Re: [ECOS] Questions about GDB Ctrl-C support.

[Jonathan Larmour <jlarmour at redhat dot com>]

Grant Edwards wrote:
> 
> On Tue, Sep 11, 2001 at 05:14:05PM +0200, Jesper Skov wrote:
> 
> > >>  Well, the stub uses the debug channel and hence the driver RedBoot
> > >> provided for driving that channel. however, the stub code
> > >> internally uses VV (IIRC) so you should be able to CLAIM_COMMS in
> > >> the application (i.e., the application provides the drivers used by
> > >> printf) and still be able to use the GDB support (which will then
> > >> call into RAM for printing).
> 
> Is CLAIM_COMMS a macro?

A CDL option.

>  My snapshot doesn't have it anywhere.
> It also doesn't have *_INHERIT_CONSOLE or *_DIAG_TO_DEBUG_CHAN.
> Now that I'm overhauling my HAL, I guess I should update to a
> newer snapshot (something I haven't been looking forward to).

If you're wondering about these types of things and just want to have a
quick look at the current CVS repo, you could try CVSweb:
http://sources.redhat.com/cgi-bin/cvsweb.cgi/?cvsroot=ecos

> > Grant> I'm not sure what you mean by "call into RAM".  Do you mean
> > Grant> that the GDB stubs in RedBoot will use routines in the eCos
> > Grant> application (via the VV table) to do I/O to/from GDB?  [In my
> > Grant> case both RedBoot and the eCos application are in RAM.]
> >
> > Indeed. The VV table allows calling from RAM to ROM or vice
> > versa. Effectively removing the need for callee and caller to be in
> > the same (linker) address space.
> 
> When the eCos app takes over the comm channels, is there any
> state info that gets lost? 

No.

> Where is the identity of the diag
> channel (1) stored?

A pointer to the current diag channel is stored in the virtual vector
table. But if claiming comms (or not inheriting console) then that will be
overridden to use the default channel. There's no concept anywhere of
trying to preserve the channel number, but using a separate instantiation
of the channel functions (i.e. functions in your program, rather than
RedBoot).

Jifl
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