Subject: devices in /kern ?
To: None <>
From: Manuel Bouyer <>
List: tech-kern
Date: 01/27/2005 18:07:25
xen 2.0 allows binding of event channels (in the xen sense) to userlevel
process. On linux this is done by a character special device and I'd like
to keep a compatible interface. In works this way:
when a process opens the device, a new private data structure containing
an event ring is created. IOCTls allows to control the device, and
especially to bind the controlling process to events. Reading the
device will retrieve pending events from the ring (eventually blocking).
events are unmasked by writing a binary mask to the device.
Each processes opening the device has its own even ring and events binding.

For NetBSD I'd like to avoid an entry in /dev, as this would mean adding
this device to i386 binary sets. So I was asking if we can create a
character device in /kern/xen/ (which already exists), of if it's possible
to have the required behavior (especially per-process private data) with
a regular kernfs file.

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference