[PATCH] efi: efi-stub: notify on DTB absence

[Ard Biesheuvel]

On 20 October 2014 20:29, Mark Rutland <mark.rutland at arm.com> wrote:
> In the absence of an DTB configuration table, the EFI stub will happily
> continue attempting to boot a kernel, despite the fact that this kernel
> may not function without a description of the hardware. In this case, as
> with a typo'd "dtb=" option (e.g. "dbt=") or many other possible
> failures, the only output seen by the user will be the rather terse
> output from the EFI stub:
>
> EFI stub: Booting Linux Kernel...
>
> To aid those attempting to debug such failures, this patch adds a notice
> when no DTB is found, making the output more helpful:
>
> EFI stub: Booting Linux Kernel...
> EFI stub: Generating empty DTB
>
> Similarly, a positive acknowledgement is added when a user-specified DTB
> is in use:
>
> EFI stub: Booting Linux Kernel...
> EFI stub: Using DTB from command line
>
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Acked-by: Leif Lindholm <leif.lindholm at linaro.org>

Acked-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>

> Cc: Mark Salter <msalter at redhat.com>
> Cc: Matt Fleming <matt.fleming at intel.com>
> Cc: Roy Franz <roy.franz at linaro.org>
> ---
>  drivers/firmware/efi/libstub/arm-stub.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
> index 480339b..10abf24 100644
> --- a/drivers/firmware/efi/libstub/arm-stub.c
> +++ b/drivers/firmware/efi/libstub/arm-stub.c
> @@ -243,9 +243,16 @@ unsigned long __init efi_entry(void *handle, efi_system_table_t *sys_table,
>                         goto fail_free_cmdline;
>                 }
>         }
> -       if (!fdt_addr)
> +
> +       if (fdt_addr) {
> +               pr_efi(sys_table, "Using DTB from command line\n");
> +       } else {
>                 /* Look for a device tree configuration table entry. */
>                 fdt_addr = (uintptr_t)get_fdt(sys_table);
> +       }
> +
> +       if (!fdt_addr)
> +               pr_efi(sys_table, "Generating empty DTB\n");
>
>         status = handle_cmdline_files(sys_table, image, cmdline_ptr,
>                                       "initrd=", dram_base + SZ_512M,
> --
> 1.9.1
>