Re: EDE - Personal Suggestions and Ideas

Eduardo Pereira Habkost
2004-05-27T15:51:28Z

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On Thu, May 27, 2004 at 11:37:42AM +0530, sandeep wrote:
> hi,
> may be i don't quite understand ELKS much being a newbie here, but what's
> complex issue in having multiple segments on elks-8086?
>
> let's assume well behaved program running on elks, that has 4 different
> segments in use (CS, DS, ES, SS) and all the accesses made by it are wrt
> segment registers.
>
> when this program is taken off, it's all the segment registers are also
> saved in context info. apart from this elks kernel also keeps track of the
> extent of these segments used, so that moving segments around in the memory
> is convenient.
>
> next time when the program is brought in, whereever it's corresponding
> segments
> have been placed in memory, segment registers are appropriately set and
> control is passed back to the program via an iret call.
>
> of course some information manipulation is required for implementation of
> this. but we get the flexibility to move the segments around.
>

You are right, but this is true only if you assume that the program
don't try to mess with the segment registers by itself, or store in
memory the values of the segment registers for using them later. That
is what was being discussed.

--
Eduardo

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