Question

Page fault may occur in which of following cases?

i)When requested address is not in RAM

ii)When write is issued on a read-only page

iii)When read to the page is restricted with the current permissions

i only

i and ii only

i and iii only

i,ii and iii

Answer 1

Page fault doesn't only mean that the requested page is not in physical memory. It also applies to cases when the translated address cannot be effectively used say, due to some access restrictions or dirty page bit set.

So, when a write is issued on a read-only page (option ii) or an attempt to read is made on an access restricted page (option iii), a page fault is generated. The process may send some access violation signals (SIGSEGV/SIGBUS or AV exception) which is handled by the OS. The OS may respond to the application by issuing an 'Access Denied' message or may simply terminate the process.

So the answer is option 4 - (i), (ii) and (iii).

Answer 2

ans is all

refer https://en.wikipedia.org/wiki/Page_fault