UBI: ignore/overwrite old data/PEBs after flashing

[Rafał Miłecki]

On 16 October 2014 11:10, Richard Weinberger
<richard.weinberger at gmail.com> wrote:
> On Thu, Oct 16, 2014 at 7:34 AM, Rafał Miłecki <zajec5 at gmail.com> wrote:
>> Hi,
>>
>> I need some help with flashing UBI images.
>>
>> I work with Broadcom ARM SoCs that use a CFE bootloader. In most cases
>> it doesn't provide a way to clear flash content before flashing the
>> firmware. It means that if I have 120 MiB of space for the firmware
>> and I flash 20 MiB firmware, the rest of flash (100 MiB) won't be
>> cleared. My partitioner driver will create 2 MiB partition for kernel
>> and 118 MiB partition for UBI.
>>
>> So the result is that UBI partition contains 18 MiB of prebuilt
>> (ubinize-d) image and 100 MiB of rubbish. This will lead to problems
>> like:
>> UBI warning: scan_peb: valid VID header but corrupted EC header at PEB 17
>>
>> UBI will find some old PEBs, try to use them, this may even lead to
>> situation where the data from previous install will be still
>> available!
>>
>>
>> Of course, I'm aware I should not upgrade my images this way all the
>> time. Normally I would simply use
>> $ ubiformat /dev/mtd0 -f ubi.img
>> , but I'm trying to handle some corner cases. Sometimes the firmware
>> may be broken and user may not be able to boot. In such case I need to
>> be able to re-flash the firmware using bootloader (and sacrifice the
>> wearing info).
>>
>>
>> Is there some way to tell UBI to ignore & overwrite all flash data
>> (including PEBs) that are placed after the flashed (ubinize-d) image?
>> Could we add some magic PEB that will tell UBI that all the flash
>> content after that single PEB is rubbish?
>
> I'm confused. Do you always use the same UBI sequence number?
> If you flash only 20MiB why do you create a much larger MTD partition?

I tried to explain everything, but ofc forgot about this.

The answer is:
vol_flags=autoresize
I create much bigger MTD partition, because I want UBI to resize my
partition (to let user use whole flash space).

-- 
Rafał