gemstonedevteam opened a new pull request, #20183:
URL: https://github.com/apache/nuttx/pull/20183
Five commits: the `drivers/rptun` resource-table sizing change, the AM67
rptun
lowerhalf, the RAT sliding window, an nxstyle fix to a file this PR touches,
and
documentation.
### Summary
* Adds the rptun lowerhalf connecting the R5F to Linux remoteproc over
NAVSS
`mailbox0_cluster3` (R5F TX on FIFO 0 → Linux GIC SPI 109; Linux TX on
FIFO 1 → VIM IRQ 116).
* The mailbox ISR is a strict top half: drain the FIFO, W1C the status,
EOI.
OpenAMP delivery is deferred to HPWORK, because the rpmsg rx stack takes
mutexes and allocates, neither of which is legal in interrupt context.
* The resource table publishes two vdevs (rpmsg and virtio-net) with all
vring
device addresses `FW_RSC_ADDR_ANY`: Linux remoteproc allocates each vring
from the R5F DMA pool and writes the chosen address back before releasing
the core; fixed addresses outside the pool are rejected.
* `drivers/rptun`: `rptun_do_start()` installed the resource table with a
hardcoded `sizeof(struct rptun_rsc_s)`, truncating extended tables that
carry more than the single rpmsg vdev. An optional `get_rsc_size()` op is
added with an `RPTUN_GET_RSC_SIZE` macro that falls back to the old
value,
so drivers using the standard table are unaffected.
* The RAT sliding window addresses a 32-bit R5F against a 64-bit peer:
J722S
maps DDR beyond the first 2 GB at `0x8_8000_0000`, outside the R5F's
addressable space, while Linux freely posts virtio buffers there. Region 0
is dedicated as a 16 MB window at `0xFE000000`, re-aimed per access, with
the window range MPU-mapped Non-cacheable.
* MPU: two Non-cacheable regions cover the shared IPC memory. The R5F is
not
hardware-coherent with the A53; with cacheable mappings NuttX reads stale
`DRIVER_OK`/vring state and the handshake hangs.
### Impact
* Is new feature added? **YES** — rptun/rpmsg IPC for AM67.
* Impact on user? **NO** — the `drivers/rptun` change is an optional op
with a
fallback to the previous behaviour; existing rptun drivers are
unaffected.
* Impact on build? **NO**.
* Impact on hardware? **YES** — arch/arm/am67 and board t3-gem-o1.
* Impact on documentation? **YES** — provided in this PR.
* Impact on security? **NO**.
* Impact on compatibility? **NO** — `RPTUN_GET_RSC_SIZE` falls back to
`sizeof(struct rptun_rsc_s)` when a driver does not implement it.
* Anything else? Per rule 1.7.9, the `drivers/rptun` sizing change and the
AM67
lowerhalf are bundled deliberately: the lowerhalf's extended two-vdev
table
is truncated without it, so neither is functional alone. This is not a
breaking change. Depends on PRs 3–7.
### Testing
```
Build Host(s): Pardus GNU/Linux 25 (Debian 13 base), x86_64, host gcc 14
Toolchain: arm-none-eabi-gcc 14.2.1 20241119 (15:14.2.rel1-1)
Target: arm / TI AM67 (J722S) Cortex-R5F, board t3-gem-o1:nsh
nuttx-apps: 5a7ab4200
Loaded on the main-domain R5F by Linux remoteproc; console on UART-MAIN1.
```
Testing logs before change: no IPC support on this arch.
The version string in the logs is from the tested build; the commits were
GPG-signed afterwards, which rewrites hashes. The code is unchanged.
Testing logs after change:
```
make distclean && ./tools/configure.sh t3-gem-o1:nsh && make -j
-> nuttx ELF 587972 bytes, 0 compiler warnings
Console:
nsh> ls /dev/rptun
/dev/rptun:
r5f
nsh>
nsh> ls /dev/rptun
/dev/rptun:
r5f
nsh>
Test plan result:
console_alive PASS prompt responsive
version PASS NuttX version 0.0.0 488ed91bec Sep 10 2026
13:49:52 t3-gem-o1:nsh
procfs PASS procfs readable
tasks PASS 3 task lines
rptun_node PASS /dev/rptun: r5f
linux_remoteproc PASS remoteproc3 running, fw=j722s-main-r5f0_0-fw,
vdevs=virtio1,virtio2
linux_rpmsg_channels PASS 2 channel(s): virtio1.rpmsg_ctrl.0.0
virtio1.rpmsg_ns.53.53
PASS=7
make distclean && ./tools/configure.sh t3-gem-o1:nsh && make -j
-> nuttx ELF 587972 bytes, 0 compiler warnings
Console:
nsh> ls /dev/rptun
/dev/rptun:
r5f
nsh>
nsh> ls /dev/rptun
/dev/rptun:
r5f
nsh>
Test plan result:
console_alive PASS prompt responsive
version PASS NuttX version 0.0.0 488ed91bec Sep 10 2026
13:49:52 t3-gem-o1:nsh
procfs PASS procfs readable
tasks PASS 3 task lines
rptun_node PASS /dev/rptun: r5f
linux_remoteproc PASS remoteproc3 running, fw=j722s-main-r5f0_0-fw,
vdevs=virtio1,virtio2
linux_rpmsg_channels PASS 2 channel(s): virtio1.rpmsg_ctrl.0.0
virtio1.rpmsg_ns.53.53
PASS=7
```
### PR verification Self-Check
* [x] This PR introduces only one functional change.
* [x] I have updated all required description fields above.
* [x] My PR adheres to Contributing Guidelines and Documentation.
* [ ] My PR is still work in progress (not ready for review).
* [x] My PR is ready for review and can be safely merged into a codebase.
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