[openib-general] High memory

[Grant Grundler]

On Thu, Nov 17, 2005 at 12:33:22AM -0500, Shuang Liang wrote:
> Hi,
>   I am new here with some problem of gen2 programming, hope somebody 
> can help me. I was trying to send a message from a kernel buffer to a 
> remote userland program on IA-32 machines.
>   Basically, what happened was I used get_dma_mr to get memory 
> registered. And I noticed if a buffer is allocated from high memory 
> (address >f8000000), then the data can not be delivered correctly to the 
> receiver side(both send recv completes successfully, but with wrong 
> data). I thought the problem could have been that I used virt_to_phys 
> for address translation.

Using "virt_to_phys" is always wrong when trying to get a DMA mapping.

> But I can't find any appropriate ones for high 
> memory address translation. I wondering if somebody could give me some  
> suggestions on this.

I don't know enough context.
Are you trying to write an openib kernel driver?
If so you want to read "Documentation/DMA-API.txt" for hints on the
available DMA mapping interfaces and then look at how SDP or IPoIB
use the described DMA interfaces.

hth,
grant