[U-Boot] [PATCH] disk: part_efi: add support for the Alternate GPT

[Steve Rae <srae@broadcom.com>]

Hmmm - perhaps "Secondary" would be more accurate wording than "Alternate"
(v2 coming...)

On 14-05-05 09:12 AM, Steve Rae wrote:
>
> On 14-05-05 03:50 AM, Przemyslaw Marczak wrote:
>> Hello Steve,
>>
>> On 04/30/2014 12:31 AM, Steve Rae wrote:
>>> Check the Alternate GPT table if the Primary GPT table is invalid.
>>>
>>> Signed-off-by: Steve Rae <srae@broadcom.com>
>>> ---
>>>
>>>   disk/part_efi.c | 20 ++++++++++++++++++--
>>>   1 file changed, 18 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/disk/part_efi.c b/disk/part_efi.c
>>> index 216a292..ad899fa 100644
>>> --- a/disk/part_efi.c
>>> +++ b/disk/part_efi.c
>>> @@ -93,7 +93,15 @@ void print_part_efi(block_dev_desc_t * dev_desc)
>>>       if (is_gpt_valid(dev_desc, GPT_PRIMARY_PARTITION_TABLE_LBA,
>>>                gpt_head, &gpt_pte) != 1) {
>>>           printf("%s: *** ERROR: Invalid GPT ***\n", __func__);
>>> -        return;
>>> +        if (is_gpt_valid(dev_desc, (dev_desc->lba - 1),
>>> +                 gpt_head, &gpt_pte) != 1) {
>>> +            printf("%s: *** ERROR: Invalid Alternate GPT ***\n",
>>> +                   __func__);
>>> +            return;
>>> +        } else {
>>> +            printf("%s: ***        Using Alternate GPT ***\n",
>>> +                   __func__);
>>> +        }
>>>       }
>>>
>>>       debug("%s: gpt-entry at %p\n", __func__, gpt_pte);
>>> @@ -142,7 +150,15 @@ int get_partition_info_efi(block_dev_desc_t * 
>>> dev_desc, int part,
>>>       if (is_gpt_valid(dev_desc, GPT_PRIMARY_PARTITION_TABLE_LBA,
>>>               gpt_head, &gpt_pte) != 1) {
>>>           printf("%s: *** ERROR: Invalid GPT ***\n", __func__);
>>> -        return -1;
>>> +        if (is_gpt_valid(dev_desc, (dev_desc->lba - 1),
>>> +                 gpt_head, &gpt_pte) != 1) {
>>> +            printf("%s: *** ERROR: Invalid Alternate GPT ***\n",
>>> +                   __func__);
>>> +            return -1;
>>> +        } else {
>>> +            printf("%s: ***        Using Alternate GPT ***\n",
>>> +                   __func__);
>>> +        }
>>>       }
>>>
>>>       if (part > le32_to_cpu(gpt_head->num_partition_entries) ||
>>>
>>
>> This looks ok, we can still use u-boot filesystem commands after gpt 
>> header block corruption, but the gpt is still...corrupted.
>>
>> Maybe we need additional gpt subcommand for restore gpt in case when 
>> backup of gpt header is valid?
>>
>> Actually we have only "gpt write" command but it needs proper 
>> environment variables. So I think that "gpt restore" is welcome.
>>
>> Thank you,
> Agree -- maybe I can find time to work on a "gpt restore" in the near 
> future....
> Thanks, Steve
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