Re: binary drivers and development

[Felipe Alfaro Solana]

On Thu, 10 Mar 2005 17:32:39 -0500, John Richard Moser
<nigelenki@xxxxxxxxxxx> wrote:
> 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.

Xen hypervisor runs at Ring0, while the guest OSs it supports run at Ring1.
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