp_pr0
__aeabi_unwind_cpp_pr1

even if -fno-exceptions is also in use.
--
===
Mark Millard
marklmi at yahoo.com



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From Newsgroup: muc.lists.freebsd.stable

On 1/19/26 13:37, Mark Millard wrote:

This note is related to:

<https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=292567>

(__aeabi_unwind_cpp_pr1 has a similar status.)

It is not clear to me if other non-tier-1 architectures might have
something similar at issue, now or in the future.

Is the following expected? Appropriate?

In an armv7 context (watch for possible line wraps):

# readelf --dyn-syms /lib/libsys.so.7 | grep _cpp_
2: 00000000 0 NOTYPE GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr0
3: 00000000 0 NOTYPE GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr1

In more detail:

# readelf --dyn-syms /lib/libsys.so.7

Symbol table '.dynsym' contains 1211 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 00000000 0 NOTYPE WEAK DEFAULT UND __cxa_finalize
2: 00000000 0 NOTYPE GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr0
3: 00000000 0 NOTYPE GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr1
. . .

on aarch64:

# readelf --dyn-syms /lib/libsys.so.7 | grep _cpp_
#

on amd64:

# readelf --dyn-syms /lib/libsys.so.7 | grep _cpp_
#

For armv7 at least, it contributes to the likes of (not specific to
gcc15 for similar results):

# gcc15 -static-libgcc main.c

producing messages like:

/usr/local/bin/ld: a.out: hidden symbol `__aeabi_unwind_cpp_pr0' in /usr/local/lib/gcc15/gcc/armv7-portbld-freebsd16.0/15.2.0/libgcc_eh.a(unwind-arm.o)
is referenced by DSO
/usr/local/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status

In fact:

# gcc15 -static-libgcc -fno-exceptions main.c

also produces:

/usr/local/bin/ld: a.out: hidden symbol `__aeabi_unwind_cpp_pr0' in /usr/local/lib/gcc15/gcc/armv7-portbld-freebsd16.0/15.2.0/libgcc_eh.a(unwind-arm.o)
is referenced by DSO
/usr/local/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status

Despite the very simple C context.

In an armv7 14.3-STABLE context (so predating a
libsys.so.7 existing to be involved with libc.so.7 use):

# llvm-readelf --dyn-syms /lib/libc.so.7 | grep _cpp_
#

So in 14.* there is no such __aeabi_unwind_cpp_pr0 reference involved
when linking against libc.so.7 . (Same for __aeabi_unwind_cpp_pr1 .)

Definitely only a FreeBSD 15+ issue for what contexts can run into the
issue.

A question here is if, at least for armv7, all use of -static-libgcc for FreeBSD 15+ needs to supply a usable/linkable pair:

__aeabi_unwind_cpp_pr0
__aeabi_unwind_cpp_pr1

even if -fno-exceptions is also in use.

The examples of the aarch64 and amd64 grep usage that I copy/pasted into
my notes were poor, assuming naming conventions that need not be
assumed. Better was my test via (watch for potential line wrapping):

aarch64 main:

# readelf --dyn-syms /lib/libsys.so.7 | grep 'NOTYPE GLOBAL DEFAULT UN'
# readelf --dyn-syms /lib/libc.so.7 | grep 'NOTYPE GLOBAL DEFAULT UN'
1: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND environ
2: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND __progname


amd64 main:

# readelf --dyn-syms /lib/libsys.so.7 | grep 'NOTYPE GLOBAL DEFAULT UN'
# readelf --dyn-syms /lib/libc.so.7 | grep 'NOTYPE GLOBAL DEFAULT UN'
1: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND environ
2: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND __progname


Compared/contrasted with:

armv7 main:

# readelf --dyn-syms /lib/libsys.so.7 | grep 'NOTYPE GLOBAL DEFAULT UN'
2: 00000000 0 NOTYPE GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr0
3: 00000000 0 NOTYPE GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr1
# readelf --dyn-syms /lib/libc.so.7 | grep 'NOTYPE GLOBAL DEFAULT UN'
1: 00000000 0 NOTYPE GLOBAL DEFAULT UND environ
2: 00000000 0 NOTYPE GLOBAL DEFAULT UND __progname

And with:

armv7 14.3-STABLE:

# llvm-readelf --dyn-syms /lib/libc.so.7 | grep 'NOTYPE GLOBAL DEFAULT
UN'
2: 00000000 0 NOTYPE GLOBAL DEFAULT UND environ
3: 00000000 0 NOTYPE GLOBAL DEFAULT UND __progname
--
===
Mark Millard
marklmi at yahoo.com


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