Re: Bootloader support for UBI images

[Artem Bityutskiy <dedekind@infradead.org>]

On Wed, 2008-07-02 at 08:57 +0100, Richard Titmuss wrote:
> Right, I was thinking that it would allow any number of volumes for 
> renaming. I am also not sure about the interface, and was hoping to get 
> some suggestions here. I will think about it and propose something in a 
> few days.

Do you absolutely need multiple renames? Could you live with one at
a time?

> > So you use the sub-page read patch BTW?
> No, I'd missed that. Where is it?

Here is the relevant thread. Some people already use that patch. dwmw2
was positive about it and told he would accept it.

http://lists.infradead.org/pipermail/linux-mtd/2008-April/021412.html

> Ok, that is possible. This would also have to include the bad block and 
> bit flip status for each PEB. At the moment the Redboot flash api does 
> not make this available, so it would mean extending Redboot or writing 
> custom flash drivers to access this information.

Well, bit-flip information is not mandatory and may be done later as
an improvement. Bad-block information have to be available.

> > I did not actually catch the second part (LER and PER) tables - this is
> > something I am not aware of. UBI has only volume table on flash, the
> > other things are in-memory and build by scanning.
> >   
> It was a proposal to _add_ an addition table, that provided a LER to PER 
> mapping for static volumes.

Ah, this is s/LER/LEB/, s/PER/PEB/.

>  If this table was stored near the beginning 
> of the flash, then it could be accessed without a full scan. This could 
> only be used if the UBI volume was mounted read-only, any write 
> operations would require scanning all the flash blocks. This is an 
> alternative approach to passing data from the bootloader to the kernel.

Well, may be done, but the R/O limitation seems to be too hard.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)