Different erase block sizes in a JFFS2 partion.

Different erase block sizes in a JFFS2 partion.

[Joakim Tjernlund]

Got multiple NOR chips with top and bottom boot blocks with diffrent EB size
then the rest of the blocks. 
I want to put a JFFS2 FS spanning over several chips which makes the FS
cross top/bottom boot blocks.
Since(last I looked) JFFS2 can't deal with diffrent EB sizes on the same
partition I need do something about it.
I want to use point()/unpoint() and a cached memory mapping for burst access
and I don't know how to do that yet and I would like some ideas.

One idea I have is to reserve the boot blocks with a new type of JFFS2
node(similar to JFFS2_FEATURE_ROCOMPAT) that spans the whole boot block.
JFFS2 should not try to move or delete nodes of this type. Not sure
if thats a good idea or if its hard to impl. yet.

Better ideas anyone?

Re: Different erase block sizes in a JFFS2 partion.

[Josh Boyer]

On 9/28/06, Joakim Tjernlund <joakim.tjernlund@transmode.se> wrote:
> Got multiple NOR chips with top and bottom boot blocks with diffrent EB size
> then the rest of the blocks.

Intel P30?  IIRC, the MTD driver maps those into a set of larger
virtual eraseblocks.  You might not be able to even distinguish that
they exist.

josh

Re: Different erase block sizes in a JFFS2 partion.

[Joakim Tjernlund]

Josh Boyer wrote:
> On 9/28/06, Joakim Tjernlund <joakim.tjernlund@transmode.se> wrote:
>> Got multiple NOR chips with top and bottom boot blocks with diffrent EB size
>> then the rest of the blocks.
> 
> Intel P30?  IIRC, the MTD driver maps those into a set of larger
> virtual eraseblocks.  You might not be able to even distinguish that
> they exist.

yes, Intel P30.
The cfi_cmdset_0001 driver maps them like this:
0: offset=0x0,size=0x8000,blocks=4
1: offset=0x20000,size=0x20000,blocks=255
2: offset=0x2000000,size=0x8000,blocks=4
3: offset=0x2020000,size=0x20000,blocks=255

First, this map is wrong. 2: and 3: should be swapped, that is,
the small blocks should be at the end of the device.

the small blocks fits into a larger one so I should have no problem reading/writing
to such virtual block, but I don't think erase will work as JFFS2 will
only erase one of the small blocks instead of all 4. Maybe I am missing something?