Shared RAM on PCIe Endpoint Device: 'devmem: mmap:' error
Hello, I’ve flashed my AGX Orin Dev kit in PCIe endpoint mode using these instructions.
My root complex device is a Jetson Xavier NX.
Both devices use Jetpack 5.1.1, r35.3.1.
Steps I have done for Endpoint setup, in the following order:
- Recompile kernel with the necessary change to
arch/arm64/configs/tegra_defconfig
- Make the necessary change to
p3701.conf.commonto enable EP mode. - Successfully flash the AGX Orin with the above changes. (
sudo ./flash.sh jetson-agx-orin-devkit mmcblk0p1command) - Connect the devices with my custom PCIe cable (designed using PCIe Endpoint Design Guidelines).
- Bootup the Endpoint (AGX Orin).
- Run the following commands on Endpoint:
cd /sys/kernel/config/pci_ep/
mkdir functions/pci_epf_nv_test/func1
echo 0x10de > functions/pci_epf_nv_test/func1/vendorid
echo 0x0001 > functions/pci_epf_nv_test/func1/deviceid
ln -s functions/pci_epf_nv_test/func1 controllers/141a0000.pcie_ep/
echo 1 > controllers/141a0000.pcie_ep/start
- Bootup the Root port (Xavier NX).
- Determine Endpoint BAR address:
nvidia@nvidia-agx-orin:/sys/kernel/config/pci_ep$ sudo dmesg | grep pci_epf_nv_test
[ 168.885340] pci_epf_nv_test pci_epf_nv_test.0: BAR0 RAM phys: 0x17082e000
[ 168.885360] pci_epf_nv_test pci_epf_nv_test.0: BAR0 RAM IOVA: 0xffff0000
[ 168.885405] pci_epf_nv_test pci_epf_nv_test.0: BAR0 RAM virt: 0x00000000c2c53987
- Access the Endpoint RAM - THIS STEP FAILS:
nvidia@nvidia-agx-orin:/sys/kernel/config/pci_ep$ sudo busybox devmem 0x17082e000
devmem: mmap: Operation not permitted
Besides the recompiled kernel step, which I did, is there anything else I may have done wrong?
