On Mon, Nov 17, 2008 at 04:09:49PM +0800, Yu Zhao wrote:

On Fri, Nov 14, 2008 at 08:55:38AM +0800, Greg KH wrote:

quoted

On Thu, Nov 13, 2008 at 02:50:24PM +0800, Yu Zhao wrote:

quoted

On Fri, Nov 07, 2008 at 11:18:37AM +0800, Greg KH wrote:

quoted

On Fri, Nov 07, 2008 at 11:01:29AM +0800, Zhao, Yu wrote:

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Currently PCI subsystem has /sys/.../{vendor,device,...} bundled to the 
main PCI device (I suppose this means the entries are created by 
'device_add')

And after the PCI device is announced, 
/sys/.../{config,resourceX,rom,vpd,iov,...} get created depending on if 
these features are supported.

And that's a bug.  Let's not continue to make the same bug here as well.

quoted

Making dynamic entries tie to the main PCI device would require PCI 
subsystem to allocate different 'bus_type' for the devices, right?

No, it would just mean they need to be all added before the device is
fully registered with the driver core.

I looked into the PCI and driver core code again, but didn't figured out how
to do it.

A 'pci_dev' is added by pci_bus_add_device() via device_add(), which creates
sysfs entries according to 'dev_attrs' in the 'pci_bus_type'. If we want those
dynamic entries to appear before the uevent is triggered, we have to bundle
them into the 'dev_attrs'. Is this right way for the dynamic entries? Or I
missed something?

Yes, that is correct.

Or you can add attributes before device_add() is called to the device,
which is probably much easier to do, right?

There are also "conditional" attributes, which get only displayed if
some kind of condition is met, I think you want to use those.

The problem is the sysfs directory of the PCI device is created by the
kobject_add() in the device_add() as follows. And the static entries
bundled with the 'pci_bus_type' are created by the bus_add_device().
Between the kobject_add() and the kobject_uevent(), we don't have any
other choice to add the dynamic entries.

In device_add():

	error = kobject_add(&dev->kobj, dev->kobj.parent, "%s", dev->bus_id);
	...
	error = bus_add_device(dev);
	...
	kobject_uevent(&dev->kobj, KOBJ_ADD);


So looks like the only way is to make the dynamic entries bundled with
the 'pci_bus_type', which means they would become static no matter the
device supports the entries (i.e. corresponding capabilities) or not.

No, this can work, other busses do this.  There are "conditional"
attributes that only get enabled if specific things happen, and you can
add attributes before device_add() is called.  See the scsi code for
examples of both of these options.

thanks,

greg k-h