[openib-general] [kDAPL]How to register a vmalloc() allocated buffer

[Grant Grundler]

On Tue, Dec 06, 2005 at 08:52:13PM +0800, Ian Jiang wrote:
> Hi James,
> You are always so kind!
> Now I have a question about reading a buffer of a application in user space.
> Is it the only way to use the uDAPL?
> I used to have an idea like this:
> The application in user space gives the virtual start address and length of
> its data buffer to a kernel module program. This kernel program acts as a
> application of the kDAPL and registers the user space data buffer with the
> kDAPl,

Ian,
If you are doing this with OpenIB, my advice is to NOT start with kDAPL.
AFAICT, kDAPL is going away once any dependencies on it are resolved.
And it's clearly not going to be pushed to kernel.org source trees.
ISTR Dan Bar Dov wrote iSER was no longer dependent on kDAPL but
not sure if that was the only module.


> then request a RDMA read operation to complete the data transferring.
> But I think it is not feasible after getting your last reply. Am I right?
> Please give some suggestion and thanks very much!

In general, a kernel module can map a user space address to
a "DMA Address". OpenIB code has interfaces to register the
"DMA Address" with the IB card.

grant