1PHYS(2)                       System Calls Manual                      PHYS(2)
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NAME

6       phys - allow a process to access physical addresses
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SYNOPSIS

9       phys(segreg, size, physadr)
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DESCRIPTION

12       The  argument  segreg  specifies a process virtual (data-space) address
13       range of 8K bytes starting at virtual address  segreg×8K  bytes.   This
14       address  range  is mapped into physical address physadr×64 bytes.  Only
15       the first size×64 bytes of this mapping is  addressable.   If  size  is
16       zero,  any previous mapping of this virtual address range is nullified.
17       For example, the call
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19            phys(6, 1, 0177775);
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21       will map virtual  addresses  0160000-0160077  into  physical  addresses
22       017777500-017777577.   In  particular,  virtual  address 0160060 is the
23       PDP-11 console located at physical address 017777560.
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25       This call may only be executed by the super-user.
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SEE ALSO

28       PDP-11 segmentation hardware
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DIAGNOSTICS

31       The function value zero is returned  if  the  physical  mapping  is  in
32       effect.   The  value -1 is returned if not super-user, if segreg is not
33       in the range 0-7, if size is not in the range 0-127, or if  the  speci‐
34       fied segreg is already used for other than a previous call to phys.
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BUGS

37       This  system  call is obviously very machine dependent and very danger‐
38       ous.  This system call is not considered a permanent part of  the  sys‐
39       tem.
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ASSEMBLER

42       (phys = 52.)
43       sys phys; segreg; size; physadr
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47                                     PDP11                             PHYS(2)