Pass gdbarch, not regset, to supply regset et.al.?
Andrew Cagney
cagney@gnu.org
Wed Nov 19 23:28:00 GMT 2003
> Date: Wed, 19 Nov 2003 14:37:58 -0500
> From: Andrew Cagney <ac131313@redhat.com>
>
> Mark,
>
> I'm wondering if it would be easier to explicitly pass the gdbarch
> instead of the regset to the regset function?
>
> I've thought about that, but I don't think so. I'd like to use these
> register sets even for cases where there's no gdbarch that we can
> easily get at. I'm thinking specifically about the *-nat.c modules
> where register sets are provided by ptrace(2), /proc, etc.
Sorry, I'm lost. ptrace and /proc both have an implied architecture, or
at least OS.
> At present the lookup regset code does this:
>
> tdep->gregset = XMALLOC (struct regset);
> tdep->gregset->descr = tdep;
> tdep->gregset->supply_regset = i386_supply_gregset;
>
> so that the architecture is tunneled through to the regset function.
>
> const struct gdbarch_tdep *tdep = regset->descr;
> ...
> for (i = 0; i < tdep->gregset_num_regs; i++)
>
> I'm wondering if it would be easier to just pass the architecture?
>
> Well, you can always pass gdbarch as the description. The point is
> that the current implementation makes it possible to pass in something
> that isn't related to a gdbarch at all. I also think it doesn't
> necessarily make sense to copy the i386 implementation. For SPARC I'm
> already thinking about a somewhat different implementation.
Will anyone every actually do this, or have we ended up with too much
generality?
> At the same time, I'm wondering if i386_regset_from_core_section should
> be abstracted a little so that, like reggroups it was set up:
>
> set_regset_supply_core_section (arch, ".reg", size, i386_supply_regset);
> set_regset_supply_core_section (arch, ".reg2", i386_supply_fpregset);
>
> Hey, since when is GDB is written in C++ ;-).
shhhh
> ...
> f = regset_supply_from_core_section (core_arch, ".name", length);
> f (core_arch, current_regcache, regnum, contents, length);
> ... or even the short cut ...
> regset_supply_core_section (core_arch, ".name", current_regcache,
> regnum, contents, length);
>
> Thoughts?
>
> Well, your set_regset_supply_core_section proposal makes it a bit
> awkward to override a particular core section defenition for a
> specific target. Suppose that I have a generic i386 implementation
> for say ".reg" sections which I want to override for GNU/Hurd?
set_regset_core_section (arch, ".reg", size, i386_collect_gregset)
... then later ...
set_regset_core_section (arch, ".reg", size, gnuhurd_collect_gregset)?
> I just came across this bit of PPC64 GNU/Linux code
>
> > void
> > ppc_linux_supply_gregset (char *buf)
> > {
> > int regi;
> > struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
> >
> > for (regi = 0; regi < 32; regi++)
> > supply_register (regi, buf + 4 * regi);
>
> (yes, that's a "4" not "8") and was studying the new mechanism.
>
> It might pay to study the other PPC and PPC64 OS'es to see whether
> they could share an implementation.
True.
Andrew
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