[ECOS] RedBoot go command enhancement

Gary D. Thomas gary.thomas@mind.be
Thu Jan 30 17:20:00 GMT 2003


On Thu, 2003-01-30 at 09:38, Mark Salter wrote:
> >>>>> Gary D Thomas writes:
> 
> > On Thu, 2003-01-30 at 09:12, Mark Salter wrote:
> >> 
> >> Here's a patch I've been playing around with. It provides a
> >> mechanism for programs started by the RedBoot go command to
> >> return to the RedBoot prompt and have its exit status displayed.
> >> It also adds a -c flag to the go command which prevents the
> >> caches from being disabled before jumping to the program. I've
> >> only tried it with standalone newlib/libgloss based apps, but
> >> eCos apps should also be able to use the VV mechanism as well.
> >> I thought I'd throw this out and solicit any comments.
> >> 
> 
> > Nice.  My only concern is that "workspace_end" is a scary place
> > to keep the saved context.  Maybe this should be in [static] low
> > memory?
> 
> Yeah, I have been waffling over that as well. The only problem
> with a static area in RedBoot's area is that there doesn't
> appear to be a good way to figure out the size requirement in
> an architecture neutral way. You need room for HAL_SavedRegisters
> plus some architecturally defined padding. For instance, you
> just need a little padding on ARM for 16byte alignment, but on
> mips there is an extra 56 bytes that is probably an ABI stack
> frame thing.
> 

Maybe we should have a HAL_THREAD_CONTEXT_SIZE macro defined
by the architecture?  It just seems unsafe that one can't know
how how much of the "stack" is used up for a saved context.

Anyway, now that I look at it closer, I don't think this
really matters because the actual saved return info is
stored on RedBoot's own stack and pointed to by "go_saved_sp".

In other words, ignore my concern.  Go ahead with it :-)

-- 
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|       Mind: Embedded Linux and eCos Development        |
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| Gary Thomas              email:  gary.thomas@mind.be   |
| Mind ( http://mind.be )  tel:    +1 (970) 229-1963     |
| gpg: http://www.chez-thomas.org/gary/gpg_key.asc       |
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