[Info-vax] Intel proposal to simplify x86-64

[Dan Cross]

In article <u5nru2$8od$1 at panix2.panix.com>,
Scott Dorsey <kludge at panix.com> wrote:
>John Dallman <jgd at cix.co.uk> wrote:
>>In article <63a25e5a-2001-451b-b8a7-d6d9e74b02f9n at googlegroups.com>,
>>xyzzy1959 at gmail.com (John Reagan) wrote:
>>
>>> Other than an impact on the boot loader due to the change in 
>>> startup mode, it has essentially no impact on OpenVMS
>>> 
>>> OpenVMS does not use ring 1 or 2.  The 64-bit mode PTEs don't 
>>> include support for ring 1 or 2 today, just ring 0 and 3.
>>
>>Thanks, glad to hear it. 
>
>I'm not necessarily glad to hear it because I like the idea of keeping
>device drivers in a different ring than user processes or kernel....

Sadly, though, x86 rings other than 0 and 3 haven't had much
effect since paging was introduced in the 80386.  It's not like
either the VAX or Alpha, where the execution mode affected, say,
page table access permissions.  With the port-IO mechanism
mainly relegated to legacy devices, and segmentation becoming
basically meaningless, there just isn't much you can do with it.

	- Dan C.