PSL_NT
tss->__tss_eflags = PSL_MBO | PSL_NT; /* XXX not needed? */
PSL_NT | PSL_VM | PSL_VIF | PSL_VIP)
#define PSL_USERSTATIC (PSL_MBO | PSL_MBZ | PSL_I | PSL_IOPL | PSL_NT | PSL_VM | PSL_VIF | PSL_VIP)
wrmsr(MSR_SFMASK, PSL_NT|PSL_T|PSL_I|PSL_C|PSL_D|PSL_AC);