Re: [linux-fbdev] [PATCH 2.3.x] fbdev reversion

[Benjamin Herrenschmidt <bh40@calva.net>]

On Wed, Mar 15, 2000, Gabriel Paubert <paubert@iram.es> wrote:

>> #define _IO_BASE       0
>>
>> breaks CHRP and PReP boxes that use plain ISA drivers (inb() and friends).
>
>Indeed, but that's unavoidable. Except that the breakage has to wait for
>2.5 to be acceptable. Given the choice I prefer to break this and properly
>use resources even for drivers which believe that they have to use fixed
>addresses assigned by God, or rather the devil given the mess that the PC
>`architecture' is.

Well, we need a fix _now_ (that I will backport to 2.2.x as soon as
possible too), at least for PowerMacs. The problem of ISA drivers with
legacy hard-coded addresses is indeed a real one, but it can be
temporarily worked around by having the kernel maintaing a separate
mapping of the "old" IO base to the legacy ISA bus if one exist.

We have, I think, no legacy code using /proc/bus/pci, do we ? If I'm
right, then we can chance it to return physical addresses without
breaking anyone so at least we have a temporary fix for XFree. We must
get the kernel<->userland interface right asap so that we don't need to
change XFree again and again.

I'll play a bit with Michel patches next week-end. Unfortunately, I can't
test much on 2.3.x until the OHCI driver is fixed.

Ben.


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