How to read/write iova(I/O Virtual Address) of PCIE endpoind mode

[Wilson_Lin]

Hi Nvidia,

I’m testing the endpoint mode of PCIE,
I add the patch of the topic.

How do I increase size of BAR0 in Endpoint Mode on Orin NX

Hi Nvidia, I’m following this topic to modify pci-epf-nv-test.c driver. https://forums.developer.nvidia.com/t/increasing-size-of-bar0-in-endpoint-mode/232498 But I have same question od this topic. https://forums.developer.nvidia.com/t/in-pcie-endpoint-and-rootpoint-modes-after-increasing-the-bar0-size-how-to-test-the-data-communication/261514 I can’t see the BAR0 RAM physical address, too. wilson@OrinNX-EP:~$ sudo dmesg | grep pci_epf_nv_test [ 522.603944] pci_epf_nv_test pci_epf_nv_test…

The patch work fine and I got the iova of EP side.
But how cauld I read/write the IOVA of PCIE.

wilson@OrinNX-EP:~$ sudo dmesg | grep pci_epf_nv_test
[  522.603944] pci_epf_nv_test pci_epf_nv_test.0: BAR0 RAM IOVA: 0xe0000000

[Wilson_Lin]

Hi ,
Could anyone help us?

[WayneWWW]

Hi Wilson,

From RP → EP, you can access it via BAR address.
sudo lspci -vvv | grep region gives BAR address, use region 0 address to access the memory allocated on EP.

[Wilson_Lin]

Hi Wayne,

Yes, I can get Region 0 address is 0x2428000000

RP:~$sudo lspci -vvv -s 0004:01:00.0 | grep Region
	Region 0: Memory at 2428000000 (32-bit, non-prefetchable) [size=64M]
	Region 2: Memory at 2140000000 (64-bit, prefetchable) [size=128K]
	Region 4: Memory at 242c000000 (64-bit, non-prefetchable) [size=4K]
RP:~$ sudo busybox devmem 0x2428000000
0x00000000

But It looks that can’t sync on EP:

EP:~$ sudo busybox devmem 0x2428000000
0xFFFFFFFF

[WayneWWW]

Hi Wilson,

Address 0x2428000000 is valid on RP side only. On EP side, you must access the memory using the virtual address allocated by dma_alloc_coherent().

There is no way to access this memory using command line, please dump the memory in driver itself.