Re: VGA PCI IO port reservations

["H. Peter Anvin" <hpa@zytor.com>]

Followup to:  <Pine.LNX.4.10.10011172134510.27177-100000@sphinx.mythic-beasts.com>
By author:    Matthew Kirkwood <matthew@hairy.beasts.org>
In newsgroup: linux.dev.kernel
>
> On Fri, 17 Nov 2000, Russell King wrote:
> 
> > Therefore, it should be reserved independent of whether we have the
> > driver loaded/in kernel or not.
> 
> Is this not an argument for a more flexible resource allocation
> API?  One offering both:
> 
>    res = allocate_resource(restype, dev, RES_ALLOC_UNUSED, region);
> 
> and
> 
>    res = allocate_resource(restype, dev_ RES_ALLOC_HW, region);
> 

One way to do this is to treat PCI IO and ISA IO as two separate
address spaces.  The PCI IO address space is a 14-bit address space
(bits 9:8 are always zero) ranging from 0x1000 to 0xFCFF.  ISA IO is a
10-bit space (bits 15:10 are available for the card to use) ranging
from 0x100 to 0x3FF.

VGA cards may be PCI and AGP, but still have allocations in the ISA
range.

	-hpa
-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
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