linux-kernel - Re: GPT detection regression in efi.c from commit 27a7c64

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Message-ID: <52335A7A.6000406@linaro.org>
Date:	Fri, 13 Sep 2013 14:33:30 -0400
From:	Matt Porter <matt.porter@...aro.org>
To:	Davidlohr Bueso <davidlohr@...com>
CC:	Karel Zak <kzak@...hat.com>, Matt Fleming <matt.fleming@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	torvalds@...ux-foundation.org
Subject: Re: GPT detection regression in efi.c from commit 27a7c64

On 09/13/2013 02:29 PM, Davidlohr Bueso wrote:
> On Fri, 2013-09-13 at 20:17 +0200, Karel Zak wrote:
>> On Fri, Sep 13, 2013 at 02:09:55PM -0400, Matt Porter wrote:
>>>> Come to think of it, we do have a long existing workaround: the
>>>> force_gpt option. Setting it will bypass any MBR checking
>>>> (is_pmbr_valid(), specifically).
>>>
>>> Yes, that's what I used at first after seeing what the problem was. But then
>>> I opted to fix my PMBR.
>>>
>>> I felt like it was a regression since it required a new option passed on the
>>> cmdline.
>>
>>   Yep, it is *regression* and I guess Davidlohr is going to fix it asap :-)
>
> I was doing a git revert, but what would you guys think of keeping the
> check but making it more flexible? Instead of enforcing the minimum,
> just make sure that the size_in_lba is either the whole disk or 2 TiB,
> that should take care of Matt's issue.

That seems to be the way to go given the departure from the spec.

> diff --git a/block/partitions/efi.c b/block/partitions/efi.c
> index 1a5ec9a..df2fca1 100644
> --- a/block/partitions/efi.c
> +++ b/block/partitions/efi.c
> @@ -220,8 +220,8 @@ check_hybrid:
>           * Hybrid MBRs do not necessarily comply with this.
>           */
>          if (ret == GPT_MBR_PROTECTIVE) {
> -               if (le32_to_cpu(mbr->partition_record[part].size_in_lba) !=
> -                   min((uint32_t) total_sectors - 1, 0xFFFFFFFF))
> +               if (le32_to_cpu(mbr->partition_record[part].size_in_lba) != (uint32_t) total_sectors - 1 ||
> +                   le32_to_cpu(mbr->partition_record[part].size_in_lba) != 0xFFFFFFFF)
>                          ret = 0;
>          }
>   done:
>
> Karel, I guess any changes that we do here should apply to fdisk :)
>
> Thanks,
> Davidlohr
>

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