CV-Bowen opened a new pull request, #18294:
URL: https://github.com/apache/nuttx/pull/18294
## Summary
This PR adds TX/RX timestamp tracking capability to the rpmsg subsystem,
enabling precise latency measurement and debugging for inter-processor
communication.
### Why is this needed?
In multi-core systems using rpmsg for IPC, measuring communication latency
is critical for:
- Performance optimization and bottleneck identification
- Debugging timing-related issues
- Validating real-time requirements
- Profiling message round-trip times
### What does this PR do?
1. **Add generic timestamp API** (`drivers/rpmsg/rpmsg.c`,
`include/nuttx/rpmsg/rpmsg.h`):
- Introduce `struct rpmsg_timestamp_s` with `tx_nsec` and `rx_nsec` fields
- Add `rpmsg_get_timestamp()` API to retrieve buffer timestamps
- Extend `struct rpmsg_ops_s` with `get_timestamp` callback
2. **Implement timestamp support for rpmsg_port**
(`drivers/rpmsg/rpmsg_port.c`, `rpmsg_port.h`):
- Add `rpmsg_port_get_timestamp()` to implement the ops callback
- Add `rpmsg_port_update_timestamp()` helper to record timestamps
- Reserve space for `rpmsg_timestamp_s` in buffer size calculations
3. **Integrate with SPI transport** (`drivers/rpmsg/rpmsg_port_spi.c`,
`rpmsg_port_spi_slave.c`):
- Record TX timestamp before SPI exchange
- Record RX timestamp after receiving data
## Impact
- **Stability**: No impact - new optional feature, existing code paths
unchanged
- **Compatibility**: Backward compatible - timestamp ops callback is
optional (NULL check)
- **Code Quality**: Follows NuttX coding standards, minimal footprint
- **Breaking Changes**: None
## Testing
qemu-armv8a:rpserver and rpproxy
```c
❯ qemu-system-aarch64 -cpu cortex-a53 -nographic \
-machine virt,virtualization=on,gic-version=3 \
-chardev stdio,id=con,mux=on -serial chardev:con \
-object
memory-backend-file,discard-data=on,id=shmmem-shmem0,mem-path=/dev/shm/my_shmem0,size=4194304,share=yes
\
-device ivshmem-plain,id=shmem0,memdev=shmmem-shmem0,addr=0xb \
-device virtio-serial-device,bus=virtio-mmio-bus.0 \
-chardev socket,path=/tmp/rpmsg_port_uart_socket,server=on,wait=off,id=foo \
-device virtconsole,chardev=foo \
-mon chardev=con,mode=readline -kernel ./nuttx/cmake_out/v8a_server/nuttx \
-gdb tcp::7775
[ 0.000000] [ 0] [ INFO] [server] pci_register_rptun_ivshmem_driver:
Register ivshmem driver, id=0, cpuname=proxy, master=1
[ 0.000000] [ 3] [ INFO] [server] pci_scan_bus: pci_scan_bus for bus 0
[ 0.000000] [ 3] [ INFO] [server] pci_scan_bus: class = 00000600,
hdr_type = 00000000
[ 0.000000] [ 3] [ INFO] [server] pci_scan_bus: 00:00 [1b36:0008]
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar0 set bad mask
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar1 set bad mask
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar2 set bad mask
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar3 set bad mask
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar4 set bad mask
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar5 set bad mask
[ 0.000000] [ 3] [ INFO] [server] pci_scan_bus: class = 00000200,
hdr_type = 00000000
[ 0.000000] [ 3] [ INFO] [server] pci_scan_bus: 00:08 [1af4:1000]
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar0:
mask64=fffffffe 32bytes
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar1:
mask64=fffffff0 4096bytes
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar2 set bad mask
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar3 set bad mask
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar4:
mask64=fffffffffffffff0 16384bytes
[ 0.000000] [ 3] [ INFO] [server] pci_scan_bus: class = 00000500,
hdr_type = 00000000
[ 0.000000] [ 3] [ INFO] [server] pci_scan_bus: 00:58 [1af4:1110]
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar0:
mask64=fffffff0 256bytes
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar1 set bad mask
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar2:
mask64=fffffffffffffff0 4194304bytes
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar4 set bad mask
[ 0.000000] [ 3] [ INFO] [server] pci_setup_device: pbar5 set bad mask
[ 0.000000] [ 3] [ INFO] [server] ivshmem_probe: shmem addr=0x8000400000
size=4194304 reg=0x10001000
[ 0.000000] [ 3] [ INFO] [server] rptun_ivshmem_probe: shmem
addr=0x8000400000 size=4194304
NuttShell (NSH) NuttX-12.12.0
server> [ 0.000000] [ 0] [ INFO] [proxy]
pci_register_rptun_ivshmem_driver: Register ivshmem driver, id=0,
cpuname=server, master=0
[ 0.000000] [ 3] [ INFO] [proxy] pci_scan_bus: pci_scan_bus for bus 0
[ 0.000000] [ 3] [ INFO] [proxy] pci_scan_bus: class = 00000600,
hdr_type = 00000000
[ 0.000000] [ 3] [ INFO] [proxy] pci_scan_bus: 00:00 [1b36:0008]
