gdb reports Single stepping until exit from function _start, which has no line number information.

[Patrick Clot via Gdb <gdb@sourceware.org>]

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Attached is a debug file that has the version numbers
of the software I am using and the gdb session.

Thanks in advance,
Patrick Clot

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---------------------------------------------
Version of NASM: NASM version 2.15.05
---------------------------------------------

---------------------------------------------
Version of ld:

GNU ld (GNU Binutils for Ubuntu) 2.38
Copyright (C) 2022 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) a later version.
This program has absolutely no warranty.
---------------------------------------------

---------------------------------------------
Version of gdb:

GNU gdb (Ubuntu 12.1-0ubuntu1~22.04.2) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
---------------------------------------------

-------------- how to build -----------------
$ nasm -f elf64 -g -F dwarf -l forth.lst -o forth.o forth.asm
$ ld -o forth forth.o
---------------------------------------------

----------- gdb forth session ---------------
Reading symbols from forth...
(gdb) b _start
Breakpoint 1 at 0x401004
(gdb) run
Starting program: /home/pmc/tmp/forth

Breakpoint 1, 0x0000000000401004 in _start ()
(gdb) n
Single stepping until exit from function _start,
which has no line number information.
0x0000000000401020 in _start.outer_loop ()
(gdb)
----------- end gdb forth session ---------------