Index: head/sys/dev/sfxge/common/efx_mcdi.h
===================================================================
--- head/sys/dev/sfxge/common/efx_mcdi.h
+++ head/sys/dev/sfxge/common/efx_mcdi.h
@@ -59,6 +59,9 @@
 	uint8_t		*emr_out_buf;
 	size_t		emr_out_length;
 	size_t		emr_out_length_used;
+	/* Internals: low level transport details */
+	unsigned int	emr_err_code;
+	unsigned int	emr_err_arg;
 };
 
 typedef struct efx_mcdi_iface_s {
@@ -82,6 +85,11 @@
 	__in		efx_nic_t *enp,
 	__inout		efx_mcdi_req_t *emrp);
 
+ extern			void
+efx_mcdi_read_response_header(
+	__in		efx_nic_t *enp,
+	__inout		efx_mcdi_req_t *emrp);
+
 extern			void
 efx_mcdi_ev_cpl(
 	__in		efx_nic_t *enp,
Index: head/sys/dev/sfxge/common/efx_mcdi.c
===================================================================
--- head/sys/dev/sfxge/common/efx_mcdi.c
+++ head/sys/dev/sfxge/common/efx_mcdi.c
@@ -228,6 +228,114 @@
 	emcop->emco_request_copyin(enp, emrp, seq, ev_cpl, new_epoch);
 }
 
