Kernel Patch and Rebuild using FAI

[Jon Jaroker]

Hello,
 
What is the recommended way to patch and rebuild the linux kernel with FAI?
I found some discussions on the wiki and mailing list, but am confused and
do not understand which approach is best.
 
I need to enable handlers in the kernel that improve a driver's performance
and would like to do this using FAI as part of the FAI build process.  The
build is run by Jenkins.  The build must be reproducible, so that my local
workstation build is the same as the Jenkins' build.
 
My challenge is that the build environment's kernel would be different from
the chroot environment's kernel.  I anticipate cross-compile issues.
 
I see some options, but was wondering how others solve this problem or
whether there is documentation that can point me in the right direction.  My
current ideas are:
 
1. Make the build environment's kernel the same as the chroot's and run the
entire build using a single build project.  This has disadvantages, such as
requiring a specific build environment platform and speed (as the kernel
will take long to recompile).

2. Use two separate build environments, one for generating the patched
kernel and another for generating the final build.  
 
Are there simpler approaches?  Can someone clarify the role of 'fai-kernels'
and whether it is an option?
 
Thank you,
Jon