diff --git a/hw/ipmi/ipmi_bmc_sim.c b/hw/ipmi/ipmi_bmc_sim.c
index cbf2991..1b615f6 100644
--- a/hw/ipmi/ipmi_bmc_sim.c
+++ b/hw/ipmi/ipmi_bmc_sim.c
@@ -153,14 +153,14 @@ typedef struct IPMISensor {
 #define IPMI_WATCHDOG_SENSOR 0
 
 typedef struct IPMIBmcSim IPMIBmcSim;
+typedef struct RspBuffer RspBuffer;
 
 #define MAX_NETFNS 64
 
 typedef struct IPMICmdHandler {
     void (*cmd_handler)(IPMIBmcSim *s,
                         uint8_t *cmd, unsigned int cmd_len,
-                        uint8_t *rsp, unsigned int *rsp_len,
-                        unsigned int max_rsp_len);
+                        RspBuffer *rsp);
     unsigned int cmd_len_min;
 } IPMICmdHandler;
 
@@ -263,22 +263,40 @@ struct IPMIBmcSim {
 #define IPMI_BMC_WATCHDOG_ACTION_POWER_DOWN      2
 #define IPMI_BMC_WATCHDOG_ACTION_POWER_CYCLE     3
 
+struct RspBuffer {
+    uint8_t buffer[MAX_IPMI_MSG_SIZE];
+    unsigned int len;
+};
+
+#define RSP_BUFFER_INITIALIZER { }
 
 /* Add a byte to the response. */
-#define IPMI_ADD_RSP_DATA(b) \
-    do {                                                   \
-        if (*rsp_len >= max_rsp_len) {                     \
-            rsp[2] = IPMI_CC_REQUEST_DATA_TRUNCATED;       \
-            return;                                        \
-        }                                                  \
-        rsp[(*rsp_len)++] = (b);                           \
-    } while (0)
+static inline void rsp_buffer_push(RspBuffer *rsp, uint8_t byte)
+{
+    if (rsp->len >= sizeof(rsp->buffer)) {
+        rsp->buffer[2] = IPMI_CC_REQUEST_DATA_TRUNCATED;
+        return;
+    }
+    rsp->buffer[rsp->len++] = byte;
+}
+
+static inline void rsp_buffer_pushmore(RspBuffer *rsp, uint8_t *bytes,
+                                       unsigned int n)
+{
+    if (rsp->len + n >= sizeof(rsp->buffer)) {
+        rsp->buffer[2] = IPMI_CC_REQUEST_DATA_TRUNCATED;
+        return;
+    }
+
+    memcpy(&rsp->buffer[rsp->len], bytes, n);
+    rsp->len += n;
+}
 
 /* Check that the reservation in the command is valid. */
 #define IPMI_CHECK_RESERVATION(off, r) \
     do {                                                   \
         if ((cmd[off] | (cmd[off + 1] << 8)) != r) {       \
-            rsp[2] = IPMI_CC_INVALID_RESERVATION;          \
+            rsp->buffer[2] = IPMI_CC_INVALID_RESERVATION;     \
             return;                                        \
         }                                                  \
     } while (0)
@@ -606,54 +624,51 @@ static void ipmi_sim_handle_command(IPMIBmc *b,
     IPMIBmcSim *ibs = IPMI_BMC_SIMULATOR(b);
     IPMIInterface *s = ibs->parent.intf;
     IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);
-    uint8_t rsp[MAX_IPMI_MSG_SIZE];
-    unsigned int rsp_len_holder = 0;
-    unsigned int *rsp_len = &rsp_len_holder;
-    unsigned int max_rsp_len = sizeof(rsp);
     const IPMICmdHandler *hdl;
+    RspBuffer rsp = RSP_BUFFER_INITIALIZER;
 
     /* Set up the response, set the low bit of NETFN. */
     /* Note that max_rsp_len must be at least 3 */
-    if (max_rsp_len < 3) {
-        rsp[2] = IPMI_CC_REQUEST_DATA_TRUNCATED;
+    if (sizeof(rsp.buffer) < 3) {
+        rsp.buffer[2] = IPMI_CC_REQUEST_DATA_TRUNCATED;
         goto out;
     }
 
-    IPMI_ADD_RSP_DATA(cmd[0] | 0x04);
-    IPMI_ADD_RSP_DATA(cmd[1]);
-    IPMI_ADD_RSP_DATA(0); /* Assume success */
+    rsp_buffer_push(&rsp, cmd[0] | 0x04);
+    rsp_buffer_push(&rsp, cmd[1]);
+    rsp_buffer_push(&rsp, 0); /* Assume success */
 
