Re: gdbarch_init, ABI, and registers

[Tim Newsome <tim@sifive.com>]

On Fri, Dec 8, 2017 at 4:20 AM, Ulrich Weigand <uweigand@de.ibm.com> wrote:

> No, this doesn't look correct to me.  Note that it is normal during
> GDB operation that several different gdbarch objects are in use,
> which have somewhat different contents and are used for different
> purposes.
>

Ah! This is super helpful, and what I was missing. I'm adding it as a
comment to `struct gdbarch`.

Am I right in that riscv_gdbarch_init() can differentiate these two cases
based on whether a target description is passed in or not? Eg. if there is
a target description, register structures need to be set up, and if there
isn't then that's not necessary?

I guess I still haven't quite understood why exactly any of this
> is causing a problem for you.  Yes, gdbarch objects returned from
> gdbarch_from_bfd will not have correct register info.  But those
> objects also should never be used in any context where registers
> matter.  Can you be more specific what the actual problem you're
> seeing is?
>

The problem I was seeing is that registers were showing up which shouldn't.
The reason (as I understand it now) is that I was depending on global
variables in riscv-tdep.c instead of putting them in gdbarch.data. I'll
make that change, and hopefully then everything will be better.

Thank you,
Tim