tf_ra
{ "ra", (void *)offsetof(struct trapframe, tf_ra), db_rw_ddbreg, NULL },
db_read_bytes((db_addr_t)&tf->tf_ra, sizeof(ra), (char *)&ra);
tf->tf_ra = (intptr_t)sa->sa_sigdesc[signo].sd_tramp;
tf->tf_ra = fb->fb_reg[FB_RA];
tf->tf_ra = (intptr_t)lwp_trampoline; /* RA */