Re: linear vs. logical addresses? how does cpu interpret kernel addrs?

[William Lee Irwin III <wli@holomorphy.com>]

On Tue, Sep 16, 2003 at 06:55:27PM -0700, William Lee Irwin III wrote:
>> You might want to look at intel's volume 3. They're kept in dedicated
>> registers separate from the pointers and used implicitly.

On Tue, Sep 16, 2003 at 07:07:23PM -0700, Ben Johnson wrote:
> I've been reading that too.  The problem is that there are 6 segment
> selector registers and 4 of those are just for data segments.  several
> data segments can be in use simultaneously and they can all have
> different base addresses and limits.  The only explanation I've found so
> far about how a segment is chosen is that logical address are 48-bit
> values, yet sizeof(void *) == 4.  there has to be a way to match up
> pointer with a segment, but I am unable to find it so far.  (maybe I
> need a nap.)

Logical addresses aren't 48-bit; they're just offset from linear (and
vice-versa).

The way the extra data segment registers are used is by explicitly
qualifying operands with segments.


-- wli