kernel

Hacking Linux Kernel

##1. Introduce

  • How to hack the Linux kernel.
  • Stuffs related to Linux kernel development.
  • Useful tools for Linux kernel development.
  • The developing cycle of Linux kernel.

##2. Where is Linux kernel?

##3. Stable Release

  • 2.6.x kernels are maintained by Linus Torvalds.
  • 2.4.x kernels are maintained by Marcelo Tosatt.
  • 2.2.x kernels are maintained by Alan Cox.
  • 2.0.x kernels are maintained by David Weinehall.
  • -stable kernels are maintained by Greg KH.

##4. Patch

  • How to write a patch
  • Apply the patch
  • Patch format

##5. Mailing lists

  • The main list: lkml@vger.kernel.org
  • Read the LKML FAQ before you subscribe.
  • Linux filesystem development: linux-fsdevel@vger. kernel.org
  • linux-netdev: netdev@vger.kernel.org

##6. Advice

  • Alan Cox: “Ignore everyone who tells you kernel hacking is hard, special or
    different. It’s a large program, and bug fixing or driver tweaking can be a
    best starting point. It is however not magic, nor written in a secret language
    that only deep initiates with beards can read.”
  • Be persistent, be patient, please.

##7. module compile
compile dirver “target” for linux-3.10.0-123.el7 :

  • Download kernel code kernel-3.10.0-123.el7.src.rpm
  • rpm -ivh kernel-3.10.0-123.el7.src.rpm
  • cp ~/rpmbuild/SOURCES/linux-3.10.0-123.el7.tar.xz /root/
  • tar xvf linux-3.10.0-123.el7.tar.xz
  • cd /root/linux-3.10.0-123.el7
  • make oldconfig && make prepare
  • make scripts
  • make CONFIG_ISCSI_TARGET=m -C /root/linux-3.10.0-123.el7 M=drivers/target/iscsi

##8. debug
Enable pr_debug macro function:

  • vim /root/linux-3.10.0-123.el7 M=drivers/target/iscsi/Makefile

  • Add code list below:(equal to add #define DEBUG to the file_name.c) 

    CFLAGS_iscsi_target_parameters.o := -DDEBUG
CFLAGS_iscsi_target_seq_pdu_list.o := -DDEBUG
CFLAGS_iscsi_target_tq.o := -DDEBUG
CFLAGS_iscsi_target_auth.o := -DDEBUG
CFLAGS_iscsi_target_datain_values.o := -DDEBUG
CFLAGS_iscsi_target_device.o := -DDEBUG
CFLAGS_iscsi_target_erl0.o := -DDEBUG
CFLAGS_iscsi_target_erl1.o := -DDEBUG
CFLAGS_iscsi_target_erl2.o := -DDEBUG
CFLAGS_iscsi_target_login.o := -DDEBUG
CFLAGS_iscsi_target_nego.o := -DDEBUG
CFLAGS_iscsi_target_nodeattrib.o := -DDEBUG
CFLAGS_iscsi_target_tmr.o := -DDEBUG
CFLAGS_iscsi_target_tpg.o := -DDEBUG
CFLAGS_iscsi_target_util.o := -DDEBUG
CFLAGS_iscsi_target.o := -DDEBUG
CFLAGS_iscsi_target_configfs.o := -DDEBUG
CFLAGS_iscsi_target_stat.o := -DDEBUG
CFLAGS_iscsi_target_transport.o := -DDEBUG

  • Go the this page for more https://www.kernel.org/doc/local/pr_debug.txt

  • Also, you can using printk(KERN_DEBUG "LIO: get auth from line 140\n"); to your source code.

##Reference: