(tls-cookie) ; on x86, the LDT index
(this :c-type "struct thread *" :length #!+alpha 2 #!-alpha 1)
(next :c-type "struct thread *" :length #!+alpha 2 #!-alpha 1)
+ (state) ; running, stopping, stopped
#!+x86 (pseudo-atomic-atomic)
#!+x86 (pseudo-atomic-interrupted)
(interrupt-data :c-type "struct interrupt_data *"