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RE: J3 flash lockbits across reset
- From: Gary Thomas <gary at mlbassoc dot com>
- To: Stephen Goadhouse <stephen dot goadhouse at adiengineering dot com>
- Cc: 'Andrew Lunn' <andrew at lunn dot ch>, 'alfred hitch' <alfred dot hitch at gmail dot com>, eCos Discussion <ecos-discuss at ecos dot sourceware dot org>
- Date: Thu, 12 Jan 2006 06:46:16 -0700
- Subject: RE: [ECOS] J3 flash lockbits across reset
- References: <auto-000083259218@mail.suremessenger.com>
On Thu, 2006-01-12 at 08:40 -0500, Stephen Goadhouse wrote:
> > -----Original Message-----
> > From: ecos-discuss-owner@ecos.sourceware.org
> > [mailto:ecos-discuss-owner@ecos.sourceware.org] On Behalf Of
> > Gary Thomas
> > Sent: Thursday, January 12, 2006 8:22 AM
> > To: Andrew Lunn
> > Cc: alfred hitch; eCos Discussion
> > Subject: Re: [ECOS] J3 flash lockbits across reset
> >
> > On Thu, 2006-01-12 at 09:44 +0100, Andrew Lunn wrote:
> > > On Thu, Jan 12, 2006 at 03:33:03AM -0500, alfred hitch wrote:
> > > > Hi,
> > > >
> > > > I am confused on what is the correct behavior across power resets
> > > > (of hardware) for J3 flash'es.
> > > >
> > > > 1) Will all sectors which were locked before power reset,
> > remain so ?
> > > >
> > > > I am confused by some posts on net, saying they get
> > locked (all) by
> > > > default across resets (irr. of before power reset status)
> > > >
> > > > Some say, it is unlocked (all blocks )by default across resets.
> > > >
> > > > I dont think flash should change status across resets. It should
> > > > preserve whatever I locked before reboot and vice versa.
> > >
> > > The data sheet for the chip is the best source of answer for this
> > > question.
> > >
> >
> > The J3 devices are different from most other FLASH devices -
> > all sectors are *always* locked after a device reset. This
> > is just how the hardware works.
>
> This is incorrect. You must be thinking of the new Intel P30 Flash. For
> the old reliable J3 Flash, the lock bits are stored in non-volatile Flash
> cells and survive a reset/power cycle. If you lock a sector in J3 Flash,
> it stays locked, through resets and power cycles, until the "unlock all
> sectors" command is given.
>
> The new Intel P30 Flash is like you describe. The lock bits are stored
> in volatile memory. All sectors are in the lock state whenever you reset
> the chip or power cycle. Any sectors that you unlocked will not be
> remembered through resets/power cycles. You have to always unlock
> sectors before writing to them. It's a super pain! Apparently some
> older Intel Flash series also did this and for some reason they brought
> back this stupid feature. It totally goes against what RedBoot expects
> from Flash.
Sorry, you are correct (I recently did some work with the P30 FLASH
devices and they were fresh in my mind, just not the moniker)
--
------------------------------------------------------------
Gary Thomas | Consulting for the
MLB Associates | Embedded world
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