How the OS Starts a Task

The OS creates a task's TSS in memory and creates a TSS descriptor in the GDT that points to the TSS. It can then select the task for initiation by executing a far jump or a far CALL instruction that selects one of the following:

  • a TSS descriptor in the GDT.

  • a Call Gate descriptor (that points to a TSS descriptor in the GDT) residing in either the GDT or LDT.

  • a Task Gate descriptor residing in either the GDT or LDT.

A detailed description of the actions taken in each of these cases can be found in the chapter entitled “Mechanics of a Task Switch” on page 191.

Get The Unabridged Pentium 4 IA32 Processor Genealogy now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.