Re: [Qemu-devel] [PATCH v2 4/4] hw/arm/boot: enable DTB support when booting ELF images

[Peter Maydell]

On 10 September 2014 11:59, Ard Biesheuvel <address@hidden> wrote:
> Add support for loading DTB images when booting ELF images using
> -kernel. If there are no conflicts with the placement of the ELF
> segments, the DTB image is loaded at the base of RAM.
>
> Signed-off-by: Ard Biesheuvel <address@hidden>
> ---
>  hw/arm/boot.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
> index 1f73614d8843..3878cbd97aad 100644
> --- a/hw/arm/boot.c
> +++ b/hw/arm/boot.c
> @@ -464,7 +464,7 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info 
> *info)
>      int kernel_size;
>      int initrd_size;
>      int is_linux = 0;
> -    uint64_t elf_entry;
> +    uint64_t elf_entry, elf_low_addr;
>      int elf_machine;
>      hwaddr entry, kernel_load_offset;
>      int big_endian;
> @@ -531,7 +531,19 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info 
> *info)
>
>      /* Assume that raw images are linux kernels, and ELF images are not.  */
>      kernel_size = load_elf(info->kernel_filename, NULL, NULL, &elf_entry,
> -                           NULL, NULL, big_endian, elf_machine, 1);
> +                           &elf_low_addr, NULL, big_endian, elf_machine, 1);
> +    if (kernel_size > 0 && have_dtb(info)) {
> +        /* If there is still some room left between the base of RAM and the
> +         * low end of the ELF image we just loaded, try and put the DTB at 
> the
> +         * base of RAM like we do for bootloaders. Just ignore the potential > 0
> +         * return value of load_dtb() which indicates that the dtb didn't 
> fit,
> +         * in that case we just proceed without it.
> +         */
> +        if (elf_low_addr > info->loader_start &&
> +            load_dtb(info->loader_start, info, elf_low_addr) < 0) {
> +            exit(1);
> +        }
> +    }

The conditional means we won't try to load the DTB even if the
ELF file fit into the address space entirely below loader_start,
which doesn't look right.

thanks
-- PMM