+
+			void
+efx_mcdi_read_response_header(
+	__in		efx_nic_t *enp,
+	__inout		efx_mcdi_req_t *emrp)
+{
+#if EFSYS_OPT_MCDI_LOGGING
+	const efx_mcdi_transport_t *emtp = enp->en_mcdi.em_emtp;
+#endif /* EFSYS_OPT_MCDI_LOGGING */
+	efx_mcdi_iface_t *emip = &(enp->en_mcdi.em_emip);
+	efx_mcdi_ops_t *emcop = enp->en_mcdi.em_emcop;
+	efx_dword_t hdr[2];
+	unsigned int hdr_len;
+	unsigned int data_len;
+	unsigned int seq;
+	unsigned int cmd;
+	unsigned int error;
+	efx_rc_t rc;
+
+	EFSYS_ASSERT(emrp != NULL);
+
+	emcop->emco_read_response(enp, &hdr[0], 0, sizeof (hdr[0]));
+	hdr_len = sizeof (hdr[0]);
+
+	cmd = EFX_DWORD_FIELD(hdr[0], MCDI_HEADER_CODE);
+	seq = EFX_DWORD_FIELD(hdr[0], MCDI_HEADER_SEQ);
+	error = EFX_DWORD_FIELD(hdr[0], MCDI_HEADER_ERROR);
+
+	if (cmd != MC_CMD_V2_EXTN) {
+		data_len = EFX_DWORD_FIELD(hdr[0], MCDI_HEADER_DATALEN);
+	} else {
+		emcop->emco_read_response(enp, &hdr[1], hdr_len,
+		    sizeof (hdr[1]));
+		hdr_len += sizeof (hdr[1]);
+
+		cmd = EFX_DWORD_FIELD(hdr[1], MC_CMD_V2_EXTN_IN_EXTENDED_CMD);
+		data_len =
+		    EFX_DWORD_FIELD(hdr[1], MC_CMD_V2_EXTN_IN_ACTUAL_LEN);
+	}
+
+	if (error && (data_len == 0)) {
+		/* The MC has rebooted since the request was sent. */
+		EFSYS_SPIN(EFX_MCDI_STATUS_SLEEP_US);
+		emcop->emco_poll_reboot(enp);
+		rc = EIO;
+		goto fail1;
+	}
+	if ((cmd != emrp->emr_cmd) ||
+	    (seq != ((emip->emi_seq - 1) & EFX_MASK32(MCDI_HEADER_SEQ)))) {
+		/* Response is for a different request */
+		rc = EIO;
+		goto fail2;
+	}
+	if (error) {
+		efx_dword_t err[2];
+		unsigned int err_len = MIN(data_len, sizeof (err));
+		int err_code = MC_CMD_ERR_EPROTO;
+		int err_arg = 0;
+
+		/* Read error code (and arg num for MCDI v2 commands) */
+		emcop->emco_read_response(enp, &err, hdr_len, err_len);
+
+		if (err_len >= (MC_CMD_ERR_CODE_OFST + sizeof (efx_dword_t)))
+			err_code = EFX_DWORD_FIELD(err[0], EFX_DWORD_0);
+#ifdef WITH_MCDI_V2
+		if (err_len >= (MC_CMD_ERR_ARG_OFST + sizeof (efx_dword_t)))
+			err_arg = EFX_DWORD_FIELD(err[1], EFX_DWORD_0);
+#endif
+		emrp->emr_err_code = err_code;
+		emrp->emr_err_arg = err_arg;
+
+#if EFSYS_OPT_MCDI_LOGGING
+		if (emtp->emt_logger != NULL) {
+			emtp->emt_logger(emtp->emt_context,
+			    EFX_LOG_MCDI_RESPONSE,
+			    &hdr, hdr_len,
+			    &err, err_len);
+		}
+#endif /* EFSYS_OPT_MCDI_LOGGING */
+
+		if (!emrp->emr_quiet) {
+			EFSYS_PROBE3(mcdi_err_arg, int, emrp->emr_cmd,
+			    int, err_code, int, err_arg);
+		}
+
+		rc = efx_mcdi_request_errcode(err_code);
+		goto fail3;
+	}
+
+	emrp->emr_rc = 0;
+	emrp->emr_out_length_used = data_len;
+	return;
+
+fail3:
+	if (!emrp->emr_quiet)
+		EFSYS_PROBE(fail3);
+fail2:
+	if (!emrp->emr_quiet)
+		EFSYS_PROBE(fail2);
+fail1:
+	if (!emrp->emr_quiet)
+		EFSYS_PROBE1(fail1, efx_rc_t, rc);
+
+	emrp->emr_rc = rc;
+	emrp->emr_out_length_used = 0;
+}
+
+
 	__checkReturn	boolean_t
 efx_mcdi_request_poll(
 	__in		efx_nic_t *enp)
Index: head/sys/dev/sfxge/common/hunt_mcdi.c
===================================================================
--- head/sys/dev/sfxge/common/hunt_mcdi.c
+++ head/sys/dev/sfxge/common/hunt_mcdi.c
@@ -308,11 +308,6 @@
 #endif /* EFSYS_OPT_MCDI_LOGGING */
 	efx_mcdi_iface_t *emip = &(enp->en_mcdi.em_emip);
 	efx_mcdi_req_t *emrp;
-	efx_dword_t hdr[2];
-	unsigned int hdr_len;
-	unsigned int data_len;
-	unsigned int seq;
-	unsigned int cmd;
 	int state;
 	efx_rc_t rc;
 
@@ -332,101 +327,26 @@
 	}
 
 	/* Read the response header */
-	hdr_len = sizeof (hdr[0]);
-	hunt_mcdi_read_response(enp, &hdr[0], 0, hdr_len);
-
-	if (EFX_DWORD_FIELD(hdr[0], MCDI_HEADER_CODE) == MC_CMD_V2_EXTN) {
-		hunt_mcdi_read_response(enp, &hdr[1], hdr_len, sizeof (hdr[1]));
-		hdr_len += sizeof (hdr[1]);
-
-		cmd = EFX_DWORD_FIELD(hdr[1], MC_CMD_V2_EXTN_IN_EXTENDED_CMD);
-		data_len =
-		    EFX_DWORD_FIELD(hdr[1], MC_CMD_V2_EXTN_IN_ACTUAL_LEN);
-	} else {
-		cmd = EFX_DWORD_FIELD(hdr[0], MCDI_HEADER_CODE);
-		data_len = EFX_DWORD_FIELD(hdr[0], MCDI_HEADER_DATALEN);
-	}
+	efx_mcdi_read_response_header(enp, emrp);
 
