-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 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 > <[EMAIL PROTECTED]> 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. > - -- 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 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFCM8kShDd4aOud5P8RAon1AKCLNWEbY3Vq32k61m9jN2CbSoD98QCeJT8m mhgyXtmGNFL+RPzJw8md9hE= =B/i5 -----END PGP SIGNATURE----- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/