     /* If it's too short or it was truncated, return an error. */
     if (cmd_len < 2) {
-        rsp[2] = IPMI_CC_REQUEST_DATA_LENGTH_INVALID;
+        rsp.buffer[2] = IPMI_CC_REQUEST_DATA_LENGTH_INVALID;
         goto out;
     }
     if (cmd_len > max_cmd_len) {
-        rsp[2] = IPMI_CC_REQUEST_DATA_TRUNCATED;
+        rsp.buffer[2] = IPMI_CC_REQUEST_DATA_TRUNCATED;
         goto out;
     }
 
     if ((cmd[0] & 0x03) != 0) {
         /* Only have stuff on LUN 0 */
-        rsp[2] = IPMI_CC_COMMAND_INVALID_FOR_LUN;
+        rsp.buffer[2] = IPMI_CC_COMMAND_INVALID_FOR_LUN;
         goto out;
     }
 
     hdl = ipmi_get_handler(ibs, cmd[0] >> 2, cmd[1]);
     if (!hdl) {
-        rsp[2] = IPMI_CC_INVALID_CMD;
+        rsp.buffer[2] = IPMI_CC_INVALID_CMD;
         goto out;
     }
 
     if (cmd_len < hdl->cmd_len_min) {
-        rsp[2] = IPMI_CC_REQUEST_DATA_LENGTH_INVALID;
+        rsp.buffer[2] = IPMI_CC_REQUEST_DATA_LENGTH_INVALID;
         goto out;
     }
 
-    hdl->cmd_handler(ibs, cmd, cmd_len, rsp, rsp_len, max_rsp_len);
+    hdl->cmd_handler(ibs, cmd, cmd_len, &rsp);
 
  out:
-    k->handle_rsp(s, msg_id, rsp, *rsp_len);
+    k->handle_rsp(s, msg_id, rsp.buffer, rsp.len);
 
     next_timeout(ibs);
 }
@@ -728,86 +743,82 @@ static void ipmi_sim_handle_timeout(IPMIBmcSim *ibs)
 
 static void chassis_capabilities(IPMIBmcSim *ibs,
                                  uint8_t *cmd, unsigned int cmd_len,
-                                 uint8_t *rsp, unsigned int *rsp_len,
-                                 unsigned int max_rsp_len)
+                                 RspBuffer *rsp)
 {
-    IPMI_ADD_RSP_DATA(0);
-    IPMI_ADD_RSP_DATA(ibs->parent.slave_addr);
-    IPMI_ADD_RSP_DATA(ibs->parent.slave_addr);
-    IPMI_ADD_RSP_DATA(ibs->parent.slave_addr);
-    IPMI_ADD_RSP_DATA(ibs->parent.slave_addr);
+    rsp_buffer_push(rsp, 0);
+    rsp_buffer_push(rsp, ibs->parent.slave_addr);
+    rsp_buffer_push(rsp, ibs->parent.slave_addr);
+    rsp_buffer_push(rsp, ibs->parent.slave_addr);
+    rsp_buffer_push(rsp, ibs->parent.slave_addr);
 }
 
 static void chassis_status(IPMIBmcSim *ibs,
                            uint8_t *cmd, unsigned int cmd_len,
-                           uint8_t *rsp, unsigned int *rsp_len,
-                           unsigned int max_rsp_len)
+                           RspBuffer *rsp)
 {
-    IPMI_ADD_RSP_DATA(0x61); /* Unknown power restore, power is on */
-    IPMI_ADD_RSP_DATA(0);
-    IPMI_ADD_RSP_DATA(0);
-    IPMI_ADD_RSP_DATA(0);
+    rsp_buffer_push(rsp, 0x61); /* Unknown power restore, power is on */
+    rsp_buffer_push(rsp, 0);
+    rsp_buffer_push(rsp, 0);
+    rsp_buffer_push(rsp, 0);
 }
 
 static void chassis_control(IPMIBmcSim *ibs,
                             uint8_t *cmd, unsigned int cmd_len,
-                            uint8_t *rsp, unsigned int *rsp_len,
-                            unsigned int max_rsp_len)
+                            RspBuffer *rsp)
 {
     IPMIInterface *s = ibs->parent.intf;
     IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);
 