 	/* Request complete */
 	emip->emi_pending_req = NULL;
-	seq = (emip->emi_seq - 1) & EFX_MASK32(MCDI_HEADER_SEQ);
-
-	/* Check for synchronous reboot */
-	if (EFX_DWORD_FIELD(hdr[0], MCDI_HEADER_ERROR) != 0 && data_len == 0) {
-		/* The MC has rebooted since the request was sent. */
-		EFSYS_SPIN(EFX_MCDI_STATUS_SLEEP_US);
-		hunt_mcdi_poll_reboot(enp);
-
-		EFSYS_UNLOCK(enp->en_eslp, state);
-		rc = EIO;
-		goto fail1;
-	}
 
 	/* Ensure stale MCDI requests fail after an MC reboot. */
 	emip->emi_new_epoch = B_FALSE;
 
 	EFSYS_UNLOCK(enp->en_eslp, state);
 
-	/* Check that the returned data is consistent */
-	if (cmd != emrp->emr_cmd ||
-	    EFX_DWORD_FIELD(hdr[0], MCDI_HEADER_SEQ) != seq) {
-		/* Response is for a different request */
-		rc = EIO;
-		goto fail2;
-	}
-	if (EFX_DWORD_FIELD(hdr[0], MCDI_HEADER_ERROR)) {
-		efx_dword_t err[2];
-		unsigned int err_len = MIN(data_len, sizeof (err));
-		int err_code = MC_CMD_ERR_EPROTO;
-		int err_arg = 0;
-
-		/* Read error code (and arg num for MCDI v2 commands) */
-		hunt_mcdi_read_response(enp, &err[0], hdr_len, err_len);
-
-		if (err_len >= MC_CMD_ERR_CODE_OFST + sizeof (efx_dword_t))
-			err_code = EFX_DWORD_FIELD(err[0], EFX_DWORD_0);
-
-		if (err_len >= MC_CMD_ERR_ARG_OFST + sizeof (efx_dword_t))
-			err_arg = EFX_DWORD_FIELD(err[1], EFX_DWORD_0);
-
-#if EFSYS_OPT_MCDI_LOGGING
-		if (emtp->emt_logger != NULL) {
-			emtp->emt_logger(emtp->emt_context,
-			    EFX_LOG_MCDI_RESPONSE,
-			    &hdr, hdr_len,
-			    &err, err_len);
-		}
-#endif /* EFSYS_OPT_MCDI_LOGGING */
-
-		rc = efx_mcdi_request_errcode(err_code);
-		if (!emrp->emr_quiet) {
-			EFSYS_PROBE3(mcdi_err_arg, int, emrp->emr_cmd,
-			    int, err_code, int, err_arg);
-		}
-		goto fail3;
-
-	} else {
-		emrp->emr_out_length_used = data_len;
-		emrp->emr_rc = 0;
-		hunt_mcdi_request_copyout(enp, emrp);
-	}
+	if ((rc = emrp->emr_rc) != 0)
+		goto fail1;
 
+	hunt_mcdi_request_copyout(enp, emrp);
 	goto out;
 
-fail3:
-	if (!emrp->emr_quiet)
-		EFSYS_PROBE(fail3);
-fail2:
-	if (!emrp->emr_quiet)
-		EFSYS_PROBE(fail2);
 fail1:
 	if (!emrp->emr_quiet)
 		EFSYS_PROBE1(fail1, efx_rc_t, rc);
 
-	/* Fill out error state */
-	emrp->emr_rc = rc;
-	emrp->emr_out_length_used = 0;
-
 	/* Reboot/Assertion */
 	if (rc == EIO || rc == EINTR)
 		efx_mcdi_raise_exception(enp, emrp, rc);
Index: head/sys/dev/sfxge/common/siena_mcdi.c
===================================================================
--- head/sys/dev/sfxge/common/siena_mcdi.c
+++ head/sys/dev/sfxge/common/siena_mcdi.c
@@ -222,15 +222,8 @@
 siena_mcdi_request_poll(
 	__in		efx_nic_t *enp)
 {
-#if EFSYS_OPT_MCDI_LOGGING
-	const efx_mcdi_transport_t *emtp = enp->en_mcdi.em_emtp;
-#endif
 	efx_mcdi_iface_t *emip = &(enp->en_mcdi.em_emip);
 	efx_mcdi_req_t *emrp;
-	efx_dword_t hdr;
-	unsigned int hdr_len;
-	unsigned int data_len;
-	unsigned int seq;
 	int state;
 	efx_rc_t rc;
 
