From: John Richard Moser <nigelenki@comcast.net>
To: Felipe Alfaro Solana <felipe.alfaro@gmail.com>
Cc: Peter Chubb <peter@chubb.wattle.id.au>, linux-kernel@vger.kernel.org
Subject: Re: binary drivers and development
Date: Sun, 13 Mar 2005 00:01:06 -0500 [thread overview]
Message-ID: <4233C912.80706@comcast.net> (raw)
In-Reply-To: <6f6293f105031207535938c687@mail.gmail.com>
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You wanna give me a quick run-down on x86 of CPL and Ring levels? It's
been bugging me. I know they're there and have a basic idea that they
control what a context can do, don't know what CPL stands for, and
there's a visible gap in my knowledge. I like to understand everything,
it makes things easier.
Felipe Alfaro Solana wrote:
> On Thu, 10 Mar 2005 17:32:39 -0500, John Richard Moser
> <nigelenki@comcast.net> 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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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
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-- Eric Steven Raymond
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next prev parent reply other threads:[~2005-03-13 5:00 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-10 16:28 binary drivers and development John Richard Moser
2005-03-10 16:48 ` Greg KH
2005-03-10 17:19 ` John Richard Moser
2005-03-10 17:24 ` Greg KH
2005-03-10 17:02 ` Ralf Baechle
2005-03-10 17:25 ` John Richard Moser
2005-03-10 17:24 ` John Richard Moser
2005-03-10 20:03 ` Diego Calleja
2005-03-10 20:14 ` John Richard Moser
2005-03-10 21:21 ` Lennart Sorensen
2005-03-10 21:42 ` John Richard Moser
2005-03-10 22:31 ` Lee Revell
2005-03-10 21:59 ` Peter Chubb
2005-03-10 22:32 ` John Richard Moser
2005-03-12 15:53 ` Felipe Alfaro Solana
2005-03-13 5:01 ` John Richard Moser [this message]
2005-03-13 7:17 ` Mike Galbraith
2005-03-10 22:45 ` Rik van Riel
2005-03-11 10:39 ` Ben Dooks
2005-03-11 16:39 ` Benedikt Spranger
2005-03-11 16:10 ` Jon Smirl
2005-03-11 9:33 ` [TROLL] " Xavier Bestel
-- strict thread matches above, loose matches on Subject: below --
2005-03-11 4:57 Albert Cahalan
2005-03-19 11:29 ` Eric W. Biederman
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