Re: [RFC v1 01/16] lib: devres: don't enclose pcim_*() functions inCONFIG_HAS_IOPORT

From: Alan Cox
Date: Tue Dec 11 2012 - 12:27:24 EST


> with it. It's very simple. The IO port space is for ISA/PCMCIA and
> PCI IO port regions. It is nothing more than that.

And on a lot of devices the LPC bus.

> Plus, if you _have_ IO space support, you must have some MMIO region for
> them to target - doing what many platforms have done to date and targetted
> ISA IO address 0 at virtual address 0 is just not on because as soon as
> you build a device driver which probes ISA addresses into your kernel,
> you will oops.

There shouldn't really be anything poking around that is modern - this is
true of some PC stuff too.

In general however if its because you have a window partly mapped you
could just catch the exception and load 0xFF for reads (and probably
whine with a backtrace so you know who to moan at).

Alan
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