[ECOS] Re: RAM vs. ROMRAM question

Nick Garnett nickg@ecoscentric.com
Mon Oct 30 16:16:00 GMT 2006


Grant Edwards <grante@visi.com> writes:

> In gmane.os.ecos.general, you wrote:
> >  Grant Edwards <grante@visi.com> writes:
> >
> >> On 2006-10-30, Nick Garnett <nickg@ecoscentric.com> wrote:
> >> 
> >> > Using a RAM RedBoot to load RAM applications will not work
> >> > since RedBoot would load at exactly the same address as the
> >> > applications, with obvious bad consequences.
> >> 
> >> That's odd, I do it all the time. ;) I've been shipping
> >> products for years where RedBoot runs from RAM as a "ROM
> >> Monitor" and loads applications into RAM.  All you have to do
> >> is run RedBoot in a section of RAM that you don't use for
> >> applications.
> >
> > Sure. But you have to build RedBoot differently from normal RAM
> > applications in that case. 
> 
> Right.  My HAL has separate .ldi files for RedBoot.

That's not the usual pattern, RedBoot usually uses exactly the same
.ldi files as applications built for the same startup type. RedBoot
is, after all, just a particular instance of an eCos application.


> >
> > Both of which are what ROMRAM startup is designed to do.
> 
> Except then ecosconfig won't let you configure RedBoot as a
> monitor without complaining.  Which was my initial point:
> there's nothing that says a monitor can't run in RAM, so why
> does ecosconfig object to that?

What is the exact complaint you are getting?

I suspect that the problem is just the way that the platform HAL you
are using is configured. You may need to add RAM startup to the
requires statement in the definition of CYGSEM_HAL_ROM_MONITOR. There
is certainly no other reason for this not to work, we configure RAM
RedBoots all the time.

The default tends to be for RAM RedBoot to have CYGSEM_HAL_ROM_MONITOR
disabled, since it is normally used only to program new versions of
RedBoot into the flash. However, this option does not seem to have
very much effect on how RedBoot gets built; it should probably have
more.


-- 
Nick Garnett                                     eCos Kernel Architect
http://www.ecoscentric.com                The eCos and RedBoot experts


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