RE: [Linux-ia64] [PATCH] MCA recovery for TLB faults for 2.4

>>>>> On Mon, 2 Jun 2003 10:00:28 -0700, "Luck, Tony" <tony.luck@intel.com> said:

  Tony> At the moment the trust level is extremely high.  Linux
  Tony> doesn't even provide a checksum for the ia64_os_mca_dispatch
  Tony> entry code when it registers it with the SAL.

That's true.

  Tony> A checksum in the list of saved translations would only be
  Tony> part of reducing the level of trust ... we'd also need to
  Tony> validate that the entire code path has the correct code (not
  Tony> just the entry point).  There are several other data items on
  Tony> which the code also relies which a truly paranoid MCA handler
  Tony> would also need to validate.

I probably just don't understand what the plan is here.  Are you
planning to fix everything in one fell swoop?  If not, I think
incrementally improving the situation makes sense (i.e., if you work
on piece X, make X as solid as possible; over time do this for more
and more pieces of the MCA subsystem).  There is no doubt that making
the entire MCA subsystem as robust as possible involves a huge amount
of rather tricky work.  Same goes for the INIT path, of course (there
are obvious ways to deadlock it right now; probably something that
could benefit from a reasonably generic lock-busting infrastructure).

	--david