Re: [openrisc] need help with boot strategy

[Patrick Pelgrims <patrick.pelgrims@pandora.be>]

Title:

Marko Mlinar wrote:
> > 3) Make a hardware bootstrapper which can hold the CPU in reset, load the
> > CPU RAM from an external source and release the reset line.
> >
> > This may at least get you thinking on what is appropriate for your
> > platform.
> >   
> It goes the same as for all other platforms.
>
> I use gdb to load an application into RAM, or load the application into flash, 
> which then copies .data to RAM and executes itself from RAM/flash.
> See linker (.ld) scripts in e.g. or1ksim/testbench for latter loaders. First 
> one is trivial anyway.
At the end, in an embedded application there is no gdb :-).
So option 3 would be nice, if more than one 'external' option could be provided
by e.g. jumper settings or flash settings.
1) Downloading via the serial port (a lot of processors have this option:
Leon, MC68VZ328 ...AVR..).
     The first firmware or bootcode could be loaded internal/external and
on board flash could be programmed.
     JTAG can also be used, but commercial JTAG-tools and software are expensive
2) Starting from internal/external (flash) memory.
     This mode could be used to start up the application (for consumer use).
3) Booting from an other external device (ethernet, compact flash, memory
stick ...)
     
These methods only need an extra state-machine ;-)

Greatings,

Patrick Pelgrims
> best regards,
> Marko
>
>
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