     switch (cmd[2] & 0xf) {
     case 0: /* power down */
-        rsp[2] = k->do_hw_op(s, IPMI_POWEROFF_CHASSIS, 0);
+        rsp->buffer[2] = k->do_hw_op(s, IPMI_POWEROFF_CHASSIS, 0);
         break;
     case 1: /* power up */
-        rsp[2] = k->do_hw_op(s, IPMI_POWERON_CHASSIS, 0);
+        rsp->buffer[2] = k->do_hw_op(s, IPMI_POWERON_CHASSIS, 0);
         break;
     case 2: /* power cycle */
-        rsp[2] = k->do_hw_op(s, IPMI_POWERCYCLE_CHASSIS, 0);
+        rsp->buffer[2] = k->do_hw_op(s, IPMI_POWERCYCLE_CHASSIS, 0);
         break;
     case 3: /* hard reset */
-        rsp[2] = k->do_hw_op(s, IPMI_RESET_CHASSIS, 0);
+        rsp->buffer[2] = k->do_hw_op(s, IPMI_RESET_CHASSIS, 0);
         break;
     case 4: /* pulse diagnostic interrupt */
-        rsp[2] = k->do_hw_op(s, IPMI_PULSE_DIAG_IRQ, 0);
+        rsp->buffer[2] = k->do_hw_op(s, IPMI_PULSE_DIAG_IRQ, 0);
         break;
     case 5: /* soft shutdown via ACPI by overtemp emulation */
-        rsp[2] = k->do_hw_op(s,
+        rsp->buffer[2] = k->do_hw_op(s,
                              IPMI_SHUTDOWN_VIA_ACPI_OVERTEMP, 0);
         break;
     default:
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
 }
 
 static void chassis_get_sys_restart_cause(IPMIBmcSim *ibs,
                            uint8_t *cmd, unsigned int cmd_len,
-                           uint8_t *rsp, unsigned int *rsp_len,
-                           unsigned int max_rsp_len)
+                           RspBuffer *rsp)
+
 {
-    IPMI_ADD_RSP_DATA(ibs->restart_cause & 0xf); /* Restart Cause */
-    IPMI_ADD_RSP_DATA(0);  /* Channel 0 */
+    rsp_buffer_push(rsp, ibs->restart_cause & 0xf); /* Restart Cause */
+    rsp_buffer_push(rsp, 0);  /* Channel 0 */
 }
 
 static void get_device_id(IPMIBmcSim *ibs,
                           uint8_t *cmd, unsigned int cmd_len,
-                          uint8_t *rsp, unsigned int *rsp_len,
-                          unsigned int max_rsp_len)
-{
-    IPMI_ADD_RSP_DATA(ibs->device_id);
-    IPMI_ADD_RSP_DATA(ibs->device_rev & 0xf);
-    IPMI_ADD_RSP_DATA(ibs->fwrev1 & 0x7f);
-    IPMI_ADD_RSP_DATA(ibs->fwrev2);
-    IPMI_ADD_RSP_DATA(ibs->ipmi_version);
-    IPMI_ADD_RSP_DATA(0x07); /* sensor, SDR, and SEL. */
-    IPMI_ADD_RSP_DATA(ibs->mfg_id[0]);
-    IPMI_ADD_RSP_DATA(ibs->mfg_id[1]);
-    IPMI_ADD_RSP_DATA(ibs->mfg_id[2]);
-    IPMI_ADD_RSP_DATA(ibs->product_id[0]);
-    IPMI_ADD_RSP_DATA(ibs->product_id[1]);
+                          RspBuffer *rsp)
+{
+    rsp_buffer_push(rsp, ibs->device_id);
+    rsp_buffer_push(rsp, ibs->device_rev & 0xf);
+    rsp_buffer_push(rsp, ibs->fwrev1 & 0x7f);
+    rsp_buffer_push(rsp, ibs->fwrev2);
+    rsp_buffer_push(rsp, ibs->ipmi_version);
+    rsp_buffer_push(rsp, 0x07); /* sensor, SDR, and SEL. */
+    rsp_buffer_push(rsp, ibs->mfg_id[0]);
+    rsp_buffer_push(rsp, ibs->mfg_id[1]);
+    rsp_buffer_push(rsp, ibs->mfg_id[2]);
+    rsp_buffer_push(rsp, ibs->product_id[0]);
+    rsp_buffer_push(rsp, ibs->product_id[1]);
 }
 
