[U-Boot-Users] JFFS2+U-Boot writing an image that has been "SUMMARY"-patched?

[U-Boot-Users] JFFS2+U-Boot writing an image that has been "SUMMARY"-patched?

[Dave Ellis]

Martin Egholm Nielsen wrote:
> I'm considering patching my Linux kernel JFFS2 code with the "summary"

> patch:
> http://www.inf.u-szeged.hu/jffs2/mount.php
> decreasing mount time severely. In short, this patch requires
modifying 
> some data in the end of each eraseblock - also in the image that
should 
> be written.
> 
> However, I'm planning on using u-boot to write the Linux root-fs -
using 
> "nand write.jffs2" - and was wondering whether this function 
> (write.jffs2) actually cared about what it was writing?

When I added the option all it did was allow skipping of bad blocks
(since
JFFS2 blocks don't care where they are in the FLASH) and write the oob
data properly for JFFS2. It didn't (and I think still doesn't) examine
the
JFFS2 data at all. As long as the summary data is location independent
it
should be OK.
 
> I tried writing "giberish" memory data using write.jffs2, and it
didn't 
> complain, though. But still, its name ".jffs2" indicate that some 
> knowledge of jffs2 is used?

I only meant it to indicate that the option is for writing jffs2 images,
so
if changes or added features would break jffs2 compatibility (and some
were
proposed a while ago) the changes should not be made to the jffs2
option, they
would need a new one.

Best regards,

Dave Ellis
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[U-Boot-Users] Re: JFFS2+U-Boot writing an image that has been "SUMMARY"-patched?

[Martin Egholm Nielsen]

Hi Dave,

>>I'm considering patching my Linux kernel JFFS2 code with the "summary"
>>patch:
>>http://www.inf.u-szeged.hu/jffs2/mount.php
>>decreasing mount time severely. In short, this patch requires modifying 
>>some data in the end of each eraseblock - also in the image that should 
>>be written.

>>However, I'm planning on using u-boot to write the Linux root-fs - using 
>>"nand write.jffs2" - and was wondering whether this function 
>>(write.jffs2) actually cared about what it was writing?

> When I added the option all it did was allow skipping of bad blocks 
> (since JFFS2 blocks don't care where they are in the FLASH) and write
> the oob data properly for JFFS2. It didn't (and I think still
> doesn't) examine the JFFS2 data at all. As long as the summary data
> is location independent it should be OK.
Super, I kinda guessed that!

>> I tried writing "giberish" memory data using write.jffs2, and it 
>> didn't complain, though. But still, its name ".jffs2" indicate that
>> some knowledge of jffs2 is used? >
> I only meant it to indicate that the option is for writing jffs2
> images, so if changes or added features would break jffs2
> compatibility (and some were proposed a while ago) the changes should
> not be made to the jffs2 option, they would need a new one. >
Makes sense!

Thanks for sorting that out - I'll head for jffs2+summary now, then...

// Martin

[U-Boot-Users] Re: JFFS2+U-Boot writing an image that has been "SUMMARY"-patched?

[C Michael Sundius]

>>> I'm considering patching my Linux kernel JFFS2 code with the 
>>> "summary"
>>> patch:
>>> http://www.inf.u-szeged.hu/jffs2/mount.php
>>> decreasing mount time severely. In short, this patch requires 
>>> modifying some data in the end of each eraseblock - also in the 
>>> image that should be written.



by the way has anyone tried to put support in U-boot for the other 
JFFS2 Improvement project that they
people at Szeged did? i.e. that uses other compression algorithms?

http://www.inf.u-szeged.hu/jffs2/bbc.php

C Michael Sundius
Solico Group LLC
232 Nevada St
San Francisco, CA 94110
msundius at sundius.com
(415)608-0121