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phys(2) [bsd man page]

PHYS(2) 							System Calls Manual							   PHYS(2)

phys - allow a process to access physical addresses (2BSD) SYNOPSIS
phys(segreg, size, physaddr) unsigned int segreg, size, physaddr; DESCRIPTION
The argument segreg specifies a process virtual (data-space) address range of 8K bytes starting at virtual address segregx8K bytes. This address range is mapped into physical address physaddrx64 bytes. Only the first sizex64 bytes of this mapping is addressable. If size is zero, any previous mapping of this virtual address range is nullified. For example, the call phys(7, 1, 0177775); will map virtual addresses 0160000-0160077 into physical addresses 017777500-017777577. In particular, virtual address 0160060 is the PDP-11 console located at physical address 017777560. This call may only be executed by the super-user. ERRORS
[EPERM] The process's effective user ID is not the super-user. [EINVAL] Segreg is less than 0 or greater than 7. [EINVAL] Size is less than 0 or greater than 128. SEE ALSO
PDP-11 segmentation hardware BUGS
On systems with ENABLE/34(tm) memory mapping boards, phys cannot be used to map in the I/O page. This system call is very dangerous. It is not considered a permanent part of the system. Phys is unique to the PDP-11 and 2BSD; its use is discouraged. 3rd Berkeley Distribution January 22, 1987 PHYS(2)

Check Out this Related Man Page

MEM(4)							     Kernel Interfaces Manual							    MEM(4)

mem, kmem - main memory SYNOPSIS
major device number(s): raw: 1 minor device encoding: mem: 0; kmem: 1; null: 2 DESCRIPTION
Mem is a special file that is an image of the main memory of the computer. It may be used, for example, to examine (and even to patch) the system. Byte addresses in mem are interpreted as physical memory addresses. References to non-existent locations cause errors to be returned. The file kmem is the same as mem except that kernel virtual memory rather than physical memory is accessed. Only kernel virtual addresses that are mapped to memory are allowed. Examining and patching device registers is likely to lead to unexpected results when read-only or write-only bits are present. On PDP-11s, the I/O page begins at location 0160000 of kmem and the per-process data segment for the current process begins at 0140000 and is USIZE clicks (64 bytes each) long. FILES
/dev/mem /dev/kmem /dev/MAKEDEV script to create special files /dev/MAKEDEV.local script to localize special files BUGS
On PDP-11's, specifying an odd kernel or user address, or an odd transfer count is [generally] slower than using all even parameters. On machines with ENABLE/34(tm) memory mapping boards the I/O page can be accessed only through kmem. 3rd Berkeley Distribution January 28, 1988 MEM(4)

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