Re: [libunwind] suggest adding unw_init_local_accessors

[Mark Young]

Yes, I can accomplish what I want by copying the accessors struct belonging
to unw_local_address_space ...
    unw_accessors_t ac;
    unw_addr_space_t as;
    ac = *unw_get_accessors(unw_local_addr_space);
    ac.access_mem = my_access_mem;
    as = unw_create_addr_space(&ac);
    rc = unw_init_remote(&cursor), as, uc)

I'm concerned by the removal of the acquire_unwind_info accessor function.
The new dynamic unwind info registration scheme requires all active procedures
to be registered before unwinding begins. The list of registered dynamic
procedures duplicates a similar list necessarily maintained by our application.
I understand and appreciate how the underlying descriptor structure can be
shared by all procedures with identical prologue/epilog code sequences, but
the number of dynamic procedures can be very large (for example, when simulating
a large chip design). I think it would be worthwhile to allow the application
to manage the detailed list of dynamic procedures if it so chooses. In our
case, the dynamic procedures are generated consecutively into large allocated
blocks -- which suggests a compromise -- define some way to register a dynamic
code section with a callback function to be used during an unwind step to
obtain the procedure entry address and unwind info for any ip address that
falls in the section.
--Mark

David Mosberger wrote:
> > > > > > On Tue, 12 Nov 2002 15:42:41 -0800, Mark Young <address@hidden> said:
> > > > > >           
> > > > >         
> > > >       
> > >     
> >   
>
>   Mark> In using libunwind with dynamically generated code, it would
>   Mark> be useful to call the register/memory/unwind-info access
>   Mark> functions used by unw_init_local to handle frames created by
>   Mark> non-dynamic code. Rather than simply making the local access
>   Mark> functions externally visible, I suggest adding a new routine
>   Mark> "unw_init_local_accessors" to initialize an unw_accessors_t
>   Mark> structure in the same manner as unw_init_local. This would
>   Mark> allow personalized access functions to be selectively
>   Mark> substituted for local access functions, as in this example:
>
> This should now be possible via the unw_get_accessors() routine.
> Mark, could you let me know if this meets your needs?
>
> Thanks,
>
> 	--david

-- 
Mark Young            address@hidden     Tel: 503.526.1661
Staff Engineer         www.model.com      Fax: 503.526.5473
Model Technology, Inc.
10450 SW Nimbus Avenue/Bldg RB, Portland, OR 97223-4347 USA