Kernel configuration changes

The Debian kernel used with SONiC includes almost all available hardware that
can be found on a system using Linux. This increases considerably the time
needed to build the kernel Debian image. Since there are many drivers,
protocols or filesystems which will never be used on a switch, there is a
imple mechanism to remove kernel options which does not require creating a
kernel configuration patch. The options which need to be excluded from the
kernel are simply listed in a flat text file:
patch/kconfig-exclusions

Example:

    CONFIG_REISERFS_FS
    CONFIG_JFS_FS
    CONFIG_XFS_FS

Similarly, there is a mechanism to include some kernel options by listing
these options into the flat text file:
patch/kconfig-inclusions

Example:

    CONFIG_INT340X_THERMAL=m
    CONFIG_LOG_BUF_SHIFT=18

If the files patch/kconfig-exclusions and patch/kconfig-inclusions exist,
they will be processed after all the kernel patches described in the patch
directory have been applied, exclusions being done before inclusions.

Also, the final kernel configuration will be checked to verify that:
- all options asked to be excluded are effectively not present in the kernel,
- and all options asked to be included are effectively present in the kernel,
using the exact type (module or buit-in) or string or number.

Author: olivier-singla

README.md

@@ -5,16 +5,13 @@
 ## Description
 This repository contains the scripts and patches to build the kernel for SONiC. SONiC uses the same kernel for all platforms. We prefer to out-of-tree kernel platform modules. We accept kernel patches on following conditions:
 
-- Existing kernel modules need to be enabled.
-- Existing kernel modules need to be patched and those patches are available in upstream.
-  - Please include the original upstream commit id and message in the patch. This allows the maintainer to remove upstream patches during the kernel upgrade.
-- New kernel modules which are common to all platforms.
-- Platform specific kernel modules which are impossible or very difficul to be built out of kernel tree.
+- Existing kernel modules need to be enabled
+- Existing kernel modules need to be patched and those patches are available in upstream
+- New kernel modules which are common to all platforms
+- Platform specific kernel modules which are impossible or very difficul to be built out of kernel tree
 
 Platform specific kernel modules are expected to develop out-of-tree kernel modules, provide them in debian packages to be embeded into SONiC ONE image and installed on their platforms.
 
-For all patches, please ensure you have run the patch with `checkpatch.pl` and pass it.
-
 Usage:
 
     make DEST=<destination path>