[U-Boot] [PATCH v3] x86: zImage: pass device tree setup data to the kernel

[Bin Meng]

Hi Ivan,

On Sat, Mar 17, 2018 at 8:32 AM, Ivan Gorinov <ivan.gorinov at intel.com> wrote:
> On x86 platforms, U-Boot does not provide Device Tree data to the kernel.
> This prevents the kernel from using the same hardware description.
>
> Make a copy of DTB data with setup_data header and insert new item
> into the the setup data linked list.
>

So this means the Linux kernel reuses the same DTB as what is used by
U-Boot. However U-Boot's DTB contains a lot of stuff which is only
useful for bootloader, like the microcode stuff.

Like other arch's bootm command, should we allow a separate DTB (which
is only used by the kernel) passed to the 'zboot' command?

> Signed-off-by: Ivan Gorinov <ivan.gorinov at intel.com>
> ---
>  arch/x86/include/asm/bootparam.h |  7 +++++--
>  arch/x86/lib/zimage.c            | 31 +++++++++++++++++++++++++++++++
>  2 files changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/bootparam.h b/arch/x86/include/asm/bootparam.h
> index 90768a9..6aba614 100644
> --- a/arch/x86/include/asm/bootparam.h
> +++ b/arch/x86/include/asm/bootparam.h
> @@ -10,8 +10,11 @@
>  #include <asm/video/edid.h>
>
>  /* setup data types */
> -#define SETUP_NONE                     0
> -#define SETUP_E820_EXT                 1
> +enum {
> +       SETUP_NONE = 0,
> +       SETUP_E820_EXT,
> +       SETUP_DTB,
> +};
>
>  /* extensible setup data list node */
>  struct setup_data {
> diff --git a/arch/x86/lib/zimage.c b/arch/x86/lib/zimage.c
> index 2a82bc8..7e7ec5e 100644
> --- a/arch/x86/lib/zimage.c
> +++ b/arch/x86/lib/zimage.c
> @@ -14,6 +14,7 @@
>   */
>
>  #include <common.h>
> +#include <malloc.h>
>  #include <asm/acpi_table.h>
>  #include <asm/io.h>
>  #include <asm/ptrace.h>
> @@ -95,6 +96,35 @@ static int get_boot_protocol(struct setup_header *hdr)
>         }
>  }
>
> +static int setup_device_tree(struct setup_header *hdr)
> +{
> +       const void *fdt_blob = gd->fdt_blob;
> +       struct setup_data *sd;
> +       int size;
> +
> +       if (!fdt_blob)
> +               return 0;
> +
> +       size = fdt_totalsize(fdt_blob);
> +       if (size < 0)
> +               return -EINVAL;
> +
> +       size += sizeof(struct setup_data);
> +       sd = (struct setup_data *)malloc(size);
> +       if (!sd) {
> +               printf("Not enough memory for DTB setup data\n");
> +               return -ENOMEM;
> +       }
> +
> +       sd->next = hdr->setup_data;
> +       sd->type = SETUP_DTB;
> +       sd->len = fdt_totalsize(fdt_blob);
> +       memcpy(sd->data, fdt_blob, sd->len);
> +       hdr->setup_data = (unsigned long)sd;
> +
> +       return 0;
> +}
> +
>  struct boot_params *load_zimage(char *image, unsigned long kernel_size,
>                                 ulong *load_addressp)
>  {
> @@ -262,6 +292,7 @@ int setup_zimage(struct boot_params *setup_base, char *cmd_line, int auto_boot,
>  #endif
>
>         setup_video(&setup_base->screen_info);
> +       setup_device_tree(hdr);
>
>         return 0;
>  }
> --

Regards,
Bin