running OS off mmc card - why ext2 filing system?
 

I just installed fanoush's initfs so I could choose what to boot, and copied the file system to the MMC card as specified in the old wiki (alternative 2)
https://maemo.org/community/wiki/how...428c68c35212e0
For some reason, I found the new wiki entry slightly less helpful. I'll see if I can tidy it up: https://wiki.maemo.org/Booting_from_a_flash_card

It worked first time, so I was pretty pleased!

Anyway, my question is this. Why does it say to use the "ext" file system on the memory card instead of jffs2? Surely jffs2 would be more efficient in space and be better suited to a flash file system? :confused:

A big thanks to Fanoush and others who have helped keep the 770 alive.
Paul

Re: running OS off mmc card - why ext2 filing system?
 

SD/MMC cards are not accessed as a raw flash device. There may still be advantages to JFFS2, but it isn't truly needed the way it is on a raw flash device.

Re: running OS off mmc card - why ext2 filing system?
 

ah, I see, with a memory card you can expect its on-board flash controller to do the wear spreading and management of blocks within erasable segments, but on the tablet itself you have to do it all yourself and if you didn't you'd probably kill the internal flash quite quickly!

Re: running OS off mmc card - why ext2 filing system?
 

No, there's no advantage to jffs2 for non-raw flash devices. Actually, there's the potential to do damage to the card as the jffs2 wear-level algorithm and the card's internal wear-leveling have the potential to cancel each other out.

Besides, have you guys investigated how jffs2 works? The wikipedia article provides a bit of information but, suffice to say, scanning a 1GB (let alone an 8GB) jffs2 filesystem into memory will take a very long time.

Re: running OS off mmc card - why ext2 filing system?
 

I'm using ext3 on mine. I do enough crazy stuff to get reboots now and then, and I'm not interested in corrupted file systems. With the price of flash cards, even if we wear them out, we can buy bigger and cheaper ones.