Physical memory access with SystemV/AT

[Leroy Dorman]

In article <185 at focsys.UUCP>, larry at focsys.UUCP (Larry Williamson) writes:
> I would like to do something like:
> 	shmcreate 0x800000 800000 1048560
> to create a 1Meg shared memory segment at the 8meg address location.

Unless Microport put in a peek/poke-style function in to V/AT,
(the Rel 1.0 from At&t didn't have one)
there's no way to access physical memory from u-space. A device
driver could get to where you want to go by twiddling a selector
to get the right addresses but talking to the driver through
ioctls or writes probably would be too slow

You're right, it sure would be nice to assign a physical memory
location to a segment selector so you can get at it in
large-model user space programs.  Poke, poke, uPort . . :-)
-------------------------------------------------------------------
Eric Dorman				Chekov-"The whole Gamma 7A
University of California, San Diego	   System is, dead, sir.
Scripps Institution of Oceanography	   Just, dead."
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