Module loading problem in joyride?

[Deepak Saxena]

On Nov 22 2008, at 08:40, Mitch Bradley was caught saying:
> There are two things that could have changed - either RTIME compression 
> was added to the mkfs.jffs2 configuration, or it was removed from the 
> kernel configuration (or both).  My best guess is that it was removed 
> from the kernel at some point, because I know that, at least at one 
> point in OLPC's past, RTIME compression was enabled.  I know this 
> because there was an OFW bug in which OFW encountered an 
> RTIME-compressed node and couldn't handle it.  OFW now supports RTIME 
> decompression.

Your guess is correct. I got overzealous when I disabled LZO and
disabled RTIME in the config.

> The best solution would be:
> 
> a) In mkfs.jffs2, turn off RTIME compression so it is never used in 
> pristine filesystems
> b) In the kernel, enable both CONFIG_JFFS2_RTIME and JFFS2_CMODE_PRIORITY
> 
> The suggested kernel setting makes the RTIME decompressor available if 
> needed, but ensures that when zlib (higher priority) succeeds, the 
> kernel won't waste time on RTIME.  There's still some time wasted when 
> zlib can't reduce the size - instead of just punting and storing an 
> uncompressed node, it will try RTIME.  Ideally, it would be better to 
> disable RTIME decompression entirely, so as not to waste that time.  
> While there is a #define to do that - JFFS2_RTIME_DISABLED - I see no 
> Kconfig option to control it at that .config level.

There is CONFIG_JFFS2_RTIME option. Will re-enable it and and push to 
master.  I agree that ideally we should just disable it but as per Daniel's
experience this will break unless we change the mkfs.jffs2 option.
Even if we do the later, it will lead to issues if someone tries to 
mix and match new kernels with older builds.

~Deepak


-- 
 Deepak Saxena - Kernel Developer, One Laptop Per Child
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