Re: [RFC] I/O MCA recovery

David Mosberger
2004-05-04T18:20:11Z

>>>>> On Tue, 4 May 2004 11:07:41 -0700, Jesse Barnes <jbarnes@engr.sgi.com> said:

Jesse> On Tuesday, May 4, 2004 10:43 am, David Mosberger wrote:
>> Eh, I/O space is required to soft-fail, isn't it?

Jesse> I thought so too, but I haven't been able to find the spec
Jesse> that contains that requirement.

It's certainly implied.

>> Why can't you hide this in the platform-specific inX/outX routines? I
>> suppose it would be very slow to drain MCAs after every inX/outX, but
>> you'd have to do the slow part only once, until you know whether or
>> not the given I/O address is safe.

Jesse> This is I/O initiated by userspace loads/stores, so unless I
Jesse> wrap every in/out with some sort of ioctl or something, those
Jesse> won't help me.

User-level accesses are mapped via the MMU so you could always
intercept the page-faults.

Jesse> Also, with this scheme, we could potentially recover from
Jesse> regular read/writes too.

_If_ there is an infrastructure what you can hook into, fine. But I'm
highly suspicious of using broken platforms as a justification for new
infrastructure.

--david