 static void set_global_enables(IPMIBmcSim *ibs, uint8_t val)
@@ -826,8 +837,7 @@ static void set_global_enables(IPMIBmcSim *ibs, uint8_t val)
 
 static void cold_reset(IPMIBmcSim *ibs,
                        uint8_t *cmd, unsigned int cmd_len,
-                       uint8_t *rsp, unsigned int *rsp_len,
-                       unsigned int max_rsp_len)
+                       RspBuffer *rsp)
 {
     IPMIInterface *s = ibs->parent.intf;
     IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);
@@ -842,8 +852,7 @@ static void cold_reset(IPMIBmcSim *ibs,
 
 static void warm_reset(IPMIBmcSim *ibs,
                        uint8_t *cmd, unsigned int cmd_len,
-                       uint8_t *rsp, unsigned int *rsp_len,
-                       unsigned int max_rsp_len)
+                       RspBuffer *rsp)
 {
     IPMIInterface *s = ibs->parent.intf;
     IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);
@@ -853,55 +862,49 @@ static void warm_reset(IPMIBmcSim *ibs,
     }
 }
 static void set_acpi_power_state(IPMIBmcSim *ibs,
-                          uint8_t *cmd, unsigned int cmd_len,
-                          uint8_t *rsp, unsigned int *rsp_len,
-                          unsigned int max_rsp_len)
+                                 uint8_t *cmd, unsigned int cmd_len,
+                                 RspBuffer *rsp)
 {
     ibs->acpi_power_state[0] = cmd[2];
     ibs->acpi_power_state[1] = cmd[3];
 }
 
 static void get_acpi_power_state(IPMIBmcSim *ibs,
-                          uint8_t *cmd, unsigned int cmd_len,
-                          uint8_t *rsp, unsigned int *rsp_len,
-                          unsigned int max_rsp_len)
+                                 uint8_t *cmd, unsigned int cmd_len,
+                                 RspBuffer *rsp)
 {
-    IPMI_ADD_RSP_DATA(ibs->acpi_power_state[0]);
-    IPMI_ADD_RSP_DATA(ibs->acpi_power_state[1]);
+    rsp_buffer_push(rsp, ibs->acpi_power_state[0]);
+    rsp_buffer_push(rsp, ibs->acpi_power_state[1]);
 }
 
 static void get_device_guid(IPMIBmcSim *ibs,
-                          uint8_t *cmd, unsigned int cmd_len,
-                          uint8_t *rsp, unsigned int *rsp_len,
-                          unsigned int max_rsp_len)
+                            uint8_t *cmd, unsigned int cmd_len,
+                            RspBuffer *rsp)
 {
     unsigned int i;
 
     for (i = 0; i < 16; i++) {
-        IPMI_ADD_RSP_DATA(ibs->uuid[i]);
+        rsp_buffer_push(rsp, ibs->uuid[i]);
     }
 }
 
 static void set_bmc_global_enables(IPMIBmcSim *ibs,
                                    uint8_t *cmd, unsigned int cmd_len,
-                                   uint8_t *rsp, unsigned int *rsp_len,
-                                   unsigned int max_rsp_len)
+                                   RspBuffer *rsp)
 {
     set_global_enables(ibs, cmd[2]);
 }
 
 static void get_bmc_global_enables(IPMIBmcSim *ibs,
                                    uint8_t *cmd, unsigned int cmd_len,
-                                   uint8_t *rsp, unsigned int *rsp_len,
-                                   unsigned int max_rsp_len)
+                                   RspBuffer *rsp)
 {
-    IPMI_ADD_RSP_DATA(ibs->bmc_global_enables);
+    rsp_buffer_push(rsp, ibs->bmc_global_enables);
 }
 
 static void clr_msg_flags(IPMIBmcSim *ibs,
                           uint8_t *cmd, unsigned int cmd_len,
-                          uint8_t *rsp, unsigned int *rsp_len,
-                          unsigned int max_rsp_len)
+                          RspBuffer *rsp)
 {
     IPMIInterface *s = ibs->parent.intf;
     IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);
@@ -912,27 +915,25 @@ static void clr_msg_flags(IPMIBmcSim *ibs,
 
 static void get_msg_flags(IPMIBmcSim *ibs,
                           uint8_t *cmd, unsigned int cmd_len,
-                          uint8_t *rsp, unsigned int *rsp_len,
-                          unsigned int max_rsp_len)
+                          RspBuffer *rsp)
 {
-    IPMI_ADD_RSP_DATA(ibs->msg_flags);
+    rsp_buffer_push(rsp, ibs->msg_flags);
 }
 
