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List:       linux-ia64
Subject:    Re: [PATCH] add legacy I/O and memory access routines to
From:       Benjamin Herrenschmidt <benh () kernel ! crashing ! org>
Date:       2004-12-16 14:55:22
Message-ID: 1103208922.25262.10.camel () gaston
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On Wed, 2004-12-15 at 09:00 -0800, Jesse Barnes wrote:

> Good, because that's exactly what it does.  The arch is responsible for 
> returning the legacy I/O port or legacy ISA memory base address given a 
> pci_dev, which is used as a base for the page offset passed into mmap.  So 
> e.g. mmap(..., 0xa0000) after doing ioctl(fd, PCIIOC_MMAP_IS_LEGACY_MEM, ...) 
> would get you the VGA framebuffer for the device corresponding to 'fd'.

Sounds good... The only thing is a pci_dev may not be available if you
have a PCI->ISA bridge, tho you may just use the pci_dev of the
bridge...

> > There is some work done by Jon Smirl in this area (a VGA access
> > arbitration driver).
> 
> I think Dave Airlie did a version of the vga class driver, and the backend 
> used for /proc/bus/pci could be used for both drivers.  I'm 
> using /proc/bus/pci because it's available now and nearly good enough (i.e. 
> this patch was all I needed to get going).
> 
> Anyway, I'll post another version with Bjorn's suggestion about the ioctl for 
> choosing config or legacy I/O port read/writes, since it looks like the rest 
> of your concerns are dealt with.
> 
> Thanks,
> Jesse
-- 
Benjamin Herrenschmidt <benh@kernel.crashing.org>

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