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SubjectRe: Fwd: Patch to control VGA bus routing and active VGA device.
On Fri, Jan 28, 2005 at 12:33:20PM -0700, Grant Grundler wrote:
> > > If it is intended to work with multiple IO Port address spaces,
> > > then it needs to use the pci_dev->resource[] and mangle that appropriately.
> >
> > There is no resource for some of the I/O port space that cards respond to.
> Yes - I've heard several graphics cards are horrible broken WRT address
> decoding. Are PCI quirks supposed to handle that sort of thing?

No, PCI quirks are for fixing broken things. VGA cards are entitled to
3c0-3df and all their 10-bit aliases. I've been thinking for a while that we should mark the 10-bit aliases of ISA devices as used ... ie:


Unfortunately, that may break some legitimate setups, but is hinted at
being a good idea in the EISA docs I've read. My laptop uses only the
10-bit aliases of motherboard space (x000-x0ff, x400-x4ff, x800-x8ff,
xc00-xcff) for devices, except for the ISA bridge, which gets:
1180-11bf : 0000:00:1f.0
1180-11bf : pnp 00:0b

The K6-2 is similar; only 10-bit aliases of motherboard space except for:
0a79-0a79 : isapnp write

Possibly a better solution (less likely to break things) would be to allow
drivers to reserve the 10-bit aliases too. Something like this:

static inline void request_isa_alias_regions(unsigned long start,
unsigned long n, const char *name)
int base;
for (base = 0x400; base < 0x10000; base += 0x400) {
request_region(base + start, n, name);

and then call that in drivers/video/console/vgacon.c

Russell, would that allay your issues with the kernel io resource database?

"Next the statesmen will invent cheap lies, putting the blame upon
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince
himself that the war is just, and will thank God for the better sleep
he enjoys after this process of grotesque self-deception." -- Mark Twain
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