The Unabridged Pentium 4 IA32 Processor Genealogy

Events that Initiate a Task Switch

There are a number of events that can cause the processor to suspend the current task and start or resume another task. Table 11-1 on page 192 provides a description of each event. The sections that follow detail the sequence of actions taken by the processor when suspending the current task and starting or resuming another one.

Table 11-1. Events that Cause a Task Switch

Event	Description
Far CALL/Far jump to TSS descriptor	If the 16-bit segment portion of a far jump or far CALL selects a TSS descriptor in the GDT, a task switch occurs. The offset portion of the target address is discarded. The processor loads the 16-bit segment selector into the visible portion of the TR and then loads the selected TSS descriptor ...