[Openib-windows] [PATCH] HCA: Allocate MDLs for memory registrationmanually - complete message

Fab Tillier ftillier at silverstorm.com
Fri Oct 7 13:08:40 PDT 2005


> -----Original Message-----
> From: Jan Bottorff [mailto:jbottorff at xsigo.com]
> Sent: Friday, October 07, 2005 12:57 PM
> The buffer size limitation that can be described by an MDL is because
> the size field in the MDL structure is only 16-bits (on 32-bit Windows).
> The calculation shown in the DDK docs for IoAllocateMdl is based on this
> 16-bit field.
> I don't see how allocating some non-paged pool and then calling
> MmInitializeMdl helps, the size field in the MDL structure is still the
> same size. MmInitializeMdl has exactly the same limits as IoAllocateMdl,
> although the DDK docs don't mention this.

I had missed that, thanks.  Consider this patch moot.  Note that the
registration calls should probably be updated to split large registrations into
multiple MDLs so that buffers larger than 32MB (on 64-bit machines) and larger
than 64MB (on 32-bit machines) can be registered.

Thanks for the feedback!

- Fab

More information about the ofw mailing list