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Re: [patch]: Replace stryoul call to fetch address
On Feb 27 19:14, Pedro Alves wrote:
> On 02/27/2013 06:38 PM, Corinna Vinschen wrote:
>
> >> IIRC, the matching Cygwin code that that special
> >> Cygwin signals handling was never implemented, or it was disabled
> >> on Cygwin, or some such, and that gdb bits is actually causing
> >> trouble -- see http://sourceware.org/ml/gdb-patches/2013-02/msg00122.html.
> >> We should just zap it all.
> >
> > I don't know exactly. Probably cgf would be able to answer this
> > better than me.
>
> I think I recall some email from him long about about the
> cygwin side of that, but he wasn't against removing these
> bits of on the gdb end in that url above, so...
Chris, ping?
> > In fact I have a SEGV right now which I still have
> > to investigate, but I'm working on GDB only as a side job.
>
> Sure. I just meant to point out that that's exactly the code
> you're touching. ;-)
The SEGV occurs in exception.c, function throw_exception, though.
The `*current_catcher->exception = exception;' assignment crashes
because current_catcher->exception is NULL. I don't understand yet
why it's NULL, and why the throw_exception function doesn't test
this before trying to write *current_catcher->exception.
> >> One thing that comes to mind is I think we'll need to have separate
> >> mingw64/cygwin64 osabis. Currently, mingw 32/64 use
> >> GDB_OSABI_CYGWIN, and that limps along, but with LP vs LLP, that
> >> won't work.
> >
> > Why not? The only difference between the x86_64 Cygwin and Mingw ABI
> > is the sizeof long. And that's noted in the dwarf debug info.
>
> Not every use use of the target's "long" goes through the debug info. I
> see uses of gdbarch_long_bit and builtin_long in the expression
> machinery, for example in c-exp.y, for handling integer constants,
> or in eval.c, for type promotion. x64's long is fixed to 32-bit
> in amd64_windows_init_abi.
Oh, hmm. I didn't notice that. So, well, maybe...
> > Apart
> > from a strange crash when trying to load stripped executables, I'm
> > using a x86_64 Mingw GDB to debug x86_64 Cygwin DLL and binaries.
> > I'm not sure this single difference justifies distinct OSABIs.
>
> Sure, we'll limp along. But there are cases that bypass debug info.
> A distinct OSABI seems like the proper mechanism to me. Time
> will tell. ;-)
...you're right. I just don't know if I'm really the right person
to do that.
> [...]
> > Ok, I apply it then with only the int changed to unsigned.
>
> Thanks.
Applied.
Corinna
--
Corinna Vinschen
Cygwin Maintainer
Red Hat