Dailydave mailing list archives
Re: luckily, there are no dumb questions
From: Bruce Ediger <eballen1 () qwest net>
Date: Fri, 8 Jun 2007 09:16:21 -0600 (MDT)
On Thu, 7 Jun 2007 dan () geer org wrote:
How is it so that MS Windows uses only Rings 0 & 3? An engineering answer, a marketing answer, and/or an historical answer would be welcome. Don't know why I never thought to ask before, but I'm asking now. (And if I'm really wrong, please tell me what uses 1|2.)
Here's some (now quite amusing!) material from 1998: http://www.windowsitlibrary.com/Content/435/01/1.html "To effectively support both RISC and Intel CPUs, Windows NT uses only two rings in its design, Rings 0 and 3." I don't know how much credence to lend to early material about NT. It's pretty obvious that marketing drove most of the "technical" stuff available. For example, obvious NT predecessors like Unix and Mach and VMS hardly got a mention in the 1st Edition of "Inside Windows NT". This collection of papers from the "DEC Technical Journal": http://www.hpl.hp.com/hpjournal/dtj/vol4num4/toc.htm doesn't seem to mention "rings" at all, which seems strange. The "RISC" CPU mentioned in the 1998 material is the Alpha. DEC clearly wanted VMS to run on Alpha CPUs, and VMS needed 4 rings. Looks like maybe DEC used "PALcode" to do rings for OpenVMS on Alphas. _______________________________________________ Dailydave mailing list Dailydave () lists immunitysec com http://lists.immunitysec.com/mailman/listinfo/dailydave
Current thread:
- luckily, there are no dumb questions dan (Jun 07)
- Re: luckily, there are no dumb questions Andreas Junestam (Jun 07)
- Re: luckily, there are no dumb questions Andrew Cushman (Jun 07)
- Re: luckily, there are no dumb questions Joanna Rutkowska (Jun 08)
- Re: luckily, there are no dumb questions dan (Jun 08)
- Re: luckily, there are no dumb questions Bruce Ediger (Jun 08)
- Re: luckily, there are no dumb questions Andreas Junestam (Jun 07)