Re: port-amd64/38969: ddb backtrace on amd64 doesn't show function arguments

[Simon Burge <simonb%NetBSD.org@localhost>]

David Laight wrote:

>  On Tue, Jun 17, 2008 at 06:25:00AM +0000, Simon Burge wrote:
>  > >Number:         38969
>  > >Category:       port-amd64
>  > >Synopsis:       ddb backtrace on amd64 doesn't show function arguments
>  > 
>  > >Fix:
>  >    Not sure.  Just changing amd64/md64/db_trace.c:db_numargs()
>  >    to return "6" instead of "0" didn't look to provide realistic
>  >    function args at a glance - I think this is similar to
>  >    sparc/mips/<other-register-args-archs> do?  Maybe tempt the
>  >    compiler somehow to save function arguments on the stack?
>  
>  The problem is that the first 6? arguments are passed in registers
>  so are very hard to locate.

That's what I meant by "tempt the compiler ...".  Sure it'd be a
performance hit, but if there was some flag to say "save every arg on
the stack on each function entry" that'd make backtraces much more
useful.

Cheers,
Simon.