fix(log): gate packet hexdumps off + grow the log-processing stack

The net image stack-overflowed the log thread at network-up: formatting a queued
message on the deferred log-processing thread (or, in immediate mode, the
emitting SMP/UDP transport thread) exceeded its ~1 KB stack and faulted the
system, so the node joined WiFi, got an IP, then died before it was reachable.

The deepest formatter is the full-packet hex dump (up to ~256 bytes) logged on
every TX and RX. Turn it off by default (MESHTASTIC_PACKET_HEXDUMP default n, was
on whenever the log level was DBG) and document the stack-overflow risk on the
Kconfig and at both call sites. Also give the log-processing thread modest
headroom (CONFIG_LOG_PROCESS_THREAD_STACK_SIZE=2048, was the ~1 KB default).

Verified on a Heltec V3: the net-ota image now boots, joins WiFi, and is
reachable over SMP + telnet with no fault.

Author: roperscrossroads

samples/meshtastic/prj.conf

@@ -9,13 +9,20 @@ CONFIG_LOG_DEFAULT_LEVEL=3
 # messages (bumping a dropped counter) rather than blocking — bump back toward
 # 2048 if `log stats` shows drops that matter.
 CONFIG_LOG_BUFFER_SIZE=1024
+# The deferred log-processing thread formats each message on its own stack; the
+# Zephyr default (~1 KB) is too tight for meshtastic's larger messages and
+# overflowed the log thread at network-up on the V3. Give it modest headroom.
+CONFIG_LOG_PROCESS_THREAD_STACK_SIZE=2048
 
 CONFIG_MAIN_STACK_SIZE=8192
 
 CONFIG_MESHTASTIC=y
 CONFIG_MESHTASTIC_SETTINGS=y
 CONFIG_MESHTASTIC_LOG_LEVEL_DBG=y
-CONFIG_MESHTASTIC_PACKET_HEXDUMP=y
+# Packet hex dumps stay OFF (MESHTASTIC_PACKET_HEXDUMP): dumping a full ~256-byte
+# packet per TX/RX is the deepest formatter on the log path and can overflow the
+# log-thread stack. Enable it (and raise CONFIG_LOG_PROCESS_THREAD_STACK_SIZE)
+# only for wire-level debugging.
 
 # for persistent settings
 CONFIG_NVS=y

src/Kconfig.core

@@ -67,12 +67,22 @@ config MESHTASTIC_OUTBOUND_STACK_SIZE
 
 config MESHTASTIC_PACKET_HEXDUMP
 	bool "Hex dump LoRa wire packets at DBG log level"
-	default MESHTASTIC_LOG_LEVEL_DBG
+	default n
 	help
 	  When enabled and the meshtastic log level is DBG, log a hex dump of
 	  each Meshtastic wire packet (16-byte header plus encrypted payload)
 	  on transmit and receive.
 
+	  WARNING: off by default because it is expensive on the log stack. It
+	  dumps up to the full packet (~256 bytes) on every TX and RX, and
+	  formatting a dump that large is deep on the stack of whichever thread
+	  runs the log backend — the log-processing thread in deferred mode, or the
+	  emitting thread (e.g. the SMP/UDP transport) in immediate mode. With a
+	  tight CONFIG_LOG_PROCESS_THREAD_STACK_SIZE this can overflow that thread's
+	  stack and fault the system (observed at network-up on the Heltec V3).
+	  Enable only for wire-level debugging, and raise
+	  CONFIG_LOG_PROCESS_THREAD_STACK_SIZE if you turn it on.
+
 config MESHTASTIC_DEFAULT_HOP_LIMIT
 	int "Default hop limit for outgoing packets"
 	default 3

src/meshtastic_radio.c

@@ -154,6 +154,8 @@ static void log_wire_tx(const uint8_t *pkt, uint32_t pkt_len)
 	LOG_DBG("LoRa TX %08x->%08x id=%08x ch=0x%02x len=%u",
 		(unsigned int)sys_le32_to_cpu(hdr->src), (unsigned int)sys_le32_to_cpu(hdr->dest),
 		(unsigned int)sys_le32_to_cpu(hdr->id), hdr->channel, (unsigned int)pkt_len);
+	/* Deep log-stack formatter (~256 B) — gated + off by default; see the
+	 * stack-overflow warning on CONFIG_MESHTASTIC_PACKET_HEXDUMP. */
 	LOG_HEXDUMP_DBG(pkt, pkt_len, "LoRa TX");
 }
 #endif /* CONFIG_MESHTASTIC_PACKET_HEXDUMP */

src/meshtastic_router.c

@@ -210,6 +210,8 @@ static void log_wire_rx(const uint8_t *pkt, int len, int16_t rssi, int8_t snr)
 	LOG_DBG("LoRa RX %08x->%08x id=%08x ch=0x%02x len=%d rssi=%d snr=%d",
 		(unsigned int)sys_le32_to_cpu(hdr->src), (unsigned int)sys_le32_to_cpu(hdr->dest),
 		(unsigned int)sys_le32_to_cpu(hdr->id), hdr->channel, len, (int)rssi, (int)snr);
+	/* Deep log-stack formatter (~256 B) — gated + off by default; see the
+	 * stack-overflow warning on CONFIG_MESHTASTIC_PACKET_HEXDUMP. */
 	LOG_HEXDUMP_DBG(pkt, len, "LoRa RX");
 }
 #endif /* CONFIG_MESHTASTIC_PACKET_HEXDUMP */