vm_qmodify Kernel Service

Purpose

Determines whether a mapped file has been changed.

Syntax

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/vmuser.h>

Parameter

Description

The vm_qmodify kernel service performs two tests to determine if a mapped file has been changed:

• The vm_qmodify kernel service first checks the virtual memory object modified bit, which is set whenever a page is written out.
• If the modified bit is 0, the list of page frames holding pages for this virtual memory object are examined to see if any page frame has been modified.

If both tests are false, the vm_qmodify kernel service returns a value of False. Otherwise, this service returns a value of True.

If the virtual memory object modified bit was set, it is reset to 0. The page frame modified bits are not changed.

Execution Environment

The vm_qmodify kernel service can be called from the process environment only.

Return Values