Re: [PATCH] fakephp: Allocate PCI resources before adding the device

["Darrick J. Wong" <djwong@us.ibm.com>]

On Wed, Nov 26, 2008 at 01:56:45AM -0800, Trent Piepho wrote:
> Ok, that makes sense.  The device I'm using fakephp for doesn't have a
> kernel driver so I wouldn't have noticed that.
> 
> Have you tested this with a device that isn't present at boot?  I found
> that I needed to a call to pci_enable_device() after assigning resources,
> otherwise the BARs wouldn't be enabled.  This only happened if the device
> wasn't present at boot time.

Yes, I was actually using this driver to <cough> turn the ioatdma
controller on after turning it off in the BIOS.

> My hardware doesn't run on the latest kernel so I can't test it.  It looks
> like there have been a bunch of pci hotplug changes so back porting this
> might not be feasible.  It also looks a previous patch by Alex Chiang
> completely changed the sysfs interface for fakephp.  I thought sysfs
> interfaces were supposed to be stable?!  Also looks like it made fakephp

I doubt that, sysfs interfaces change all the time.  I think only the
syscall interface has any sort of stability guarantee.

> useless.  How are you supposed to figure out which "fake-n" directory is
> the right one to disable the device you want?

cat /sys/bus/pci/slots/fake*/address

--D