[openib-general] Question on : ib_reg_phys_mr()

[James Lentini]

On Sat, 8 Apr 2006, Devesh Sharma wrote:

> In your nfs-rdma context what this function is supposed to do?

It should create a memory region for the specified address range. For 
the exact semantics, see the IBTA spec's description of the REGISTER 
PHYSICAL MEMORY REGION verb (section 11.2.8.3 of the 1.2 spec).

> I know that this function returns memory region, but what is the 
> difference from other mr returning functions? why get_dma_mr can't 
> be used?

get_dma_mr() will return a memory region which covers all of physical 
memory. For security reasons, it is not always desirable to expose all 
of physical memory. ib_reg_phys_mr() allows for more fine grained 
access control.