[yocto] SRC_URI_kernel in machine conf

[lothar at denx.de]

Hello Yoctoholics!

Is it possible to declare a kernels' SRC_URI, as also certain functions, 
directly in the machine config, instead of the kernel .bb?

Example: currently I declare the following in a mykernel.bb (derrived 
from kernel.bbclass)
     SRC_URI_mymachine = "git:my-git-repo"
     do_compile_append_mymachine(){
         rm somefile
     }

...is it possible now, to move this specific code into the 
mymachine.conf file, like
     SRC_URI_mykernel = "git:my-git-repo"
     do_compile_mykernel_append(){
         rm somefile
     }

Questions:
1) Is this possible at all?

2) Is it better to use suffix "_mykernel", "_kernel" or 
"_virtual/kernel"?

3) I saw settings sometimes using the suffix "_kernelname" e.g. 
"_linux-yocto" and other times "_virtual/kernel" - what are the 
differences between them? When better use one, when better use the 
other?

BR,
L