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Re: [rfc] MSR and System regs for RedBoot target
- From: Andrew Cagney <ac131313 at ges dot redhat dot com>
- To: Mark Kettenis <kettenis at chello dot nl>
- Cc: gdb-patches at sources dot redhat dot com
- Date: Thu, 19 Sep 2002 19:24:41 -0400
- Subject: Re: [rfc] MSR and System regs for RedBoot target
- References: <3D6D9B48.70407@ges.redhat.com> <86hehdp9dn.fsf@elgar.kettenis.dyndns.org>
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'll park this in my sysregs branch. RedBoot is available at
http://sources.redhat.com/redboot/
comments?
Is there consensus yet on how we should create the types for those
flag bits? If we choose Michael Ludvigs approach, this code should be
converted before we check it in.
Yes, this stuff will need to be updated.
(I need to make those registers lowercase as well).
Andrew