 static void read_evt_msg_buf(IPMIBmcSim *ibs,
                              uint8_t *cmd, unsigned int cmd_len,
-                             uint8_t *rsp, unsigned int *rsp_len,
-                            unsigned int max_rsp_len)
+                             RspBuffer *rsp)
 {
     IPMIInterface *s = ibs->parent.intf;
     IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);
     unsigned int i;
 
     if (!(ibs->msg_flags & IPMI_BMC_MSG_FLAG_EVT_BUF_FULL)) {
-        rsp[2] = 0x80;
+        rsp->buffer[2] = 0x80;
         return;
     }
     for (i = 0; i < 16; i++) {
-        IPMI_ADD_RSP_DATA(ibs->evtbuf[i]);
+        rsp_buffer_push(rsp, ibs->evtbuf[i]);
     }
     ibs->msg_flags &= ~IPMI_BMC_MSG_FLAG_EVT_BUF_FULL;
     k->set_atn(s, attn_set(ibs), attn_irq_enabled(ibs));
@@ -940,21 +941,18 @@ static void read_evt_msg_buf(IPMIBmcSim *ibs,
 
 static void get_msg(IPMIBmcSim *ibs,
                     uint8_t *cmd, unsigned int cmd_len,
-                    uint8_t *rsp, unsigned int *rsp_len,
-                    unsigned int max_rsp_len)
+                    RspBuffer *rsp)
 {
     IPMIRcvBufEntry *msg;
 
     qemu_mutex_lock(&ibs->lock);
     if (QTAILQ_EMPTY(&ibs->rcvbufs)) {
-        rsp[2] = 0x80; /* Queue empty */
+        rsp->buffer[2] = 0x80; /* Queue empty */
         goto out;
     }
-    rsp[3] = 0; /* Channel 0 */
-    *rsp_len += 1;
+    rsp_buffer_push(rsp, 0); /* Channel 0 */
     msg = QTAILQ_FIRST(&ibs->rcvbufs);
-    memcpy(rsp + 4, msg->buf, msg->len);
-    *rsp_len += msg->len;
+    rsp_buffer_pushmore(rsp, msg->buf, msg->len);
     QTAILQ_REMOVE(&ibs->rcvbufs, msg, entry);
     g_free(msg);
 
@@ -983,8 +981,7 @@ ipmb_checksum(unsigned char *data, int size, unsigned char csum)
 
 static void send_msg(IPMIBmcSim *ibs,
                      uint8_t *cmd, unsigned int cmd_len,
-                     uint8_t *rsp, unsigned int *rsp_len,
-                     unsigned int max_rsp_len)
+                     RspBuffer *rsp)
 {
     IPMIInterface *s = ibs->parent.intf;
     IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);
@@ -994,18 +991,18 @@ static void send_msg(IPMIBmcSim *ibs,
 
     if (cmd[2] != 0) {
         /* We only handle channel 0 with no options */
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
 
     if (cmd_len < 10) {
-        rsp[2] = IPMI_CC_REQUEST_DATA_LENGTH_INVALID;
+        rsp->buffer[2] = IPMI_CC_REQUEST_DATA_LENGTH_INVALID;
         return;
     }
 
     if (cmd[3] != 0x40) {
         /* We only emulate a MC at address 0x40. */
-        rsp[2] = 0x83; /* NAK on write */
+        rsp->buffer[2] = 0x83; /* NAK on write */
         return;
     }
 
@@ -1091,11 +1088,10 @@ static void do_watchdog_reset(IPMIBmcSim *ibs)
 
 static void reset_watchdog_timer(IPMIBmcSim *ibs,
                                  uint8_t *cmd, unsigned int cmd_len,
-                                 uint8_t *rsp, unsigned int *rsp_len,
-                                 unsigned int max_rsp_len)
+                                 RspBuffer *rsp)
 {
     if (!ibs->watchdog_initialized) {
-        rsp[2] = 0x80;
+        rsp->buffer[2] = 0x80;
         return;
     }
     do_watchdog_reset(ibs);
@@ -1103,8 +1099,7 @@ static void reset_watchdog_timer(IPMIBmcSim *ibs,
 
