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Diffstat (limited to 'docs/system/gdb.rst')
| -rw-r--r-- | docs/system/gdb.rst | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/docs/system/gdb.rst b/docs/system/gdb.rst index 639f814b32..a40145fcf8 100644 --- a/docs/system/gdb.rst +++ b/docs/system/gdb.rst @@ -3,17 +3,25 @@ GDB usage --------- -QEMU has a primitive support to work with gdb, so that you can do -'Ctrl-C' while the virtual machine is running and inspect its state. - -In order to use gdb, launch QEMU with the '-s' option. It will wait for -a gdb connection: +QEMU supports working with gdb via gdb's remote-connection facility +(the "gdbstub"). This allows you to debug guest code in the same +way that you might with a low-level debug facility like JTAG +on real hardware. You can stop and start the virtual machine, +examine state like registers and memory, and set breakpoints and +watchpoints. + +In order to use gdb, launch QEMU with the ``-s`` and ``-S`` options. +The ``-s`` option will make QEMU listen for an incoming connection +from gdb on TCP port 1234, and ``-S`` will make QEMU not start the +guest until you tell it to from gdb. (If you want to specify which +TCP port to use or to use something other than TCP for the gdbstub +connection, use the ``-gdb dev`` option instead of ``-s``.) .. parsed-literal:: - |qemu_system| -s -kernel bzImage -hda rootdisk.img -append "root=/dev/hda" - Connected to host network interface: tun0 - Waiting gdb connection on port 1234 + |qemu_system| -s -S -kernel bzImage -hda rootdisk.img -append "root=/dev/hda" + +QEMU will launch but will silently wait for gdb to connect. Then launch gdb on the 'vmlinux' executable:: |