Re: [PATCH] /proc/bus/pci* changes

Greg KH (
Mon, 14 Jul 2003 10:38:13 -0700

On Mon, Jul 14, 2003 at 01:40:01AM -0400, Albert Cahalan wrote:
> The directory structure may well be finished,
> at least until it is time to remove the old
> interfaces. (in a few years I guess)
> What's missing is the ability to pass cache-control
> info through the mmap() interface. This is useful
> for non-PCI purposes as well. Some thought will be
> required, as there is a set of commonly useful
> settings among all the arch-specific features.

Why would userspace want to do this? Any examples?

> > And are you prepared to patch all of
> > the userspace programs that currently rely on the existing interface
> > (like XFree86 for one)?
> The existing interface STILL WORKS. Apps can
> transition over time, in part or in whole.
> ("in part" meaning to use the old hacks on
> the new pathname, gaining PCI domain support)
> It's important to get the new interface in
> ASAP, so that all the obscure (in-house, etc.)
> user-space drivers can start to transition.
> The X server is less of a worry, because it
> is a very active project.
> > Also, I don't think you are handling the pci domain space in your patch,
> > or am I just missing it?
> You missed it: third paragraph, first email
> Example:
> You have two devices with the same bus
> number (5), device number (4), and function
> number (2). One is in domain 0, and the
> other is in domain 42. You get:
> pci0/bus5/dev4/fn2/config-space
> pci42/bus5/dev4/fn2/config-space
> Depending on what pci_name_bus does with
> the conflict, you'll get one or two symlinks
> from the old name(s). You'll also get some
> correctly-sized files to represent the
> resources. For example:
> pci0/bus5/dev4/fn2/bar0
> pci0/bus5/dev4/fn2/bar1
> pci0/bus5/dev4/fn2/bar2
> pci42/bus5/dev4/fn2/bar0

Any reason for not using the same sysfs naming scheme to keep things

> Here's an attachment:

Which can't be quoted :(

Anyway, I really don't like the huge array you are declaring if we have
pci domains. And I really don't want to apply this until someone shows
me a real use for it. Maybe we should add mmap functions to sysfs? :)


greg k-h
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