_R_S3
uc.uc_mcontext.__gregs[_REG_S3] = sc->sc_regs[_R_S3];
{ "s3", (long *)&ddb_regs.r_regs[_R_S3], DB_SETF_REGS, NULL },
gdb_regs[19] = regs->r_regs[_R_S3]; /* S3 */
case _R_S3: /* s3 */
tf->tf_regs[_R_S3], tf->tf_regs[_R_S4], tf->tf_regs[_R_S5]);