SCO OpenServer

vtop(D3oddi)

vtop -- convert a virtual address to a physical address

Synopsis

#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/types.h>

paddr_t vtop(caddr_t vaddr, prot_t proc_ptr);

Description

vtop returns a physical address associated with the specified virtual address.

Arguments

vaddr: virtual address to be translated
proc_ptr: pointer to a proc structure (described in <sys/proc.h>) It can be specified as either u.u_procp or as bp->b_proc, where bp is a pointer to the buf structure. This argument can be omitted if vtop is called from user context.

Return values

Normally, vtop returns a physical address.

If the specified virtual address is in the user context of another process (in other words, proc_ptr is not u.u_procp) but there is no physical memory, then 0 (zero) is returned. This can happen, for example, if a portion of the user address space has been swapped out.

If the specified virtual address is in kernel context or in the user context of the current process but there is no associated physical memory, then vtop( ) panics the system.

Usage

The proc_ptr parameter is not examined when vaddr specifies a normal kernel virtual address (meaning an address in the top gigabyte of the virtual address space but not included in the u_area, the kernel stack, or the area reserved for Weitek emulation). To conform with ANSI C syntax, however, the second parameter must always be specified. If you know a that a kernel virtual address is being processed, use kvtophys(D3oddi) instead.

Context and synchronization

All contexts.

If vtop is called with one argument, or with u.u_procp as the proc_ptr, then vtop can only be called from user context.

Hardware applicability

All

Version applicability

oddi: 1, 2, 2mp, 3, 3mp, 4, 4mp, 5, 5mp, 6, 6mp

SVR5 DDI compatibility

vtop(D3) is identical to the SCO OpenServer version in syntax and return values. It is supported for all DDI versions prior to version 8. For DDI 8 and later drivers, ``Scatter/gather operations'' in HDK Technical Reference discusses how to set up a scatter/gather list without using vtop( ).

References

kvtophys(D3oddi)