[yocto] machine specific task

[Mircea Gliga]

According to the docs here 
http://www.yoctoproject.org/docs/2.1.1/mega-manual/mega-manual.html#structure-your-layers 
one can specify variables that are machine specific, eg 
KERNEL_DEVICETREE_qemuarm = "versatile-pb.dtb". I can't find a reference 
on how to create a task specific only for a certain machine.
Is there some mechanism to add and execute a custom task just for a 
specific machine, using *addtask* ?

As an alternative, I could check the machine name right in the beginning 
of the do_mycustomtask function, and execute code accordingly, something 
like (pseudo-code):

do_mycustomtask {
     if {MACHINE} != 'myMachineName'
         return;
     # code executing for all other machines
     [...]
}
addtask mycustomtask after do_configure before do_compile

Thanks