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar0 set bad mask
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar1 set bad mask
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar2 set bad mask
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar3 set bad mask
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar4 set bad mask
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar5 set bad mask
[ 0.000000] [ 3] [ INFO] [proxy] pci_scan_bus: class = 00000200,
hdr_type = 00000000
[ 0.000000] [ 3] [ INFO] [proxy] pci_scan_bus: 00:08 [1af4:1000]
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar0:
mask64=fffffffe 32bytes
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar1:
mask64=fffffff0 4096bytes
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar2 set bad mask
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar3 set bad mask
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar4:
mask64=fffffffffffffff0 16384bytes
[ 0.000000] [ 3] [ INFO] [proxy] pci_scan_bus: class = 00000500,
hdr_type = 00000000
[ 0.000000] [ 3] [ INFO] [proxy] pci_scan_bus: 00:58 [1af4:1110]
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar0:
mask64=fffffff0 256bytes
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar1 set bad mask
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar2:
mask64=fffffffffffffff0 4194304bytes
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar4 set bad mask
[ 0.000000] [ 3] [ INFO] [proxy] pci_setup_device: pbar5 set bad mask
[ 0.000000] [ 3] [ INFO] [proxy] ivshmem_probe: shmem addr=0x8000400000
size=4194304 reg=0x10001000
[ 0.000000] [ 3] [ INFO] [proxy] rptun_ivshmem_probe: shmem
addr=0x8000400000 size=4194304
[ 0.000000] [ 3] [ INFO] [proxy] rptun_ivshmem_probe: Start the wdog
server>
server>
server>
server> rpmsg dump all
[ 0.000000] [ 7] [ EMERG] [server] Local: server Remote: proxy Headrx 7
[ 0.000000] [ 7] [ EMERG] [server] Dump rpmsg info between cpu (master:
yes)server <==> proxy:
[ 0.000000] [ 7] [ EMERG] [server] rpmsg vq RX:
[ 0.000000] [ 7] [ EMERG] [server] VQ: rx_vq - size=8; free=0; queued=0;
desc_head_idx=32768; available_idx=0; avail.idx=15; used_cons_idx=7;
used.idx=7; avail.flags=0x0; used.flags=0x1
[ 0.000000] [ 7] [ EMERG] [server] rpmsg vq TX:
[ 0.000000] [ 7] [ EMERG] [server] VQ: tx_vq - size=8; free=6; queued=0;
desc_head_idx=2; available_idx=0; avail.idx=5; used_cons_idx=3; used.idx=5;
avail.flags=0x1; used.flags=0x0
[ 0.000000] [ 7] [ EMERG] [server] rpmsg ept list:
[ 0.000000] [ 7] [ EMERG] [server] ept NS
[ 0.000000] [ 7] [ EMERG] [server] ept rpmsg-sensor
[ 0.000000] [ 7] [ EMERG] [server] ept rpmsg-ping
[ 0.000000] [ 7] [ EMERG] [server] ept rpmsg-syslog
[ 0.000000] [ 7] [ EMERG] [server] rpmsg buffer list:
[ 0.000000] [ 7] [ EMERG] [server] RX buffer, total 8, pending 0
[ 0.000000] [ 7] [ EMERG] [server] TX buffer, total 8, pending 0
[ 0.000000] [ 7] [ EMERG] [server] Remote: proxy2 state: 1
[ 0.000000] [ 7] [ EMERG] [server] ept NS
[ 0.000000] [ 7] [ EMERG] [server] ept rpmsg-sensor
[ 0.000000] [ 7] [ EMERG] [server] ept rpmsg-ping
[ 0.000000] [ 7] [ EMERG] [server] rpmsg_port queue RX: {used: 0, avail:
8}
[ 0.000000] [ 7] [ EMERG] [server] rpmsg buffer list:
[ 0.000000] [ 7] [ EMERG] [server] rpmsg_port queue TX: {used: 0, avail:
8}
[ 0.000000] [ 7] [ EMERG] [server] rpmsg buffer list:
[ 0.000000] [ 7] [ ALERT] [server] sched_dumpstack: backtrace| 5:
0x00000000402a86c0 0x00000000402aa384 0x000000004029c078 0x000000004028cb04
0x00000000402e3ebc 0x00000000402e3f6c 0x00000000402bcd08 0x00000000402bd190
[ 0.000000] [ 7] [ ALERT] [server] sched_dumpstack: backtrace| 5:
0x00000000402ad044
[ 0.000000] [ 7] [ ALERT] [server] sched_dumpstack: backtrace| 6:
0x00000000402a8ae0 0x00000000402f5fb4 0x00000000402bc0dc 0x00000000402bd278
0x00000000402ad044
server> rpmsg ping all 1 1 1 1
[ 0.000000] [ 7] [ EMERG] [server] ping times: 1
[ 0.000000] [ 7] [ EMERG] [server] buffer_len: 1520, send_len: 17
[ 0.000000] [ 7] [ EMERG] [server] avg: 0 s, 80431136 ns
[ 0.000000] [ 7] [ EMERG] [server] min: 0 s, 80431136 ns
[ 0.000000] [ 7] [ EMERG] [server] max: 0 s, 80431136 ns
[ 0.000000] [ 7] [ EMERG] [server] rate: 0.001690 Mbits/sec
[ 0.000000] [ 7] [ EMERG] [server] ping times: 1
[ 0.000000] [ 7] [ EMERG] [server] buffer_len: 2008, send_len: 17
[ 0.000000] [ 7] [ EMERG] [server] avg: 0 s, 85009936 ns
[ 0.000000] [ 7] [ EMERG] [server] min: 0 s, 85009936 ns
[ 0.000000] [ 7] [ EMERG] [server] max: 0 s, 85009936 ns
[ 0.000000] [ 7] [ EMERG] [server] rate: 0.001599 Mbits/sec
server>
server>
server> uname -a
NuttX server 12.12.0 4b4ce7a50cc Jan 31 2026 21:03:29 arm64 qemu-armv8a
server>
```
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