Re: Request for comments: UBI PEBs as a multiple of erase size

[Artem Bityutskiy <dedekind1@gmail.com>]

On Tue, 2011-09-13 at 12:36 -0700, Kevin Paul Herbert wrote:
> I came across a situation where I wanted to be able to use the same
> pre-built (with UBI) image on two different FLASH devices, one of
> which having a larger erase size than the other. I actually did not
> notice that the device I was using had a different erase size, which
> caused UBI to quietly corrupt my FLASH.
> 
> I have a patch to UBI (kernel and ubinize) to store the size of a PEB
> in the EC header, reject attaching if the PEB size is not equal to or
> an integer multiple of the erase size, and treat multiple erase blocks
> as a "cluster" for I/O operations.
> 
> I looked through a few months of archives to see if this is a common
> problem, and I don't see this as being discussed. Is there interest in
> me publishing this patch for inclusion in the kernel. The only
> downside I can see of my change is that it adds an additional 32 bit
> quantity to struct ubi_ec_hdr, reducing the available free header
> byets from 35 to 31. For backwards compatibility, if this field is
> zero, I treat it as PEB size == erase size.
> 
> It seems to me that having the PEB size in the header, regardless of
> supporting multiple erase blocks as a single PEB, is a useful
> consistency check.
> 
> Comments please?

I think we do have this kind of "protection" in UBIFS, but non in UBI.
Please, go ahead and send patches!

-- 
Best Regards,
Artem Bityutskiy