User:Ignatenkobrain/Kernel/Bisection

About

All packaged kernels for testing you can download from koji

3.9.9 is working fine and the problem occurs with the 3.10.9 upgrade. Let there be 8 patches between 3.9.9 and 3.10.9. When you start to bisect, it enables only half of those patches and you build a kernel with 4 of the 8 patches between those two versions. Now you boot your new compiled kernel and see if you can reproduce the problem. If the kernel is good you take the second half of those 8 patches to build the next kernel, if the kernel is bad you take half of the patches used to narrow down on the patch that causes problems.

For this given example, here is what might happen to find the bad patch (each step you have to build the kernel and reboot into it).

We call the patches 1,2,3,4,5,6,7,8:

• 3.9.9 + 1,2,3,4
• bad → 3.9.9 + 1,2
• good → 3.9.9 + 3,4
• bad → 3.9.9 + 3
• bad → patch 3 it is!

Prepare

Installing git:

# yum install git -y

Usage

Get the git sources

$ cd ~

• Problem with release candidates or with unstable:

$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux

• Problem with stable kernels:

$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git linux

$ cd linux

This creates the folder /usr/src/linux-stable

Start bisect

$ git bisect start
$ git bisect bad v3.10.9
$ git bisect good v3.9.9

Build the kernel

$ export MAKEOPTS="`rpm --eval %{?_smp_mflags}`"
$ curl http://pkgs.fedoraproject.org/cgit/kernel.git/plain/config-generic > .config
$ curl http://pkgs.fedoraproject.org/cgit/kernel.git/plain/config-`arch`-generic >> .config
$ make oldconfig
$ make bzImage && make modules 
# make modules_install && make install
# dracut /boot/initramfs-3.11.0-rc1+.img 3.11.0-rc1+
# depmod -a

• BIOS:

# grub2-mkconfig -o /boot/grub2/grub.cfg

• UEFI:

# grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg

Reboot:

# systemctl reboot

Testing problem..

Bad bisect

$ cd ~/linux
$ git bisect bad

Goto #Build the kernel

Good bisect

$ cd ~/linux
$ git bisect good

Goto #Build the kernel

Unknown bisect

$ cd ~/linux
$ git bisect skip

Goto #Build the kernel

Final bisect

You repeat those steps #Bad bisect and #Good bisect until it shows the content of the bad patch, like shown below (there is more text in the output, this is just half of it).

c630ccf1a127578421a928489d51e99c05037054 is the first bad commit
commit c630ccf1a127578421a928489d51e99c05037054
Author: Stanislaw Gruszka <stf_xl@wp.pl>
Date:   Sat Mar 16 19:19:46 2013 +0100

    rt2800: rearrange bbp/rfcsr initialization
    
    This makes order of initialization of various registers similar like
    on vendor driver.
    
    Based on:
    NICInitializeAsic()
    RT5592LoadRFNormalModeSetup()
    
    from:
    DPO_RT5572_LinuxSTA_2.6.1.3_20121022/common/rtmp_init.c
    DPO_RT5572_LinuxSTA_2.6.1.3_20121022/chip/rt5592.c
    
    Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
    Tested-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
    Signed-off-by: John W. Linville <linville@tuxdriver.com>

:040000 040000 69266bfa97e9e808257f9cfa7196f00222410ebf 7e18f08faa95bb3dd7159381d6085e5b5287809c M      drivers

With this information, you can create a bug report at RHBZ and tell the developers what patch causes problems. The bisect.log file can be attached to the bug report.

Log file

$ cd ~/linux
$ git bisect log > ~/bisect.log

Reset bisect

If you get stuck somewhere or made a mistake, you can reset.

$ cd ~/linux
$ git bisect reset