Re: [PATCH] ISA stubs for ia64

David Mosberger
2004-04-07T17:42:13Z

>>>>> On Wed, 7 Apr 2004 09:09:12 -0600, Bjorn Helgaas <bjorn.helgaas@hp.com> said:

Bjorn> On Tuesday 06 April 2004 5:18 pm, David Mosberger wrote:
>> I don't like this patch at all. The #defines to
>> unsupported_isa_dma_interface() turn compile-time errors into
>> potential runtime errors. With a properly abstracted interface, the
>> ISA-compatibility-macros should not lead to any code in ISA-free
>> systems (and hence there would be no possibility of runtime errors).

Bjorn> True. I actually started by modifying drivers to use CONFIG_ISA to
Bjorn> determine whether to use ISA interfaces, but (a) that leads to a lot
Bjorn> of changes, most of which I can't test and have the potential to break
Bjorn> other arches, and (b) somebody suggested that ISA is sort of a special
Bjorn> case because it hasn't been converted to the driver model.

Bjorn> But I certainly agree that it would be a lot cleaner.

If it's not possible to define ISA-compatibility macros that expand
into no runtime code, I don't see an easy solution. Perhaps we could
at least provide macros such that a driver _can_ be converted to such
a model. It will still require fixing some/many/most drivers with
ISA-support, but to get allmodonf to work, we could just disable a
driver altogether if it depends on ISA and the platform doesn't
support ISA. The cleanup/conversion can then be done incrementally,
as the need arises.

--david