Re: [Qemu-devel] [PATCH v2 1/2] ARM: Allow boards to provide an fdt blob

[Peter Maydell]

On 30 April 2013 17:04, John Rigby <address@hidden> wrote:
> If no fdt is provided on command line and the new field
> get_dtb in struct arm_boot_info is set then call it to
> get a device tree blob.
>
> Also allow dumping of device tree by calling qemu_devtree_dumpdtb
> near the end of load_dtb.

"Also ..." in a commit message is usually a clue that you
should split the patch :-)

> Signed-off-by: John Rigby <address@hidden>
> ---
>  hw/arm/boot.c        |   31 ++++++++++++++++++++-----------
>  include/hw/arm/arm.h |    6 ++++++
>  2 files changed, 26 insertions(+), 11 deletions(-)
>
> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
> index f451529..de71edf 100644
> --- a/hw/arm/boot.c
> +++ b/hw/arm/boot.c
> @@ -235,19 +235,27 @@ static int load_dtb(hwaddr addr, const struct 
> arm_boot_info *binfo)
>      int size, rc;
>      uint32_t acells, scells, hival;
>
> -    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, binfo->dtb_filename);
> -    if (!filename) {
> -        fprintf(stderr, "Couldn't open dtb file %s\n", binfo->dtb_filename);
> -        return -1;
> -    }
> +    if (binfo->dtb_filename) {
> +        filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, binfo->dtb_filename);
> +        if (!filename) {
> +            fprintf(stderr, "Couldn't open dtb file %s\n", 
> binfo->dtb_filename);
> +            return -1;
> +        }
>
> -    fdt = load_device_tree(filename, &size);
> -    if (!fdt) {
> -        fprintf(stderr, "Couldn't open dtb file %s\n", filename);
> +        fdt = load_device_tree(filename, &size);
> +        if (!fdt) {
> +            fprintf(stderr, "Couldn't open dtb file %s\n", filename);
> +            g_free(filename);
> +            return -1;
> +        }
>          g_free(filename);
> -        return -1;
> +    } else if (binfo->get_dtb) {
> +        fdt = binfo->get_dtb(addr, binfo, &size);
> +        if (!fdt) {
> +            fprintf(stderr, "Couldn't get dtb blob from board func\n");

I think it's better to avoid being too abbreviated in error messages;
"Attempt to create dtb blob for this board model failed\n",
perhaps?

> +            return -1;
> +        }
>      }
> -    g_free(filename);
>
>      acells = qemu_devtree_getprop_cell(fdt, "/", "#address-cells");
>      scells = qemu_devtree_getprop_cell(fdt, "/", "#size-cells");
> @@ -304,6 +312,7 @@ static int load_dtb(hwaddr addr, const struct 
> arm_boot_info *binfo)
>              fprintf(stderr, "couldn't set /chosen/linux,initrd-end\n");
>          }
>      }
> +    qemu_devtree_dumpdtb(fdt, size);
>
>      cpu_physical_memory_write(addr, fdt, size);
>
> @@ -440,7 +449,7 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info 
> *info)
>          /* for device tree boot, we pass the DTB directly in r2. Otherwise
>           * we point to the kernel args.
>           */
> -        if (info->dtb_filename) {
> +        if (info->dtb_filename || info->get_dtb) {
>              /* Place the DTB after the initrd in memory. Note that some
>               * kernels will trash anything in the 4K page the initrd
>               * ends in, so make sure the DTB isn't caught up in that.
> diff --git a/include/hw/arm/arm.h b/include/hw/arm/arm.h
> index 7b2b02d..4c56a1b 100644
> --- a/include/hw/arm/arm.h
> +++ b/include/hw/arm/arm.h
> @@ -31,6 +31,10 @@ struct arm_boot_info {
>      const char *kernel_cmdline;
>      const char *initrd_filename;
>      const char *dtb_filename;
> +    /* if a board is able to create a dtb without a dtb file then it
> +     * sets get_dtb.  This will only be used if no dtb file is provided.
> +     */
> +    void *(*get_dtb)(hwaddr addr, const struct arm_boot_info *binfo, int 
> *size);
>      hwaddr loader_start;
>      /* multicore boards that use the default secondary core boot functions
>       * need to put the address of the secondary boot code, the boot reg,
> @@ -59,6 +63,8 @@ struct arm_boot_info {
>      int is_linux;
>      hwaddr initrd_start;
>      hwaddr initrd_size;
> +    void *dtb_blob;
> +    int dtb_blob_size;

The get_dtb function returns the blob and its size via
the hook's arguments, so what are these extra fields for?

>      hwaddr entry;
>  };
>  void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info);
> --
> 1.7.9.5
>

thanks
-- PMM