Re: binary drivers and development

From: John Richard Moser
Date: Thu Mar 10 2005 - 17:45:40 EST

Hash: SHA1

Peter Chubb wrote:
>>>>>>"John" == John Richard Moser <nigelenki@xxxxxxxxxxx> writes:
> John> I've done more thought, here's a small list of advantages on
> John> using binary drivers, specifically considering UDI. You can
> John> consider a different implementation for binary drivers as well,
> John> with most of the same advantages.
> Almost all these advantages are also present for user-mode drivers...
> and getting drivers out of the kernel, where possible, is a much
> better approach IMHO than trying to maintain a leaky in-kernel
> interface. The problem with in-kernel interfaces, even if set in
> concrete, is that any binary driver can go outside the interface ---
> there's no encapsulation --- and so break when the kernel changes.

CPL=3 scares me; context switches are expensive. can they have direct
hardware access? I'm sure a security model to isolate user mode drivers
could be in place. . .

. . . huh. Xen seems to run Linux at CPL=3 and give direct hardware
access, so I guess user mode drivers are possible *shrug*. Linux isn't
a microkernel though.

> Peter C

- --
All content of all messages exchanged herein are left in the
Public Domain, unless otherwise explicitly stated.

Creative brains are a valuable, limited resource. They shouldn't be
wasted on re-inventing the wheel when there are so many fascinating
new problems waiting out there.
-- Eric Steven Raymond
Version: GnuPG v1.2.5 (GNU/Linux)
Comment: Using GnuPG with Thunderbird -

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at