[Letux-kernel] Subtle issue with U-Boot and kernel and SD card UUIDs

H. Nikolaus Schaller hns at goldelico.com
Tue May 23 15:54:51 CEST 2017


Hi Matthijs,

> Am 23.05.2017 um 15:07 schrieb Matthijs van Duin <matthijsvanduin at gmail.com>:
> 
> On 23 May 2017 at 10:42, H. Nikolaus Schaller <hns at goldelico.com> wrote:
> This is not at all wrong and should do what it is intended for: map the mmc
> device numbers from U-Boot in a way that the kernel can assign a different
> order (and it does!).
> 
> Of course you already know that can be easily fixed with two tiny patches that are in my tree

Hm. No, I don't know that. Otherwise I would not ask...

Did you announce that fix to the greater public (so that I have a chance to get known to it)?
Or do you expect me to track your private git repo for changes?

> 
> 
> On 23 May 2017 at 10:42, H. Nikolaus Schaller <hns at goldelico.com> wrote:
> Now how can they have the same UUID? It should be unique, shouldn't it?
> 
> When a pc-style partition table is used, PARTUUIDs don't really exist and $DISKID-$N is used as substitute, where the disk id is extracted from the partition table and N is the partition number.

Yes, that is what I have found out in the meantime.

> 
> As for why the disk id is zero for your cards I dunno. You should be able to reset them to a random number by generating a new partition table using fdisk.

They were created by sfdisk and maybe it does not define it properly/randomly...

> 
> And there, we have nice UUIDs!
> 
> You're confusing partition UUIDs (PARTUUID) with filesystem UUIDs. The kernel only understands the former, while blkid is showing you the latter.

Yes, that makes sense...

BR and thanks,
Nikolaus



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