The currently assigned IST stacks are :-
-* DOUBLEFAULT_STACK. EXCEPTION_STKSZ (PAGE_SIZE).
+* ESTACK_DF. EXCEPTION_STKSZ (PAGE_SIZE).
Used for interrupt 8 - Double Fault Exception (#DF).
Using a separate stack allows the kernel to recover from it well enough
in many cases to still output an oops.
-* NMI_STACK. EXCEPTION_STKSZ (PAGE_SIZE).
+* ESTACK_NMI. EXCEPTION_STKSZ (PAGE_SIZE).
Used for non-maskable interrupts (NMI).
middle of switching stacks. Using IST for NMI events avoids making
assumptions about the previous state of the kernel stack.
-* DEBUG_STACK. DEBUG_STKSZ
+* ESTACK_DB. EXCEPTION_STKSZ (PAGE_SIZE).
Used for hardware debug interrupts (interrupt 1) and for software
debug interrupts (INT3).
avoids making assumptions about the previous state of the kernel
stack.
-* MCE_STACK. EXCEPTION_STKSZ (PAGE_SIZE).
+ To handle nested #DB correctly there exist two instances of DB stacks. On
+ #DB entry the IST stackpointer for #DB is switched to the second instance
+ so a nested #DB starts from a clean stack. The nested #DB switches
+ the IST stackpointer to a guard hole to catch triple nesting.
+
+* ESTACK_MCE. EXCEPTION_STKSZ (PAGE_SIZE).
Used for interrupt 18 - Machine Check Exception (#MC).