Re: logical, linear, physical addresses

[aq <aquynh@xxxxxxxxx>]

> > I think there is one question of Kannan unanswered: CS has attribute
> > of "READ-ONLY", and DS has attribute of "READ-WRITE". And we all know
> > that CS and DS point to the same address range (they have the same
> > base address of 0, and same size of 4GB). So they overlap, but how can
> > we still write data in DS segment? Writing to DS, so we write to CS,
> > but CS is READ-ONLY, so the problem would occur, right ??
> 
> The read-only flag is on the descriptor, *NOT* the memory!
> 
> You *don't* write to CS. You write to memory, that can be accessed
> by CS. But you don't write to it through CS. CS does not apply.
> 
> It's in fact the same with pages. There can be two linear addresses,
> that point to the same physical address -- and each of them can have
> different access permissions.

what a great explaination. thank you all :-)

best,
AQ

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