Re: sysroot and coredump debugging

["Lluís Batlle i Rossell via Gdb" <gdb@sourceware.org>]

On Thu, Apr 24, 2025 at 03:01:56PM +0100, Luis Machado wrote:
> On 4/23/25 14:06, Lluís Batlle i Rossell via Gdb wrote:
> > I expect that I can run this in my development computer, after downloading
> > the core dump from the target system:
> > (gdb) set sysroot /mysysroot
> > (gdb) file myelf  #  it has debug info
> > (gdb) core-file core
> > 
> > And this never works; it drops the file with the symbols, thinking it's
> > unrelated to the core dump:
> > 
> > warning: Can't open file /home/user/myelf during file-backed mapping note
> > processing
> > warning: core file may not match specified executable file.
> 
> Unfortunately I think this is an area where improvements could be made. I know
> we have "substitute-path", but that's only for sources. In theory setting sysroot
> should work, but it doesn't seem to.
> 
> We want gdb to be strict about making sure the core file matches the ELF file, but
> we could have some adjustability here.

The "same absolute path" is never required when debugging core dumps
without sysroot, for dump/elf matching. Why does the sysroot introduce
that requirement? It looks like there is a small mistake somewhere, rather
than intended behavior.