Why is issuing a trap not a priviledged task?

Question

3.1k views Asked by Alexander Suraphel At 26 April 2012 at 20:18

In solutions to a question on the book "Operating Systems Concepts" it indicates that issuing a trap not a privileged task. Why is that so?

There are 2 answers

cnicutar On 26 April 2012 at 20:20

If it were a privileged operation, it wouldn't be possible for a process to issue a system call.

**ChristopheD** · Accepted Answer · 2012-04-26 20:26:14

ChristopheD On 26 April 2012 at 20:26 BEST ANSWER

Some instructions need special privileges to run at all, which most of the time means only the OS gets to execute them.

Most user processes (programs) will need to issue a trap / exception to get the OS to run these instructions.