@@ -260,76 +253,19 @@
 	}
 
 	/* Read the response header */
-	hdr_len = sizeof (hdr);
-	siena_mcdi_read_response(enp, &hdr, 0, hdr_len);
+	efx_mcdi_read_response_header(enp, emrp);
 
 	/* Request complete */
 	emip->emi_pending_req = NULL;
-	seq = (emip->emi_seq - 1) & EFX_MASK32(MCDI_HEADER_SEQ);
-
-	/* Check for synchronous reboot */
-	if (EFX_DWORD_FIELD(hdr, MCDI_HEADER_ERROR) != 0 &&
-	    EFX_DWORD_FIELD(hdr, MCDI_HEADER_DATALEN) == 0) {
-		/* Consume status word */
-		EFSYS_SPIN(EFX_MCDI_STATUS_SLEEP_US);
-		siena_mcdi_poll_reboot(enp);
-		EFSYS_UNLOCK(enp->en_eslp, state);
-		rc = EIO;
-		goto fail2;
-	}
 
 	EFSYS_UNLOCK(enp->en_eslp, state);
 
-	/* Check that the returned data is consistent */
-	if (EFX_DWORD_FIELD(hdr, MCDI_HEADER_CODE) != emrp->emr_cmd ||
-	    EFX_DWORD_FIELD(hdr, MCDI_HEADER_SEQ) != seq) {
-		/* Response is for a different request */
-		rc = EIO;
-		goto fail3;
-	}
-
-	data_len = EFX_DWORD_FIELD(hdr, MCDI_HEADER_DATALEN);
-	if (EFX_DWORD_FIELD(hdr, MCDI_HEADER_ERROR)) {
-		efx_dword_t err;
-		int err_code = MC_CMD_ERR_EPROTO;
-		unsigned int err_len = MIN(data_len, sizeof (err));
-
-		/* Read error code */
-		siena_mcdi_read_response(enp, &err, hdr_len, err_len);
-
-		if (err_len >= MC_CMD_ERR_CODE_OFST + sizeof (efx_dword_t))
-			err_code = EFX_DWORD_FIELD(err, EFX_DWORD_0);
-
-#if EFSYS_OPT_MCDI_LOGGING
-		if (emtp->emt_logger != NULL) {
-			emtp->emt_logger(emtp->emt_context,
-			    EFX_LOG_MCDI_RESPONSE,
-			    &hdr, hdr_len,
-			    &err, err_len);
-		}
-#endif /* EFSYS_OPT_MCDI_LOGGING */
-
-		rc = efx_mcdi_request_errcode(err_code);
-		if (!emrp->emr_quiet) {
-			EFSYS_PROBE2(mcdi_err, int, emrp->emr_cmd,
-			    int, err_code);
-		}
-		goto fail4;
-
-	} else {
-		emrp->emr_out_length_used = data_len;
-		emrp->emr_rc = 0;
-		siena_mcdi_request_copyout(enp, emrp);
-	}
+	if ((rc = emrp->emr_rc) != 0)
+		goto fail2;
 
+	siena_mcdi_request_copyout(enp, emrp);
 	goto out;
 
-fail4:
-	if (!emrp->emr_quiet)
-		EFSYS_PROBE(fail4);
-fail3:
-	if (!emrp->emr_quiet)
-		EFSYS_PROBE(fail3);
 fail2:
 	if (!emrp->emr_quiet)
 		EFSYS_PROBE(fail2);
@@ -337,10 +273,6 @@
 	if (!emrp->emr_quiet)
 		EFSYS_PROBE1(fail1, efx_rc_t, rc);
 
-	/* Fill out error state */
-	emrp->emr_rc = rc;
-	emrp->emr_out_length_used = 0;
-
 	/* Reboot/Assertion */
 	if (rc == EIO || rc == EINTR)
 		efx_mcdi_raise_exception(enp, emrp, rc);