Re: Segment override and lldt instruction

Frank Kotler <[email protected]> Sun, 10 Jun 2007 21:14:00 -0400
Newsgroups org.kernel.vger.linux-assembly
Message-ID <[email protected]>
A D wrote:
>>> Frank Kotler wrote:
>>> In "Linux assembly", there is no reason you'd *want* to use a segment
>>> override, or alter a segment register.
>>
>>
>> Hendrik Visage wrote:
>> Not while your program and/or data space  fits in 4GB of memory space ;)
> 
> 
> So please correct my understanding if i'm wrong: it is not possible
> or necessary to override segment register in protected mode but one can do
> the same thing in real mode. right?

Right. (In Windows, you might want to do [fs:somevalue] - Windows uses 
fs for "thread local storage"(???) - a descriptor that does *not* have a 
base of 0, and limit is... 64k-1(???)... I think)

> So if answer is yes, and if more 
> than 4GB
> of memory space is needed for a program how will segmentation register go
> beyond 4gig without override?

Dunno. I'll leave that one to Hendrik. :)

Best,
Frank