Re: [uCsimm] FS on FLASH

From: 권석근 (kwonsk@mutech.co.kr)
Date: Sun Feb 27 2000 - 21:45:37 EST


Hi, all
I'm happy to hear comment from Erwin Authried and Stuart Hughes.
(I must be hurry for releasing my porting!). Thanks.
Yesterday at home, i thought about changing booting scheme of uClinux.
Insted of root file system on romfs(blkmem), how about root file system
on dosfs flash disk. (just more like normal desktop linux).
Then we could change rc files and network configurations with ease.
My suggestion is like this
+----------------------+
| boot loader | (64K for jeff's loader)
+----------------------+
| uClinux kernel | (about 640K for future, current image is ~500K.
| | this area need not on FS. just use binary
area
| | scheme currently used)
+----------------------+
| Root FS | (640KB first flash disk for root file system
| | having /etc, /dev, /bin, /sbin, ...)
+----------------------+
| User Disk | (700KB, or more if we have large flash,
| | second flash disk for user, having /usr,
/home ...)
+----------------------+
and of course /tmp, /var will use normal ramdisk.
(my note: FTL layer is based on and well knows flash technology
it utilizes flash with smart idea, like maximum lift time of flash. but
we always take a cuation about life time of flash. In my thought
1 full erase (700KB) a day will take flash live about more than 200 year!
100000 erase/365. (FTL layer will take care of smart erase distribution).
How about when fs crash, it could be rather cumbersom than life time of
flash.
but today, we normally use flash as a hard disk in the terms of DiskOnChip
even if it could be crash!. Well,,, this problem could be removed if we
mount flash with read only option after it contents is fixed. )

How about this idea. Request your comments.
thanks.
kwonsk

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