How to compile and install custom mainline kernel

Get and compile the mainline kernel, git method:

see also: https://wiki.ubuntu.com/KernelTeam/GitKernelBuild I do things a little different (what else is new?).

Prerequisites (Must):

Step 1 is to apt-get update and apt-get dist-upgrade (i.e. make sure everything is up to date)
Step 2

sudo apt-get install fakeroot build-essential crash kexec-tools makedumpfile kernel-wedge

Step 3

sudo apt-get build-dep linux

Step 4

sudo apt-get install git-core libncurses5 libncurses5-dev libelf-dev asciidoc binutils-dev

Prerequisites as of kernel 4.3:

sudo apt-get install libssl-dev

Step 5 - based on not being able to compile on a new 20.04 server installation 2019.12.02

sudo apt install flex bison

Prerequisites (Optional):

sudo apt-get install git-email git-doc

The git part:

mkdir temp-k-git
cd temp-k-git
git clone   git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
cd linux

Never do stuff in the default master branch. Always make some work area.

git checkout -b k44rc8_stock v4.4-rc8

Steal the Ubuntu kernel configuration file (already installed):

ls -l /boot
cp /boot/config-4.4.0-040400rc8-generic .config

Ubuntu config file has full debugging. Makes an enormous kernel and takes twice as long to compile

scripts/config --disable DEBUG_INFO

Special note as of Kernel 4.4 and if compiling using Ubuntu 14.04 (I don't know about 15.10), with an older version of the c compiler: It can not compile with CONFIG_CC_STACKPROTECTOR_STRONG.

scripts/config --disable CC_STACKPROTECTOR_STRONG

Compile the kernel:

time make -j9 bindeb-pkg       <<< Suggest use number of CPUs + 1. Use less for some responsiveness to be left for other uses
                               <<< I always time the kernel build.

or

time make -j9 bindeb-pkg LOCALVERSION=-stock    <<< For a localized verion name append

or

time make -j9 olddefconfig bindeb-pkg LOCALVERSION=-stock   <<< To automatically use defaults for any new config stuff (particuarly useful when bisecting the kernel).

When the build has completed, install it:

sudo dpkg -i ../linux-headers-4.4.0-rc8-stock_4.4.0-rc8-stock-144_amd64.deb
sudo dpkg -i ../linux-image-4.4.0-rc8-stock_4.4.0-rc8-stock-144_amd64.deb

So, at this point we know the mainline kernel compiles O.K., so move onto the custom kernel. Create a new branch, apply the patches and compile:

$ git checkout -b k44rc8_custom v4.4-rc8
Switched to a new branch 'k44rc8_custom'

$ git am plv6_1_3.patch
Applying: cpufreq: intel_pstate: configurable algorithm to get target pstate
$ git am plv6_2_3.patch
Applying: cpufreq: intel_pstate: account for non C0 time
$ git am plv6_3_3.patch
Applying: cpufreq: intel_pstate: Account for IO wait time

$ time make -j9 olddefconfig bindeb-pkg LOCALVERSION=-custom

Note that it is on purpose that I do not do a make clean, as it is desirable to save a lot of time by doing an incremental build. The first compile took 21 minutes and 26 seconds, but the next custom compile took only 4 minutes and 43 seconds.