Hi Juergen,
Thanks for your reply.
Please correct me if I'm wrong here, but from what you are saying, if my
flash has a block
size of 512KB (thats the erase size also) and I define the env partition
to have say 5 blocks with one that is bad
I'm covered if I do my read/write operations using a bb device.
Also, say a block gets wear out after extended use, will it be marked
bad after a failed write operation for example?
I think the quiestion above is actually if Barebox can handle a block
going bad in it's environment?
Thanks,
Boaz.
On 06/05/11 15:11, Juergen Beisert wrote:
Hi,
Boaz Ben-David wrote:
I want to protect the env partition on my device from bad blocks
(created during operation or already there out of the factory).
Maybe you mean the same, but you cannot really _protect_ them from bad blocks.
Couldn't find any good documentation regarding this issue, so I have
some questions:
1. Exactly what capabilities the bb devices in Barebox give me?
Handling a flash based memory in a linear manner, even if there are "holes" in
the memory.
non-bb |---------------------|BB|------------------------------|
|---ESU--|
bb |-----------------------------------------------|
Reading the "non-bb" will give you an error message, when you try to read from
the offset the BadBlock is located. Reading the "bb" silently skips the
BadBlock for you. By the price the usable size is smaller.
ESU is a "erase size unit" you always will lose if it contains a bad block.
2. I was thinking of somehow assigning the env partition larger than
required in order to later
handle bad blocks by moving the block currenly being used to be the
first good block.
Is this a good approach or maybe there is something already ready and I
shouldn't bother because I am totally missing the point?
You should increase the partitions in "erase block size units". Recent NAND
flashes are using 128 kiB erase size units. So, increasing by 256 kiB will
give you two spare "erase block size units".
jbe
_______________________________________________
barebox mailing list
barebox@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/barebox
