testing current target (in gdb code)

testing current target (in gdb code)

[Miles Bader]

Hi,

I'm currently working on making gdb's v850 support work on real CPUs,
and unfortunately I can't get the hardware single-stepping to work
consistently (the hardware has lots of weird restrictions, and by doing
lots of tricks I can get it to work on some processors, but not others).

So I'd like to use GDB's software-single-stepping facility for those
cases where I can't use hardware (thanks to Kevin Buettner who told me
where to find it!); however, I'd still like to use hardware
single-stepping when possible as it seems likely to always be reliable
in some corner case or another, no matter how careful I am.  In
particular, `hardware' single-stepping works great in GDB's simulator.

I guess I can do this sort of thing by defining SOFTWARE_SINGLE_STEP_P
to call a function that looks at the current target and returns an
appropriate boolean for it (defaulting to 1 I suppose).

However I'm not sure how to test the current target; any pointers?

Or am I on the wrong track entirely, and there's a better way to do
what I want?

Thanks for any tips,

-Miles
-- 
`Life is a boundless sea of bitterness'

Re: testing current target (in gdb code)

[Andrew Cagney]

> Hi,
> 
> I'm currently working on making gdb's v850 support work on real CPUs,
> and unfortunately I can't get the hardware single-stepping to work
> consistently (the hardware has lots of weird restrictions, and by doing
> lots of tricks I can get it to work on some processors, but not others).
> 
> So I'd like to use GDB's software-single-stepping facility for those
> cases where I can't use hardware (thanks to Kevin Buettner who told me
> where to find it!); however, I'd still like to use hardware
> single-stepping when possible as it seems likely to always be reliable
> in some corner case or another, no matter how careful I am.  In
> particular, `hardware' single-stepping works great in GDB's simulator.
> 
> I guess I can do this sort of thing by defining SOFTWARE_SINGLE_STEP_P
> to call a function that looks at the current target and returns an
> appropriate boolean for it (defaulting to 1 I suppose).

See: SOFTWARE_SINGLE_STEP is backwards/sideways
http://sources.redhat.com/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gdb&pr=274&return_url=http%3A%2F%2Fsources.redhat.com%2Fcgi-bin%2Fgnatsweb.pl%3Fdatabase%3Dgdb%26cmd%3Dsubmit%2520query%26category%3Dall%26severity%3Dall%26priority%3Dall%26responsible%3Dall%26submitter_id%3Dall%26state%3Dall%26ignoreclosed%3DIgnore%2520Closed%26class%3Dall%26synopsis%3Dsoftware%26multitext%3D%26columns%3Dcategory%26columns%3Dstate%26columns%3Dclass%26columns%3Dpriority%26columns%3Dresponsible%26columns%3Doriginator%26columns%3Dsynopsis%26displaydate%3DDisplay%2520Current%2520Date%26sortby%3DResponsible%26.cgifields%3Doriginatedbyme%26.cgifields%3Ddisplaydate%26.cgifields%3Dcolumns%26.cgifields%3Dignoreclosed

I also think this came up (again) recently, perhaphs search for 
SOFTWARE_SINGLE_STEP in the mail archives.

Andrew

Re: testing current target (in gdb code)

[Miles Bader]

Andrew Cagney <ac131313@redhat.com> writes:
> > So I'd like to use GDB's software-single-stepping facility for those
> > cases where I can't use hardware (thanks to Kevin Buettner who told me
> > where to find it!); however, I'd still like to use hardware
> > single-stepping when possible as it seems likely to always be reliable
> > in some corner case or another, no matter how careful I am.
>
> See: SOFTWARE_SINGLE_STEP is backwards/sideways

That's interesting, and it's good to see that the gdb maintainers are
thinking about it (the suggested change sounds great to me), but is
such a change likely to happen any time soon?

If not, I guess I've got to play by the old cranky rules...

Anyway, it looks like there's some relevant discussion in the ML
archives so hopefully I can find some tips there (yeah I know I ought to
do that _before_ posting my question... :-)

Thanks,

-Miles
-- 
Next to fried food, the South has suffered most from oratory.
  			-- Walter Hines Page