Re: [patch] drivers: wait for threaded probes between initcall levels

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

Ar Sad, 2006-10-28 am 22:48 +0200, ysgrifennodd Stefan Richter:
> I hear network interfaces can be selected by their MACs, which are
> globally unique and persistent. Most SCSI hardware has globally unique
> and persistent unit properties too, and udev indeed uses them these days.

You hear incorrectly. The MAC address is only required to be *machine
unique*, please see the 802.1/2 specification documents for more detail.
Distinguishing by card MAC is a hack that works on some systems only.

SCSI is also unreliable for serial numbers because of USB, brain-dead
raid controllers and other devices that fake the same ident for many
devices.

There is another ugly too - many driver/library layers "know" that
during boot the code is not re-entered so has no locking. Before you can
go multi-probe you also have to fix all the locking in the drivers that
have boot time specific functionality (eg IDE).

Alan

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