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List:       uclinux-dev
Subject:    Re: [uClinux-dev] how to mount flash via jffs2 as dir /mnt ?
From:       David McCullough <david_mccullough () au ! securecomputing ! com>
Date:       2006-03-21 12:44:08
Message-ID: 20060321124408.GA12668 () beast
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Jivin Falk Brettschneider lays it down ...
> > --- Urspr?ngliche Nachricht ---
> > Von: David McCullough <david_mccullough@au.securecomputing.com>
> ...
> > Well, I committed it,  but it came in with the import of linux-2.4.21.
> > 
> > The commit log probably says something about the import of 2.4.21.
> > 
> > The comment in the code explains it IMO:
> > 
> >         /* In cfi_amdstd_write() we frob the protection stuff
> >           without paying any attention to the state machine.
> >           This upsets in-progress erases. So we turn this flag
> >           off for now till the code gets fixed. */
> I read it but wonder what it means. How can an erase be in-progress during a
> write? Does it mean two accesses from different threads? Having it
> single-threaded, AFAIK one can poll a status bit for the completion of a
> flash action, am I really right (?)...

Ok,  I could easily be wrong on this,  but it looks like the code is
unlocking the chip directly in the code instead of using the standard
MTD mechanisms for it.

And yes,  you can have processes writing to flash while others are
reading from it.  MTD deals with all this quite well via it's locking
mechanisms,  thus by passing it in any way would be bad,

Cheers,
Davidm

-- 
David McCullough, david_mccullough@au.securecomputing.com, Ph:+61 734352815
Secure Computing - SnapGear  http://www.uCdot.org http://www.cyberguard.com
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