3rd-party/linux-kernel-module-cheat
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Announce KGDB!!!

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Ciro Santilli
2017-05-27 07:39:50 +01:00
parent d424380fe6
commit 6cf47f0b33
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README.md
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@@ -1,6 +1,6 @@
# Linux Kernel Module Cheat # Linux Kernel Module Cheat
Run one command, get into QEMU Buildroot BusyBox with several minimal Linux kernel 4.9 module example tutorials with GDB debug support. x86 and ARM guests supported. Tested in Ubuntu 14.04 - 16.10 hosts. Run one command, get into QEMU Buildroot BusyBox with several minimal Linux kernel 4.9 module example tutorials with GDB and KGDB debug. Tested in x86 and ARM guests, Ubuntu 14.04 - 16.10 hosts.
Usage: Usage:
@@ -107,16 +107,15 @@ To have some fun, you can first run inside QEMU:
/count.sh /count.sh
which counts to infinity to stdout, and then: which counts to infinity to stdout, and then in GDB:
Ctrl + C Ctrl + C
break sys_write break sys_write
continue
continue
continue
And now you can control the counting from GDB: And you now control the counting from GDB.
continue
continue
continue
See also: <http://stackoverflow.com/questions/11408041/how-to-debug-the-linux-kernel-with-gdb-and-qemu> See also: <http://stackoverflow.com/questions/11408041/how-to-debug-the-linux-kernel-with-gdb-and-qemu>
@@ -128,8 +127,6 @@ QEMU cannot be put on the background of the current shell, so you will need to o
./rungdb ./rungdb
manually.
### Kernel module debugging ### Kernel module debugging
Loadable kernel modules are a bit trickier since the kernel can place them at different memory locations depending on load other. Loadable kernel modules are a bit trickier since the kernel can place them at different memory locations depending on load other.
@@ -217,7 +214,7 @@ KGDB is kernel dark magic that allows you to GDB the kernel on real hardware wit
It is useless with QEMU since we already have full system visibility with `-gdb`, but this is a good way to learn it. It is useless with QEMU since we already have full system visibility with `-gdb`, but this is a good way to learn it.
Cheaper than JTAG (free) and easier to setup (no wires), but with less visibility as it depends on the kernel working, so e.g.: dies on panic, does not see boot sequence. Cheaper than JTAG (free) and easier to setup (all you need is serial), but with less visibility as it depends on the kernel working, so e.g.: dies on panic, does not see boot sequence.
Usage: Usage:
@@ -248,6 +245,7 @@ If you do: `b sys_write` immediately after `./rungdb -k`, it fails with `KGDB: B
See also: See also:
- <https://github.com/torvalds/linux/blob/v4.9/Documentation/DocBook/kgdb.tmpl> - <https://github.com/torvalds/linux/blob/v4.9/Documentation/DocBook/kgdb.tmpl>
- <https://stackoverflow.com/questions/22004616/qemu-kernel-debugging-with-kgdb/44197715#44197715>
### KGDB kernel modules ### KGDB kernel modules