Re: RELEASE BLOCKER: Linux doesn't follow x86/x86-64 ABI wrt direction flag

Joe Buck
2008-03-05T22:13:08Z

On Wed, Mar 05, 2008 at 10:43:33PM +0100, Michael Matz wrote:
> Hi,
>
> On Wed, 5 Mar 2008, Joe Buck wrote:
>
> >
> >
> > On Wed, 5 Mar 2008, Jan Hubicka wrote:
> > > > Linux kernel is disabling red zone and use kernel code model, yet the
> > > > ABI is not going to be adjusted for that.
> > > >
> > > > This is resonably easy to fix on kernel side in signal handling, or by
> > > > removing std usage completely
> >
> > On Wed, Mar 05, 2008 at 10:02:07PM +0100, Michael Matz wrote:
> > > That is true. But it requires updating the kernel to a fixed one if you
> > > want to run your programs compiled by 4.3 :-/ Not something we'd like to
> > > demand.
> >
> > I changed the title just for emphasis.
> >
> > I think that we can't ship 4.3.0 if signal handlers on x86/x86_64
> > platforms for both Linux and BSD systems will mysteriously (to the users)
> > fail, and it doesn't matter whose fault it is.
>
> FWIW I don't think it's a release blocker for 4.3.0. The error is arcane
> and happens seldomly if at all. And only on unfixed kernels. A program
> needs to do std explicitely, which most don't do _and_ get hit by a signal
> while begin in a std region. This happens so seldom that it didn't occur
> in building the next openSuSE 11.0, and it continually builds packages
> with 4.3 since months.
>
> It should be worked around in 4.3.1 if at all.

OK, I suppose that I over-reacted, and it seems that the ship has sailed
in any case.

I agree that it's obscure, and I think that the only reason to worry is
if it introduces a means of attack, which seems unlikely.