Re: [PATCH 4/4] Don't throw an error in 'info registers' for unavailable MIPS GP registers.

["Maciej W. Rozycki" <macro@imgtec.com>]

On Tue, 18 Apr 2017, John Baldwin wrote:

> >  Minimising changes is not our goal though, unlike making them correct.  
> > And I think we need to tell apart a situation where a register (FIR) is 
> > invalid according to the OS ABI and where a subset of registers may not 
> > always be accessible.
> 
> For FreeBSD/mips in particular I will probably fix the FIR issue by fixing
> FreeBSD to export FIR.

 We'll still have to handle old kernel versions that do not have the fix.

>  That said, 'info registers' on other architectures
> is consistent in that they do not throw an error for an unavailable register
> but annotate it as such.  The goal of this patch was to align MIPS with
> other architectures in terms of that behavior.  Other architectures also
> permit registers to be unavailable without requiring a custom target
> description FWIW (e.g. the segment registers on x86 are effectively
> "optional" and not always supplied by a target).

 Agreed, however you need to be clear in your patch description which of 
the two bugs present here it is intended to fix.

> >  Thanks for checking that.  NB I find output above quite messy, especially 
> > the lack of column alignment, e.g. `r14' vs `r15'.  It makes it hard to 
> > read for me.
> 
> I don't disagree with the note on alignment.  That is probably worth fixing
> in a separate change.

 Sure, I haven't asked you or indeed anybody to rush fixing it (although 
obviously I won't mind either).

 I'll look through v2 of your changes and see if I have any further
concerns.

  Maciej