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Re: ARM 920t queries with eCos


> Hi Mohanlal,
>
> I have not looked at all the emails that were exchanged on this. Just a
thought.
>
> So, you believe at 0x0000.0000 there is ROM physical present, but the ecos
linker scripts say that it has RAM. Is that what is not clear to you? <if
not, don't read beyond this>
Yes, you understood my problem correctly.

> If so, ARM920T has a MMU & the map presented by ecos linker scripts is the
one after the MMU is turned on. And in most of the ARM ports, the MMU table
remaps the RAM to 0x0000.0000 & Flash ROM elsewhere.
I have drawn following conclustion from above statement. Let me know if I am
wrong.
"When system is booting MMU is off and bootROM is mapped at address 0.
Therefore bootMonitor (the boot loader) gets executed. After systems boots,
MMU is turned on and a remapping happens. During remapping, RAM is mapped to
address 0 and bootROM maps to somewhere else (I suppose this should be EBI
reason. Actully it is already there, at boot time this is aliased to
bottom). The address I see in target.ld reflact address after remapping has
taken place (MMU on)."
Please send your comments on this conclusion.
>
> Hope this helps!
> -Mike.
>
>
> >From: "mohanlal jangir" <mohanlaljangir@hotmail.com>
> >To: "mailing-list ecos" <ecos-discuss@sources.redhat.com>
> >Subject: Re: [ECOS] ARM 920t queries with eCos
> >Date: Fri, 18 Jul 2003 11:19:42 +0530
> >
> > > > 4. My arm integrator manual tells following memory map
> > > > REMAP       S1[1]            map to
> > > >     0                 0                bootROM
> > > >     0                 1                flash
> > > >     1                 x                SSRAM
> > >
> > > You don't say what S1[1] is in this context.
> > >
> >S1 is 4-pole DIP switch that controls memory mapping. S1[1] is first of
the
> >four. Since on reset REMAP is "0" and S1[1] is also "0", bootROM is
mapped
> >to address 0 and bootMonitors is getting executed. But following lines
say
> >that RAM starts at address 0. This is confusing me.
> > > > MEMORY
> > > > {
> > > >     ram : ORIGIN = 0, LENGTH = 0x01000000
> > > > }
> >
> >



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