[ECOS] jffs2 questions

Stanislav Meduna stano@meduna.org
Wed Jul 15 08:37:00 GMT 2009


Hi,

I am trying to use a JFFS2 filesystem in a serial dataflash
device. I encountered the jffs2_open hanging mysteriously,
so I started to investigate.

1) Reinitializing the filesystem resolved the hang.
   Is it possible that a corrupted filesystem (never
   unmounted in these tests, just powered down)
   causes the jffs to mount, but not open a file? From
   what I have read the unclean unmount should not cause
   this.

2) What is the stack usage of jffs2? Is it upper-bounded,
   or could it depend on the filesystem data? Is there
   an upper limit?

3) If I understand this correctly, jffs2 does not like
   small writes. I need to write a logfile into a flash -
   not too often (life of the flash is not an issue),
   but in small chunks. I thought I should use
   CONFIG_JFFS2_FS_WRITEBUFFER defined by CYGOPT_FS_JFFS2_NAND;
   however, the CDL states
     requires        0
   and I can not enable this. Huh?

4) CDL for CYGOPT_FS_JFFS2_GSTHREAD states
     Leave this off till it's been implemented. And don't
     implement it till icache locking has been made thread-safe.

   http://www.ecoscentric.com/ecospro/doc.cgi/html/ecospro-ref/fs-jffs2-usage.html
   just explains what it is and how it can be used. Does this
   mean that the eCosCentric version has other code than
   is in the CVS, or is just the CDL documentation obsolete?

Thanks
-- 
                                    Stano

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