Re: [rfc] MSR and System regs for RedBoot target

[Daniel Jacobowitz <drow@mvista.com>]

On Thu, Sep 19, 2002 at 07:24:41PM -0400, Andrew Cagney wrote:
> >Andrew Cagney <ac131313@ges.redhat.com> writes:
> >
> >
> >>Hello,
> >>
> >>The attached (a patch against my sysregs branch) based mostly by code 
> >>previously written by Fernando Nasser, adds MSR and system register 
> >>support for an i386 RedBoot target.  They each get their own group. 
> >>That way:
> >>	info registers msr
> >>and 
> >>info registers system
> >>works (but MSR and SYSTEM registers are not displayed by ``info 
> >>registers''.).
> >
> >
> >Those system registers seem like a good idea to me.  I'm not so sure
> >about those MSRs.
> 
> I don't know either here.  I'm going through old lost changes.
> 
> >>The patch (apart from demonstrating that reggroups really do work :-) 
> >>identifies a number of issues:
> >>
> >>- The patch makes RedBoot the default i386 abi -- if nothing else hits, 
> >>this gets to be it.  Its done by brute force.  This goes back to the 
> >>default discussed earlier for the ``set osabi'' command.  Better re-read 
> >>the thread ...
> >
> >
> >Does the OS/ABI have to be named "RedBoot"?  I think most of this
> >stuff could just as well be added to the generic i386 target.
> 
> It depends.
> 
> The MSR registers are implemented in a RedBoot specific way - it uses 
> target_query() and a qMSR packet.  The qMSR packet came about because 
> there are potentially ~4gb of MSR registers and the remote protocol 
> doesn't support sparse register numbers.
> 
> There are several possible paths here:
> - leave qMSR as something RedBoot specific
> - formalize it and make it part of the protocol
> - provide a mechanism for handling sparse remote protocol register 
> numbers so that [Pp] packets can be used.

I'm all for that last one... but it's tied in with all the
defining-remote-register-mapping discussions that never seem to get
implemented.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer