Comparing UBI volumes to generate patch for upgrades

[Subodh Nijsure]

On 02/03/2012 01:18 AM, Artem Bityutskiy wrote:
> On Wed, 2012-02-01 at 10:31 -0800, Subodh Nijsure wrote:
>> one option is  use VCDIFF/bsdif or variation there-of and generate a
>> binary diff package.
>>
>> option 2 is write a tool that compares UBI volume layout for revision 1
>> and UBI volume layout for revision 2 and then send that difference,
>> along the lines of what is outlined in the paper @
>> http://www.icmu.org/icmu2010/Papers/3-1.pdf
> I guess you can do this for R/O volumes, but not R/W.
Yes we would do this 'upgrade' on read-only volume.
>
> Depending on how much extra flash you have, you may do the actual update
> in a power-off-tolerant manner or not.
Actually we do have to do this upgrade in power-off-tolerant manner, but 
hardware does give us few seconds of "battery backed" power, and 
indicates to software that shutdown is imminent.
>> We are just getting started writing a tool to compare UBI volumes, but I
>> want to send out querry to UBI experts to see if there are some
>> fundamental issues with UBI that would make comparing UBI volumes and
>> applying such a patch would be a non-starter.
> I assume you are not planning to do this stuff in kernel space, right?
Not planning to this in kernel space.