Fishwaldo commented on PR #19732:
URL: https://github.com/apache/nuttx/pull/19732#issuecomment-5225210947
Thanks — runtime logs below. Both boots are the same tree, same board and
the same defconfig; the only difference is `drivers/syslog/ramlog.c` reverted
to master's version for the "before" run.
**Before (master's `ramlog.c`)** — the boot stops after two characters and
never recovers:
```
Starting kernel ...
A[
```
That is the entire output. No prompt, no panic, no further progress.
Those two characters locate the fault exactly. From
`arch/risc-v/src/eic7700x/eic7700x_start.c`:
```c
321: showprogress('A'); /* up_putc(), straight
to the UART */
333: _info("Firmware handed off on Hart %d, ..."); /* first syslog write
*/
338: showprogress('B');
344: nx_start();
```
`A` is `up_putc()` and never touches syslog. `[` is the first character of
the `_info()` line entering `ramlog_addbuf()`. `B` never appears, so that call
never returned — the system dies inside the first RAM log write, eleven lines
before `nx_start()`.
This only bites with `CONFIG_RAMLOG_SYSLOG=y`, which is `default n`. That
option is what redirects syslog output into the RAM log, and so it is the only
way `ramlog_addbuf()` is reached this early in boot. Without it the function is
only entered through writes to `/dev/ramlog`, which by definition happen once
there are tasks to make them — which is why this has gone unnoticed.
**After (this PR)** — the same board boots to NSH, and `dmesg` replays 418
lines. The first is the one that used to be fatal:
```
[CPU0] eic7700x_start_s: Firmware handed off on Hart 3, NuttX running on
Hart 0
```
That is the line emitted at 333 above: before `nx_start()`, before the MMU
is enabled, and before the task lists exist — the exact window the patch
guards. And it is not just that the system survives; the bytes written in that
window are still in the buffer to be replayed afterwards.
The EIC7700X port updates will start landing once some of these core fixes I
have opened are merged, one way or another.
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