Re: [microblaze-uclinux] JFFS2 and MTD

[John Williams <jwilliams@itee.uq.edu.au>]

Robert Swindells wrote:
> 
>>I haven't - I saw that the output of mkfs.jffs2 when run on an empty 
>>directory was itself empty, so just figured I could mount straight on 
>>top of an empty mtdblock device.
> 
> Had you erased the area ?

Yes -
$ eraseall /dev/mtd6
$ mount -t jffs2 /dev/mtd6 /var

It is silent, no errors reported, but then the behaviour on trying to 
create files etc.

> 
> I don't think I have ever tried using a totally empty filesystem. I
> always created a small "seed" filesystem using mkfs.jffs2 containing
> a few files.

yep will give that a try

>>Also another thing that's probably related that I'm unsure about, when 
>>my board boots the JFFS2 driver is trying very hard to do something - I 
>>get a bunch of messages like this:
>>
> 
> The offsets look as if JFFS2 is using the wrong blocksize.

should the jffs2 block size be related to some physical parameter of the 
system?  What is the importance?


>>Is JFFS2 trying to mount some kind of default fdile system?  This is all 
>>happening before the shell starts, and before I can do any explicit 
>>mount -t jffs2 commands.
> 
> 
> It isn't trying to mount anything at this stage, it will just format
> up any blocks that are not marked as being already used. This works
> best if the unused blocks are cleared.

Sure - but how does the jffs2 module initialisation know which of the 
flash partitions are available for use?  e.g. the mtd5 (image) segment 
is not for jffs2, it is a raw kernel / filesys image.  I don't want 
jffs2 playing anywhere near it.

Should I be writing a partition table somewhere?

Thanks,

John

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