About TSS Gate

[sturmstiger]

Can anyone tell me what's the difference between task switching using TSS and TSS Gate? Thanks.

[sturmstiger]

By the way,I don't quite understand the use of RPL in selectors.Do I need to give it a value or the CPU would put CPL into it while executing? Thanks.

[sturmstiger]

Do those HD devices use DMA?

[Pype.Clicker]

a TSS gate is a pointer to a TSS. by calling/jumping it, you can do the same operation as if you were calling/jumping the TSS itself, BUT gates can be stored in IDT and LDT while TSS MUST reside in GDT ... so basically, gates are used to give a specific TSS the ability to call another one, even from user level.

The DPL field of the task gate is the required level to call that gate. I guess the DPL filed of the TSS do the same, but i wouldn't set TSS.DPL!=0 if i were you ...