Re: Apparent kernel bug with GDB on ppc405

On Fri, 26 Oct 2007 11:51:22 +1000
Benjamin Herrenschmidt [off-list ref] wrote:

On Wed, 2007-10-24 at 18:41 -0400, Daniel Jacobowitz wrote:

quoted

On Wed, Oct 24, 2007 at 05:32:50PM -0500, Matt Mackall wrote:

quoted

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