[PATCH] disk: part_efi: update partition table entries after write

[Heinrich Schuchardt]

On 1/27/21 7:33 AM, AKASHI Takahiro wrote:
> On Tue, Jan 26, 2021 at 04:08:13PM +0100, Heinrich Schuchardt wrote:
>> On 26.01.21 14:56, Gary Bisson wrote:
>>> Fixes fastboot issues when switching from mbr to gpt partition tables.
>>>
>>> Signed-off-by: Gary Bisson <gary.bisson at boundarydevices.com>
>>> ---
>>> Hi,
>>>
>>> I hesitated calling this a RFC as I'm not sure everyone will like the
>>> idea.
>>>
>>> Basically the issue encountered was the following:
>>> - Device with its storage flashed with a MBR partition table
>>> - Run fastboot to flash a new OS (and new partition table)
>>> - After flashing a GPT partition table, U-Boot couldn't find any of the
>>>    partition names from the GPT
>>>    -> reason is that the partition table entries aren't updated
>>>    -> so U-Boot still believes it's a MBR table inside and so its parsing
>>>    fails
>>>
>>> This commit adds an update of the table entries inside the
>>> write_mbr_and_gpt_partitions() function. At first I thought maybe this
>>> should be added in fastboot file (fb_mmc.c) but couldn't think of a good
>>> reason why this shouldn't happened in part_efi directly.
>>>
>>> Let me know if you have any questions.
>>>
>>> Regards,
>>> Gary
>>> ---
>>>   disk/part_efi.c | 3 +++
>>>   1 file changed, 3 insertions(+)
>>>
>>> diff --git a/disk/part_efi.c b/disk/part_efi.c
>>> index 2f922662e6e..7a24e33d189 100644
>>> --- a/disk/part_efi.c
>>> +++ b/disk/part_efi.c
>>> @@ -867,6 +867,9 @@ int write_mbr_and_gpt_partitions(struct blk_desc *dev_desc, void *buf)
>>>   		return 1;
>>>   	}
>>>
>>> +	/* Update the partition table entries*/
>>> +	part_init(dev_desc);
>>> +
>>>   	return 0;
>>>   }
>>>   #endif
>>>
>>
>> This change is for GPT only. Don't we need the same for MBR partition
>> tables (write_mbr_partitions())?
>>
>> @Simon:
>>
>> Essentially this reflashing is similar to changing media. What I am
>> missing in part_init() is setting a field with a counter to indicate the
>> media change. The EFI_BLOCK_IO_PROTOCOL has a u32 field media_id. Would
>> struct blk_desc be the right place to add such a field.
>
> As far as "efi_loader" is concerned, none of partitions on the media,
> either in case of repartitioning or changing media, will no longer be
> recognized as a "efi disk" after efi subsystem is initialized.
> All we can and have to do is to just reboot the system.
>
> I think we should take one step further to fixing the issue along with
> this patch. I have posted a couple of proposals in the past, for example,
> see [1].
>
> [1] https://lists.denx.de/pipermail/u-boot/2019-January/356499.html

We have a deficiency in the UEFI sub-system with adding and removing
block devices. But this is not a problem of Gary's patch.

So from my side:

Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>