Re: [Qemu-devel] [RFC PATCH] elf loader: exit if incompatible architecture is detected

[Alexander Graf <agraf@suse.de>]

On 07.01.2014, at 05:35, Alexey Kardashevskiy <aik@ozlabs.ru> wrote:

> If we know for sure that the image in "-kernel" is an ELF and we know its
> architecture and it is not supported by the current QEMU, there is no
> point to continue trying booting this image so let's exit once we deteced
> this fact.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

How about we just remove non-ELF loading from -kernel on -M pseries?


Alex

> ---
> 
> 
> One of our users tried an X86 image with qemu-system-ppc64. Instead of
> printing some reasonable message (which is possible in this case as the image
> is ELF), QEMU (spapr.c) simply copied the image in RAM as a raw image and
> SLOF failed to boot from it.
> 
> The patch fixes the issue but there are still questions.
> 
> 1. Do we need more sophisticated error checking here? Return -2 instead of exit(1)
> and do exit(1) few levels up?
> 
> 2. The patch does not handle x86's vmlinuz case - these images are not ELFs
> but "Linux kernel x86 boot executable bzImage" and QEMU does not parse them.
> As a result, SLOF crashes with the registers dump. Do we really care to handle this?
> 
> 
> ---
> include/hw/elf_ops.h | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h
> index acc701e..6bcc61f 100644
> --- a/include/hw/elf_ops.h
> +++ b/include/hw/elf_ops.h
> @@ -212,21 +212,21 @@ static int glue(load_elf, SZ)(const char *name, int fd,
>         case EM_PPC64:
>             if (EM_PPC64 != ehdr.e_machine)
>                 if (EM_PPC != ehdr.e_machine)
> -                    goto fail;
> +                    goto arch_fail;
>             break;
>         case EM_X86_64:
>             if (EM_X86_64 != ehdr.e_machine)
>                 if (EM_386 != ehdr.e_machine)
> -                    goto fail;
> +                    goto arch_fail;
>             break;
>         case EM_MICROBLAZE:
>             if (EM_MICROBLAZE != ehdr.e_machine)
>                 if (EM_MICROBLAZE_OLD != ehdr.e_machine)
> -                    goto fail;
> +                    goto arch_fail;
>             break;
>         default:
>             if (elf_machine != ehdr.e_machine)
> -                goto fail;
> +                goto arch_fail;
>     }
> 
>     if (pentry)
> @@ -306,4 +306,9 @@ static int glue(load_elf, SZ)(const char *name, int fd,
>     g_free(data);
>     g_free(phdr);
>     return -1;
> +
> +arch_fail:
> +    fprintf(stderr, "qemu: could not load arch-incompatible kernel '%s'\n",
> +            name);
> +    exit(1);
> }
> -- 
> 1.8.4.rc4
>