lkml.org 
[lkml]   [1996]   [Jun]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: SVGA kernel chipset drivers.
On Sun, 2 Jun 1996, Marcus Meissner wrote:

> > Maybe this is silly and there exist services that do exactly this, in
> > userspace, in a safe way, and as fast as a kernel trap. Sorry if so, but i
> > think many people dont see the way out [the GGI people for example].
>
> You can just use another selector/segment instead of the default datasegment
> just as WINE does? Ok, will only work on i386 and friends. ...
> (See modify_ldt system call.)

i think if you are on the same priviledge level, then you have access to
those data structures too. You need an extra ldldt instruction to make the
corruption happen, but there is no theoretical barrier.

the only barriers are call gates or interrupt gates to another ring.

Ingo

ps. this is only an issue if the non-framebuffer operations (read
direct GX register access) are performance-critical. (i think they are).




\
 
 \ /
  Last update: 2005-03-22 13:37    [W:0.109 / U:0.404 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site