Re: [PATCH]IB/ehca:reject dynamic memory add/remove

On Tue, 2008-10-14 at 14:23 +0200, Stefan Roscher wrote:

On Monday 13 October 2008 07:09:26 pm Dave Hansen wrote:

quoted

On Mon, 2008-10-13 at 13:10 +0200, Stefan Roscher wrote:

quoted

Since the ehca device driver does not support dynamic memory add and remove
operations, the driver must explicitly reject such requests in order to prevent
unpredictable behaviors related to memory regions already occupied and being
used by InfiniBand applications.
The solution is to add a memory notifier to the ehca device driver and if a request
for dynamic memory add or remove comes in, ehca will always reject it.

Why doesn't the driver support it?

This seems like an awfully extreme action to take.  Do you have plans to
support this in the driver soon?

There is currently a slight incompatibility how openfabrics uses MRs
and how System p does DMEM add/remove, which basically disables this
support.
If you want to talk to the firmware developpers, I can give you the right contacts.

I wish I knew what an 'MR' is. :(

Could you be a bit more specific so we can get a better changelog?
Perhaps if we understand the situation better, we can come up with a
better solution.

Does this have anything in common with the problems with 16GB pages?

-- Dave