fun with SD cards

[Owen Williams]

So I took a chance and bought a 4 gig SD card
(http://www.newegg.com/product/product.asp?item=N82E16820163159).  

I thought it wasn't working...

Dec  6 17:11:10 localhost kernel: mmcblk0: mmc0:b368 SDC   4020224KiB 
Dec  6 17:11:10 localhost kernel:  mmcblk0:<3>mmcblk0: error 1 transferring data
Dec  6 17:11:10 localhost kernel: end_request: I/O error, dev mmcblk0, sector 0
Dec  6 17:11:10 localhost kernel: Buffer I/O error on device mmcblk0, logical block 0
Dec  6 17:11:10 localhost kernel:  unable to read partition table

but then I ejected and reinserted and noticed /dev/mmcblk0
and /dev/mmcblk0p1.  I mounted, and there it was:

/dev/mmcblk0p1   3.8G   7.7M 3.6G 1% /media/4GSD

Right now it's an ext2 drive, but I'd like to make it jffs2 instead.
How do I create a jffs2 filesystem?  the documentation is really
confusing and the mkfs.jffs2 wants to make a tree from existing files.

owen