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

[Simon Glass]

On 18 March 2018 at 21:38, Bin Meng <bmeng.cn at gmail.com> wrote:
> 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?

Yes I think so. Probably this needs another arg to zboot.

Also we do support FIT boot on x86 so should make sure that the DT can
be passed in that case too.

>
>> 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

Regards,
Simon