How to use memory allocated by dma_alloc_coherent() in cuda

Autonomous Machines Jetson & Embedded Systems Jetson TX2
#1

I am developing a pcie driver in Jetson Tx2.
I want to use DMA memory allocated by dma_alloc_coherent() in cuda.

https://forums.developer.nvidia.com/t/how-to-access-dma-alloc-coherent-memory-from-cuda/79377

https://forums.developer.nvidia.com/t/can-memory-allocated-by-dma-alloc-coherent-be-accessed-by-cuda-gpu-on-tx1/74332

I checked these two posts, but couldn’t find the answer.

Is there a way to directly use DMA memory allocated by dma_alloc_coherent() without using cudaMemcpy in CUDA?

#3

Hi,

There is a nvidia_p2p_get_pages API but it is only available for Xavier device:
https://docs.nvidia.com/cuda/gpudirect-rdma/index.html#porting-to-jetson

Thanks.

#4

I do not have jetson xavier.
Is there any possible way in jetson tx2?

#5

Hi,

Sorry that this function is only available for Xavier device.

Thanks.

#7

Hi AastaLLL, please can you help me

I have a Xavier AGX (with C5 configured in PCIe EndPoint mode) connected to an x86 host (Root-Complex). How can I use

int nvidia_p2p_get_pages(u64 virtual_address, u64 length, struct nvidia_p2p_page_table **page_table, void (*free_callback)(void *data), void *data);

on the Xavier in order to access (in my CUDA kernel) the virtual address returned by "dma_alloc_coherent() "? The first parameter of “nvidia_p2p_get_pages” can be the pointer returned by "dma_alloc_coherent() "?

Note: I use dma_alloc_coherent() in the “pci_epf_nv_test” driver to allocate 512M

Thanks

#8

Hi RokiaDiarr,

Please help to open a new topic for your issue. Thanks

#9