RE: [ECOS] interrupt/virtual vectors confusion

[Gary Thomas <gary at mlbassoc dot com>]

On Tue, 2005-08-16 at 15:27 +0100, Matt Sartori wrote:
> Eeek! But that would mean that Redboot can only properly work as a
> bootloader for Redboot "enabled" programs. It was my understanding (and
> basis for advocating it as a viable alternative to writing our own
> custom bootloader) that Redboot is able to run any application and only
> re-appear when the board is reset.

It absolutely *can* do what you want, but if your hardware does not 
have an easy way to redirect the VSR handling (where code jumps to when
an interrupt or exception happens), then you'll have to add some code
to your HAL to make this work cooperatively.  If that's the case, then
your application will still have to somehow indicate to RedBoot what it
wants to do when the interrupt or exception happens.  We're just talking
semantic details here - either you invent some mechanism to handle this
or you run eCos programs (which will also have to have similar 
mechanisms via the HAL).

> -----Original Message-----
> From: Gary Thomas [mailto:gary@mlbassoc.com] 
> Sent: 16 August 2005 15:18
> To: Matt Sartori
> Cc: Andrew Lunn; eCos Discussion
> Subject: RE: [ECOS] interrupt/virtual vectors confusion
> 
> On Tue, 2005-08-16 at 15:06 +0100, Matt Sartori wrote:
> > >Is Blinky an eCos RAM program? If so it should of taken over the
> > >interrupt vectors from Redboot. Redboot should no longer be active
> > >unless blinky actually calls into Redboot via the virtual vectors.
> > 
> > Blinky is just a standalone program I decided to use as a test. The
> only
> > change I've made to it to make it run is to link it directly into free
> > ram so that I can run it after having loaded it from Redboot (with a
> > load -r -m ymodem -b 0x20005b68). 
> > The reason I know that Redboot is handling (or at least that Redboot
> > code is being called) the IRQ is that I put while(1){flash an led
> every
> > second} at the top of hal_IRQ_handler and that it gets stuck there
> when
> > I run Blinky.
> 
> Then, this is just as it should be :-)  Unless you make Blinky into an
> eCos program, which uses the HAL interrupt mechanisms, RedBoot is quite
> happily going to try and handle the interrupt, etc.
> 
> -- 
> ------------------------------------------------------------
> Gary Thomas                 |  Consulting for the
> MLB Associates              |    Embedded world
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------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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