On Fri, Mar 4, 2011 at 11:19 PM,  [off-list ref] wrote:

I'm not sure if I got your point, but I guess you want to make sure that code activated by your configuration option is included into the kernel image.
Let me illustrate that by example: PC parallel port. ?(Device Drivers-> Parallel Port -> PC-style hardware). This option is associated with CONFIG_PARPORT_PC configuration option. This option includes the following source file drivers/parport/parport_pc.c. Looking at this file you will see that it exports parport_pc_probe_port method.
We can run the following command to see if it was included into the kernel image:
nm vmlinux | grep ?parport_pc_unregister_port
and you will get:
ffffffff8187b5fe r __kstrtab_parport_pc_unregister_port
ffffffff81860080 r __ksymtab_parport_pc_unregister_port
ffffffff81283b58 T parport_pc_unregister_port

when we turn off this option for the ?command
nm vmlinux | grep ?parport_pc_unregister_port
is null

See what you mentioned can be done only if one knows the option
parport_pc_unregister_port
or is aware if where it exists.
Just imagine if the person does not knows the file name or variable
name then how will he get it.
That is what I mentioned.I finally think that I got solution for it.
Just go the concerned option and press a question mark over it.
It will show you in background the variable associated with it.