Re: gdb failure: "core file format not supported"

Hi Finn,

On Mon, Mar 27, 2023 at 2:47 AM Finn Thain <[email protected]> wrote:
> I wasn't able to add the linux-m68k list to the bug report Cc list.
>
> I'm forwarding this as I don't know the answer to Tom's question...
>
> On Sat, 25 Mar 2023, tromey at sourceware dot org wrote:
>
> > https://sourceware.org/bugzilla/show_bug.cgi?id=30273
> >
> > Tom Tromey <tromey at sourceware dot org> changed:
> >
> >            What    |Removed                     |Added
> > ----------------------------------------------------------------------------
> >                  CC|                            |tromey at sourceware dot org
> >
> > --- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
> > This is probably a regression due to this patch:
> >
> > commit 3eba3a011a89c75c10bd1860eee4589e65697165
> > Author: Tom Tromey <[email protected]>
> > Date:   Mon Sep 14 08:30:10 2020 -0600
> >
> >     Various m68k fixes for gdb
> >
> >
> > When I debug gdb I see it decides this core file is
> > GDB_OSABI_SVR4, not GDB_OSABI_LINUX.  This happens
> > because m68k_osabi_sniffer takes this branch:
> >
> >   if (elfosabi == ELFOSABI_NONE)
> >     return GDB_OSABI_SVR4;
> >
> > From elf/common.h:
> >
> > #define ELFOSABI_NONE         0 /* UNIX System V ABI */
> > #define ELFOSABI_HPUX         1 /* HP-UX operating system */
> > #define ELFOSABI_NETBSD       2 /* NetBSD */
> > #define ELFOSABI_GNU          3 /* GNU */
> > #define ELFOSABI_LINUX        3 /* Alias for ELFOSABI_GNU */
> >
> >
> > So I guess one question is why this core file isn't marked
> > as ELFOSABI_LINUX.

Only PA-RISC and the remoteproc core dumper seem to use
ELFOSABI_LINUX?

    arch/parisc/include/asm/elf.h:#define ELF_OSABI         ELFOSABI_LINUX
    arch/parisc/kernel/ptrace.c:    .name = "parisc", .e_machine =
ELF_ARCH, .ei_osabi = ELFOSABI_LINUX,
    arch/parisc/kernel/ptrace.c:    .name = "parisc", .e_machine =
EM_PARISC, .ei_osabi = ELFOSABI_LINUX,

    include/uapi/linux/elf.h:#ifndef ELF_OSABI
    include/uapi/linux/elf.h:#define ELF_OSABI ELFOSABI_NONE
    include/uapi/linux/elf.h-#endif

    fs/proc/kcore.c:                                [EI_OSABI] = ELF_OSABI,

    drivers/remoteproc/remoteproc_elf_helpers.h:
hdr->e_ident[EI_OSABI] = ELFOSABI_NONE;

Or perhaps it's set originally somewhere else, but overwritten on
m68k (and a few others)?

    arch/arm/kernel/ptrace.c:       .name = "arm", .e_machine =
ELF_ARCH, .ei_osabi = ELF_OSABI,
    arch/hexagon/kernel/ptrace.c:   .ei_osabi = ELF_OSABI,
    arch/m68k/kernel/ptrace.c:      .ei_osabi = ELF_OSABI,
    arch/mips/kernel/ptrace.c:      .ei_osabi       = ELF_OSABI,
    arch/mips/kernel/ptrace.c:      .ei_osabi       = ELF_OSABI,
    arch/mips/kernel/ptrace.c:      .ei_osabi       = ELF_OSABI,
    arch/nios2/kernel/ptrace.c:     .ei_osabi = ELF_OSABI,

Does this work on other architectures?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds