Re: Apparent kernel bug with GDB on ppc405

Josh Boyer
2007-10-26T20:41:36Z

On Fri, 26 Oct 2007 11:51:22 +1000
Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:

>
> On Wed, 2007-10-24 at 18:41 -0400, Daniel Jacobowitz wrote:
> > On Wed, Oct 24, 2007 at 05:32:50PM -0500, Matt Mackall wrote:
> > > Not completely implausible, but a) why isn't this seen on basically
> > > every machine with software TLB? b) why does -local- GDB, which is
> > > presumably doing much less work than gdbserver + network stack, not fail?
> >
> > You said it yourself. Local gdb does more work -> blows through more
> > TLB entries.
> >
> > I can't answer you about the other half, but I'm pretty sure TLB
> > invalidation is already supposed to be happening... somewhere.
>
> Yes. do_wp_page() -> ptep_clear_flush() -> flush_tlb_page()

Aren't there cases in do_wp_page that don't call ptep_clear_flush?
Seems anonymous pages, and possibly shared writeable pages skip that
step if reuse is true.

josh