Order-sensitivity of elided device attachments

["John D. Baker" <jdbaker%mylinuxisp.com@localhost>]

If you make kernel configuration files by including another configuration
and use the "no foo* at bar?" syntax to remove a device, there may be
sensitivity to order if you remove both a device and its parent node.

The specific example I've encountered is the case of P2P bridges and
their downstream PCI buses.  If you have a machine that has a PCI bus
but does not (and cannot) have P2P bridges and you wish to elide the
P2P bridges and any potential downstream buses, the proper order is:


# TEST - Test kernel config

include         "arch/<arch>/conf/GENERIC"

no ppb*         at pci?
no pci*         at ppb?


If you reverse the order of these lines, config(1) will get stuck in
a loop executing "do_kill_orphans" until it runs out of memory and
dumps core.

Most machines' GENERIC config has these items in the opposite order from
that shown above and separated by some number of lines in the kernel
config file.

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