Messages in this thread | | | Date | Fri, 13 Sep 2013 14:09:55 -0400 | From | Matt Porter <> | Subject | Re: GPT detection regression in efi.c from commit 27a7c64 |
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On 09/13/2013 02:07 PM, Davidlohr Bueso wrote: > On Fri, 2013-09-13 at 13:01 -0400, Matt Porter wrote: >> On 09/13/2013 12:28 PM, Davidlohr Bueso wrote: >>> Cc'ing Linus. >>> >>> On Fri, 2013-09-13 at 10:50 -0400, Matt Porter wrote: >>>> The commit, "27a7c64 partitions/efi: account for pmbr size in lba", that >>>> was just merged in 3.12-rc caused a regression on my system with a GPT >>>> formatted eMMC device. In 3.11, the GPT partition table was detected >>>> fine but now a partition table is not detected. >>>> >>>> Not being a GPT expert, I did some research and found that the tool used >>>> to create the PMBR on my system shares characteristics with what is >>>> mentioned in an explanation of Microsoft created PMBRs [1]. In short, >>>> the size_in_lba field incorrectly has 0xffffffff even though I have a >>>> <2TiB drive (16GiB eMMC). >>> >>> *sigh*. So Microsoft decided to do its own version of the GPT specs. >> >> Don't sound so surprised. :) >> >>> Up until now, Linux was incorrectly enforcing pMBR checks: not >>> recognizing valid labels and vice versa, as with the case you are >>> mentioning now. The changes that went in the 3.12 merge window attempt >>> to address those concerns, enforcing the correct checks - which is also >>> how Linux partitioning tools do it (fdisk, parted). >> >> Understood, and we are fixing our own manufacturing tool that was used >> to prepopulate the eMMC. I definitely prefer to have this correct for my >> case. > > 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.
-Matt
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