[gdb] Add ConsoleBuffer pretty-printer for px4_dmesg command

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## 1.3.10
 
+- Add `px4_dmesg` command and pretty printer to display the dmesg buffer in GDB.
 - Add missing SDMMC2 peripheral to STM32F765 SVD file.
 - Add CrashDebug to `killme` command.
 - Limit yoctopuce dependency to v1.0.

src/emdbg/debug/gdb.md

@@ -229,6 +229,36 @@ Pretty prints a table of open files and their private data handle.
 ```
 
 
+### px4_dmesg
+
+```
+px4_dmesg
+```
+
+Prints the dmesg buffer of PX4.
+
+```
+(gdb) px4_dmesg
+$1 = ConsoleBuffer(2394B/4095B: [0 -> 2394]) =
+HW arch: PX4_FMU_V6X
+HW type: V6X010010
+HW version: 0x010
+HW revision: 0x010
+PX4 git-hash: 1cac91d5a9d19dc081bc54d0ea2b7d26ed64c8d8
+PX4 version: 1.14.0 40 (17694784)
+PX4 git-branch: develop
+Vendor version: 3.0.0 64 (50331712)
+OS: NuttX
+OS version: Release 11.0.0 (184549631)
+OS git-hash: b25bc43cd81e257c5e63ac17c7c4331510584af6
+Build datetime: Feb 23 2024 17:18:44
+Build uri: localhost
+Build variant: default
+Toolchain: GNU GCC, 9.3.1 20200408 (release)
+PX4GUID: 000600000000373833333430510d002c0045
+```
+
+
 ### px4_switch_task
 
 ```

src/emdbg/debug/px4/__init__.py

@@ -24,7 +24,7 @@
 
 from .task import all_tasks, all_tasks_as_table, all_files_as_table, task_switch
 from .semaphore import Semaphore
-from .buffer import UartBuffer
+from .buffer import UartBuffer, ConsoleBuffer
 from .device import all_registers, all_registers_as_table, all_gpios_as_table
 from .device import vector_table, vector_table_as_table, Device, coredump
 from .device import discover as discover_device

src/emdbg/debug/px4/buffer.py

@@ -3,6 +3,7 @@
 
 from __future__ import annotations
 from .base import Base
+from .utils import gdb_len
 
 
 class UartBuffer(Base):
@@ -34,3 +35,31 @@ def children(self) -> Iterator[tuple[str, Any]]:
             content = "".join(chr(v) if chr(v).isprintable() else f"\\{v:02x}"
                               for v in content.tobytes())
             yield ("content", content)
+
+
+class ConsoleBuffer(Base):
+    """
+    Pretty Printing Console buffers
+    """
+    def __init__(self, gdb, buf_ptr: "gdb.Value"):
+        super().__init__(gdb)
+        self._buf = buf_ptr
+
+    def to_string(self) -> str:
+        ptr = int(self._buf['_buffer'].address)
+        size = gdb_len(self._buf['_buffer'])
+        head, tail = self._buf['_tail'], self._buf['_head']
+        used = head - tail if (tail <= head) else size - tail + head
+        header = f"ConsoleBuffer({used}B/{size}B: "
+        if tail <= head: header += f"[{tail} -> {head}]) =\n"
+        else: header += f"{head}] <- [{tail}) =\n"
+        if used:
+            if (tail <= head):
+                # [tail, head]
+                content = self.read_memory(ptr + tail, used).tobytes()
+            else:
+                # head], [tail
+                content = self.read_memory(ptr + tail, size - tail).tobytes()
+                content += self.read_memory(ptr, head).tobytes()
+            header += "".join(chr(v) for v in content)
+        return header

src/emdbg/debug/remote/px4.py

@@ -67,6 +67,17 @@ def invoke(self, argument, from_tty):
         else:
             print("No tasks found!")
 
+class PX4_Dmesg(gdb.Command):
+    """
+    Print the dmesg buffer.
+    """
+    def __init__(self):
+        super().__init__("px4_dmesg", gdb.COMMAND_USER)
+
+    @report_exception
+    def invoke(self, argument, from_tty):
+        gdb.execute("print g_console_buffer")
+
 
 class PX4_Registers(gdb.Command):
     """
@@ -325,6 +336,7 @@ def invoke(self, argument, from_tty):
 PX4_Discover()
 PX4_Tasks()
 PX4_Files()
+PX4_Dmesg()
 PX4_Registers()
 PX4_Interrupts()
 PX4_Gpios()
@@ -398,11 +410,13 @@ def invoke(self, argument, from_tty):
 PX4_Reload()
 
 # Pretty Printers
-def _px4_print_semaphore(val):
+def _px4_pretty_printer(val):
     stype = str(val.type)
     if stype == "sem_t" or stype == "struct sem_s":
         return px4.Semaphore(gdb, val)
     if stype == "struct uart_buffer_s":
         return px4.UartBuffer(gdb, val)
+    if stype == "ConsoleBuffer" or stype == "class ConsoleBuffer":
+        return px4.ConsoleBuffer(gdb, val)
     return None
-gdb.pretty_printers.append(_px4_print_semaphore)
+gdb.pretty_printers.append(_px4_pretty_printer)