summaryrefslogtreecommitdiffstats
path: root/Documentation/frv/gdbstub.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/frv/gdbstub.txt')
-rw-r--r--Documentation/frv/gdbstub.txt130
1 files changed, 0 insertions, 130 deletions
diff --git a/Documentation/frv/gdbstub.txt b/Documentation/frv/gdbstub.txt
deleted file mode 100644
index b92bfd9..0000000
--- a/Documentation/frv/gdbstub.txt
+++ /dev/null
@@ -1,130 +0,0 @@
- ====================
- DEBUGGING FR-V LINUX
- ====================
-
-
-The kernel contains a GDB stub that talks GDB remote protocol across a serial
-port. This permits GDB to single step through the kernel, set breakpoints and
-trap exceptions that happen in kernel space and interrupt execution. It also
-permits the NMI interrupt button or serial port events to jump the kernel into
-the debugger.
-
-On the CPUs that have on-chip UARTs (FR400, FR403, FR405, FR555), the
-GDB stub hijacks a serial port for its own purposes, and makes it
-generate level 15 interrupts (NMI). The kernel proper cannot see the serial
-port in question under these conditions.
-
-On the MB93091-VDK CPU boards, the GDB stub uses UART1, which would otherwise
-be /dev/ttyS1. On the MB93093-PDK, the GDB stub uses UART0. Therefore, on the
-PDK there is no externally accessible serial port and the serial port to
-which the touch screen is attached becomes /dev/ttyS0.
-
-Note that the GDB stub runs entirely within CPU debug mode, and so should not
-incur any exceptions or interrupts whilst it is active. In particular, note
-that the clock will lose time since it is implemented in software.
-
-
-==================
-KERNEL PREPARATION
-==================
-
-Firstly, a debuggable kernel must be built. To do this, unpack the kernel tree
-and copy the configuration that you wish to use to .config. Then reconfigure
-the following things on the "Kernel Hacking" tab:
-
- (*) "Include debugging information"
-
- Set this to "Y". This causes all C and Assembly files to be compiled
- to include debugging information.
-
- (*) "In-kernel GDB stub"
-
- Set this to "Y". This causes the GDB stub to be compiled into the
- kernel.
-
- (*) "Immediate activation"
-
- Set this to "Y" if you want the GDB stub to activate as soon as possible
- and wait for GDB to connect. This allows you to start tracing right from
- the beginning of start_kernel() in init/main.c.
-
- (*) "Console through GDB stub"
-
- Set this to "Y" if you wish to be able to use "console=gdb0" on the
- command line. That tells the kernel to pass system console messages to
- GDB (which then prints them on its standard output). This is useful when
- debugging the serial drivers that'd otherwise be used to pass console
- messages to the outside world.
-
-Then build as usual, download to the board and execute. Note that if
-"Immediate activation" was selected, then the kernel will wait for GDB to
-attach. If not, then the kernel will boot immediately and GDB will have to
-interrupt it or wait for an exception to occur before doing anything with
-the kernel.
-
-
-=========================
-KERNEL DEBUGGING WITH GDB
-=========================
-
-Set the serial port on the computer that's going to run GDB to the appropriate
-baud rate. Assuming the board's debug port is connected to ttyS0/COM1 on the
-computer doing the debugging:
-
- stty -F /dev/ttyS0 115200
-
-Then start GDB in the base of the kernel tree:
-
- frv-uclinux-gdb linux [uClinux]
-
-Or:
-
- frv-uclinux-gdb vmlinux [MMU linux]
-
-When the prompt appears:
-
- GNU gdb frv-031024
- Copyright 2003 Free Software Foundation, Inc.
- GDB is free software, covered by the GNU General Public License, and you are
- welcome to change it and/or distribute copies of it under certain conditions.
- Type "show copying" to see the conditions.
- There is absolutely no warranty for GDB. Type "show warranty" for details.
- This GDB was configured as "--host=i686-pc-linux-gnu --target=frv-uclinux"...
- (gdb)
-
-Attach to the board like this:
-
- (gdb) target remote /dev/ttyS0
- Remote debugging using /dev/ttyS0
- start_kernel () at init/main.c:395
- (gdb)
-
-This should show the appropriate lines from the source too. The kernel can
-then be debugged almost as if it's any other program.
-
-
-===============================
-INTERRUPTING THE RUNNING KERNEL
-===============================
-
-The kernel can be interrupted whilst it is running, causing a jump back to the
-GDB stub and the debugger:
-
- (*) Pressing Ctrl-C in GDB. This will cause GDB to try and interrupt the
- kernel by sending an RS232 BREAK over the serial line to the GDB
- stub. This will (mostly) immediately interrupt the kernel and return it
- to the debugger.
-
- (*) Pressing the NMI button on the board will also cause a jump into the
- debugger.
-
- (*) Setting a software breakpoint. This sets a break instruction at the
- desired location which the GDB stub then traps the exception for.
-
- (*) Setting a hardware breakpoint. The GDB stub is capable of using the IBAR
- and DBAR registers to assist debugging.
-
-Furthermore, the GDB stub will intercept a number of exceptions automatically
-if they are caused by kernel execution. It will also intercept BUG() macro
-invocation.
-