Re: binary drivers and development

John Richard Moser
2005-03-10T22:41:16Z

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Peter Chubb wrote:
>>>>>>"John" == John Richard Moser <nigelenki@comcast.net> 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
>
>
>

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