Re: [uCsimm] FS on FLASH

From: Erwin Authried (
Date: Sat Feb 26 2000 - 09:15:30 EST

Hello Kwonsk,

thats GREAT news. My congratulations. I can't wait seeing your changes.

"권석근" wrote:

> Hi, all
> I'm happy to introduce Writable File System on FLASH for uClinux.
> Sometimes ago, i thought about how useful if could use FLASH memory
> just like normal hard disk. Current romfs on flash could be ok for
> most applications, but romfs has basic limitation. If i want to change
> some configuration files for my application, i must re-generate romfs with
> kernel
> and download it, and it seemed to me uneasy.
> Therefore i tryed to make writeable file system on flash about 3 months
> and got success.
> My code is based on the progress at MTD
> ( ).
> It's scheme is msdos fs on the top of FTL (Flash Translation Layer?) on the
> top of MTD device. i've reservered 512K bytes for this at the end of flash
> memory and
> made MTD driver for flash and did little hacking on msdos fs driver of
> uClinux.
> I've formatted /dev/ftla with mkdosfs and mount it /mnt. And GOT DOS disk.
> I've tested some file copy and power-off and reboot. after mount /dev/ftla
> on /mnt
> i could also SEE it. yah, It works!
> Maybe this work could be useful or just be a one of toy :-)

I hope you are joking only. There's no doubt that it`s useful, even if its not
(yet) perfect.

> But i'm now preparing my patch and you could see my code someday.
> note:
> 1, why msdos? -> After some test i realized that ext2fs did writing request
> more
> frequently even if i did not do anything (ex, file copy). this could be bad
> for
> FLASH. and msdosfs didnot try any writing if i do not try actual writing.
> maybe ext2fs need some update for it's own purpose and it's too large to
> hack for me.
> 2, for MTD on flash, kernel must be ram based. i've applied patch for ram
> based kernel
> (i could'nt memory right now where this patch comes from, but somewhere in
> this mailing list)
> even original romfs must be copyed to ramdisk. Well,, this could be a
> panalty.

I took a look at the MTD implementation some time ago, and I큟 thinking
about a FS that can be in the same flash as the kernel, possibly even with
realtime linux.A small part of the kernel must be kept in RAM, at least the
part for flash programming and interrupt handling code to make it possible
to use the erase suspend feature that is available in all (or most?) flashroms.

> Thanks
> kwonsk
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