OpenFirmware devices and hotplug events

Greg KH greg at
Thu Mar 18 04:10:27 EST 2004

On Wed, Mar 17, 2004 at 08:16:28AM -0800, Dave Hansen wrote:
> On Tue, 2004-03-16 at 22:46, Nathan Lynch wrote:
> > Greg KH wrote:
> > > It looks like a portion of the device-tree is in sysfs today, with the
> > > different busses, right?  It shouldn't be that big of a leap.
> >
> > One sticking point is that sysfs attribute "show" methods are restricted
> > to returning no more than PAGE_SIZE bytes (according to
> > Documentation/filesystems/sysfs.txt).  Assuming that we map Open
> > Firmware properties to sysfs attributes, the device tree representation
> > can easily have attributes in excess of PAGE_SIZE.  Some of these are
> > actually important -- the "ibm,drc-indexes" property enumerates
> > resources (e.g. CPUs, memory) that may be acquired from the hypervisor.
> >   I believe Anton had one of these that was over 600K the other day...
> The thing to remember here is that we're not suggesting that the entire
> /proc/device-tree be copied, verbatim, to sysfs.

Why not?  That's the proper place for it, if you really need it.

> The "ibm,drc-indexes" is a single node in the OpenFirmware tree, but
> why does it need to be one in the sysfs tree?  If it enumerates CPUs
> and memory, then each unit of enumeration would be a likely cantidate
> for a sysfs entry.

They probably aready are, just like all of the pci devices and other
system info that is aready in the /sys/bus tree.


greg k-h

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