Question

If an Operating system provides 32 system calls. How many entries does IDT(Interrupt Descriptor Table) have for these system calls?

Answer 1

Answer:

Zero entries

Explanation:

If the user space wishes to avail of a kernel service, then it executes svc assembly call. For this no need of a table, as executing this call takes one directly to the handler code for this. Associated with the call is a way to pass parameters to the kernel. In the kernel there will be a loom up table, which will execute the kernel equivalent call for that system call.

So no entries in IDT, but a table of system calls will have to be maintained.