devfs user client
devfs user client
- Subject: devfs user client
- From: Kevin Van Vechten <email@hidden>
- Date: Fri, 9 Nov 2001 13:53:33 -0800
Hello Godfrey,
I'm hoping to resurrect discussion about a devfs user client.
The initial steps don't look too bad: make a IODevfs extension which can
modify devfs and a IODevfsUserClient which issues requests to the
extension.
Things get trickier with the bdevsw and cdevsw callbacks. It would be
nice to provide a fairly-high bandwidth mechanism for moving blocks
between the kernel and user land. Also it seems like care should be
taken to help prevent a user process from bogging down the kernel.
When the callbacks are invoked should they send a mach message
describing the event to the user process? The messages could be
handled in code provided by the IODevfsUserClient, which would interpret
the messages and then make calls into the user process similar to the
bdevsw and cdevsw callbacks, maybe even identically, which would allow
for easy porting.
What are your current thoughts on how to implement the bdevsw and cdevsw
callbacks?
Thanks,
Kevin