[FAQ] [参考译文] 【常见问题解答】如何检查 Linux 是否可以通过 RPMsg 与非 Linux 内核通信

软件是否支持 Linux 与非 Linux 内核之间的 RPMsg？  

请参阅 Processor Academy > Multicore > IPC > IPC 基础知识
AM62x ||  AM62Ax ||   AM62Px ||   AM64x

是否有应用程序代码要通过 RPMsg 进行通信？

请参阅 Processor Academy > Multicore > IPC
AM62x ||  AM62Ax ||   AM62Px ||   AM64x

DM R5F：Remoteproc 是否连接到内核？ RPMsg 基础架构是否已初始化？  

这些处理器具有 DM R5F 内核：
AM62x
AM62Ax
AM62Dx
AM62Px
AM67
AM67A

DM R5F 将在引导过程的早期加载、然后才会初始化 Linux。 由于 DM R5F 已在 Linux 引导期间运行、因此 Remoteproc 驱动程序应“连接“到 DM R5F、而不是“初始化“内核。

我们来看看 Linux 成功连接到 DM R5F 并初始化 RPMsg 基础架构的引导的终端输出：

// tested on AM62x RT Linux SDK 10.1
root@am62xx-evm:~# uname -a
Linux am62xx-evm 6.6.58-rt45-ti-rt-01780-gc79d7ef3a56f-dirty #1 SMP PREEMPT_RT Wed Nov 27 14:15:26 UTC 2024 aarch64 GNU/Linux

// search for any terminal output that could be helpful
// I will cut out anything unrelated to DM R5F to keep it simple

root@am62xx-evm:~# dmesg | grep -e r5 -e remoteproc -e rproc -e rpmsg -e virtio
[    0.000000] OF: reserved mem: initialized node r5f-dma-memory@9da00000, compatible id shared-dma-pool
[    0.000000] OF: reserved mem: 0x000000009da00000..0x000000009dafffff (1024 KiB) nomap non-reusable r5f-dma-memory@9da00000
[    0.000000] OF: reserved mem: initialized node r5f-memory@9db00000, compatible id shared-dma-pool
[    0.000000] OF: reserved mem: 0x000000009db00000..0x000000009e6fffff (12288 KiB) nomap non-reusable r5f-memory@9db00000
...

// DM R5F is already running
[   11.099611] platform 78000000.r5f: R5F core may have been powered on by a different host, programmed state (0) != actual state (1)
[   11.102767] platform 78000000.r5f: configured R5F for IPC-only mode
[   11.103001] platform 78000000.r5f: assigned reserved memory node r5f-dma-memory@9da00000
[   11.124169] remoteproc remoteproc1: 78000000.r5f is available
[   11.124363] remoteproc remoteproc1: attaching to 78000000.r5f

// now we are initializing the VIRTIO buffers that are used for RPMsg communication
[   11.125123] rproc-virtio rproc-virtio.3.auto: assigned reserved memory node r5f-dma-memory@9da00000
[   11.136027] virtio_rpmsg_bus virtio1: rpmsg host is online
[   11.136083] rproc-virtio rproc-virtio.3.auto: registered virtio1 (type 7)

// the remoteproc driver successfully attached to DM R5F
[   11.136098] remoteproc remoteproc1: remote processor 78000000.r5f is now attached

// the RPMsg code on the DM R5F defined 2 "endpoints" at 0xD and 0xE
// now Linux creates 2 RPMsg channels to communicate with those 2 endpoints
[   11.136462] virtio_rpmsg_bus virtio1: creating channel ti.ipc4.ping-pong addr 0xd
[   11.136684] virtio_rpmsg_bus virtio1: creating channel rpmsg_chrdev addr 0xe

其他非 Linux 内核： Remoteproc 是否连接到内核？ RPMsg 基础架构是否已初始化？

我们将以 AM62x 上的 M4F 为例。 但这种模式同样适用于所有其他非 Linux 内核。

// tested on AM62x RT Linux SDK 10.1
root@am62xx-evm:~# uname -a
Linux am62xx-evm 6.6.58-rt45-ti-rt-01780-gc79d7ef3a56f-dirty #1 SMP PREEMPT_RT Wed Nov 27 14:15:26 UTC 2024 aarch64 GNU/Linux

// search for any terminal output that could be helpful
// I will cut out anything unrelated to M4F to keep it simple

root@am62xx-evm:~# dmesg | grep -e m4 -e remoteproc -e rproc -e rpmsg -e virtio
[    0.000000] OF: reserved mem: initialized node m4f-dma-memory@9cb00000, compatible id shared-dma-pool
[    0.000000] OF: reserved mem: 0x000000009cb00000..0x000000009cbfffff (1024 KiB) nomap non-reusable m4f-dma-memory@9cb00000
[    0.000000] OF: reserved mem: initialized node m4f-memory@9cc00000, compatible id shared-dma-pool
[    0.000000] OF: reserved mem: 0x000000009cc00000..0x000000009d9fffff (14336 KiB) nomap non-reusable m4f-memory@9cc00000
[   10.608475] k3-m4-rproc 5000000.m4fss: assigned reserved memory node m4f-dma-memory@9cb00000
[   10.608593] k3-m4-rproc 5000000.m4fss: configured M4 for remoteproc mode
[   10.608655] k3-m4-rproc 5000000.m4fss: local reset is deasserted for device
[   10.621124] remoteproc remoteproc0: 5000000.m4fss is available
[   10.658258] remoteproc remoteproc0: powering up 5000000.m4fss
[   10.658328] remoteproc remoteproc0: Booting fw image am62-mcu-m4f0_0-fw, size 55100

// now we are initializing the VIRTIO buffers that are used for RPMsg communication
[   10.689140] rproc-virtio rproc-virtio.1.auto: assigned reserved memory node m4f-dma-memory@9cb00000
[   10.772318] virtio_rpmsg_bus virtio0: rpmsg host is online
[   10.772764] rproc-virtio rproc-virtio.1.auto: registered virtio0 (type 7)

// M4F has been successfully initialized
[   10.772789] remoteproc remoteproc0: remote processor 5000000.m4fss is now up

// the RPMsg code on the M4F defined 2 "endpoints" at 0xD and 0xE
// now Linux creates 2 RPMsg channels to communicate with those 2 endpoints
[   10.772865] virtio_rpmsg_bus virtio0: creating channel ti.ipc4.ping-pong addr 0xd
[   10.773133] virtio_rpmsg_bus virtio0: creating channel rpmsg_chrdev addr 0xe

// note that Linux only has visibility into whether it initialized the M4F subsystem and loaded the firmware
// Linux does NOT have direct visibility into the current state of the M4F software
// so Linux will still say "running" even if the M4F code has crashed

// earlier in the boot log, we saw that remoteproc0 = M4F for this specific boot
root@am62xx-evm:~# cat /sys/class/remoteproc/remoteproc0/state
running