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From: Peter Maydell <peter.maydell@linaro.org>
Date: Tue, 9 Sep 2014 19:02:42 +0100
Message-ID: <CAFEAcA-WesMDCW7fjVmoTC9q4Zx27OtrAp4b3Mj_bqKJsGTB0Q@mail.gmail.com>
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Subject: Re: [Qemu-devel] [PATCH 3/6] hw/arm/boot: load device tree to base
 of DRAM if no -kernel option was passed
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To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Fu Wei <fu.wei@linaro.org>, QEMU Developers <qemu-devel@nongnu.org>, Christoffer Dall <christoffer.dall@linaro.org>

On 5 September 2014 16:15, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> If we are running the 'virt' machine, we may have a device tree blob but no
> kernel to supply it to if no -kernel option was passed. In that case, copy it
> to the base of RAM where it can be picked up by a bootloader.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  hw/arm/boot.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
> index c103a8fdc941..8f5649a250fd 100644
> --- a/hw/arm/boot.c
> +++ b/hw/arm/boot.c
> @@ -463,6 +463,16 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
>
>      /* Load the kernel.  */
>      if (!info->kernel_filename) {
> +
> +        if (have_dtb(info)) {
> +            /* If we have a device tree blob, but no kernel to supply it to,
> +             * copy it to the base of RAM for a bootloader to pick up.
> +             */
> +            if (load_dtb(info->loader_start, info, NULL)) {
> +                exit(1);
> +            }
> +        }
> +
>          /* If no kernel specified, do nothing; we will start from address 0
>           * (typically a boot ROM image) in the same way as hardware.
>           */
> --
> 1.8.3.2

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

(though obviously if you change the load_dtb() arg/return
this will need tweaking slightly).

-- PMM