 static void set_watchdog_timer(IPMIBmcSim *ibs,
                                uint8_t *cmd, unsigned int cmd_len,
-                               uint8_t *rsp, unsigned int *rsp_len,
-                               unsigned int max_rsp_len)
+                               RspBuffer *rsp)
 {
     IPMIInterface *s = ibs->parent.intf;
     IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);
@@ -1112,7 +1107,7 @@ static void set_watchdog_timer(IPMIBmcSim *ibs,
 
     val = cmd[2] & 0x7; /* Validate use */
     if (val == 0 || val > 5) {
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
     val = cmd[3] & 0x7; /* Validate action */
@@ -1121,22 +1116,22 @@ static void set_watchdog_timer(IPMIBmcSim *ibs,
         break;
 
     case IPMI_BMC_WATCHDOG_ACTION_RESET:
-        rsp[2] = k->do_hw_op(s, IPMI_RESET_CHASSIS, 1);
+        rsp->buffer[2] = k->do_hw_op(s, IPMI_RESET_CHASSIS, 1);
         break;
 
     case IPMI_BMC_WATCHDOG_ACTION_POWER_DOWN:
-        rsp[2] = k->do_hw_op(s, IPMI_POWEROFF_CHASSIS, 1);
+        rsp->buffer[2] = k->do_hw_op(s, IPMI_POWEROFF_CHASSIS, 1);
         break;
 
     case IPMI_BMC_WATCHDOG_ACTION_POWER_CYCLE:
-        rsp[2] = k->do_hw_op(s, IPMI_POWERCYCLE_CHASSIS, 1);
+        rsp->buffer[2] = k->do_hw_op(s, IPMI_POWERCYCLE_CHASSIS, 1);
         break;
 
     default:
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
     }
-    if (rsp[2]) {
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+    if (rsp->buffer[2]) {
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
 
@@ -1149,14 +1144,14 @@ static void set_watchdog_timer(IPMIBmcSim *ibs,
     case IPMI_BMC_WATCHDOG_PRE_NMI:
         if (!k->do_hw_op(s, IPMI_SEND_NMI, 1)) {
             /* NMI not supported. */
-            rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+            rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
             return;
         }
         break;
 
     default:
         /* We don't support PRE_SMI */
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
 
@@ -1175,60 +1170,56 @@ static void set_watchdog_timer(IPMIBmcSim *ibs,
 
 static void get_watchdog_timer(IPMIBmcSim *ibs,
                                uint8_t *cmd, unsigned int cmd_len,
-                               uint8_t *rsp, unsigned int *rsp_len,
-                               unsigned int max_rsp_len)
+                               RspBuffer *rsp)
 {
-    IPMI_ADD_RSP_DATA(ibs->watchdog_use);
-    IPMI_ADD_RSP_DATA(ibs->watchdog_action);
-    IPMI_ADD_RSP_DATA(ibs->watchdog_pretimeout);
-    IPMI_ADD_RSP_DATA(ibs->watchdog_expired);
+    rsp_buffer_push(rsp, ibs->watchdog_use);
+    rsp_buffer_push(rsp, ibs->watchdog_action);
+    rsp_buffer_push(rsp, ibs->watchdog_pretimeout);
+    rsp_buffer_push(rsp, ibs->watchdog_expired);
     if (ibs->watchdog_running) {
         long timeout;
         timeout = ((ibs->watchdog_expiry - ipmi_getmonotime() + 50000000)
                    / 100000000);
-        IPMI_ADD_RSP_DATA(timeout & 0xff);
-        IPMI_ADD_RSP_DATA((timeout >> 8) & 0xff);
+        rsp_buffer_push(rsp, timeout & 0xff);
+        rsp_buffer_push(rsp, (timeout >> 8) & 0xff);
     } else {
-        IPMI_ADD_RSP_DATA(0);
-        IPMI_ADD_RSP_DATA(0);
+        rsp_buffer_push(rsp, 0);
+        rsp_buffer_push(rsp, 0);
     }
 }
 
 static void get_sdr_rep_info(IPMIBmcSim *ibs,
                              uint8_t *cmd, unsigned int cmd_len,
-                             uint8_t *rsp, unsigned int *rsp_len,
-                             unsigned int max_rsp_len)
+                             RspBuffer *rsp)
 {
     unsigned int i;
 
-    IPMI_ADD_RSP_DATA(0x51); /* Conform to IPMI 1.5 spec */
-    IPMI_ADD_RSP_DATA(ibs->sdr.next_rec_id & 0xff);
-    IPMI_ADD_RSP_DATA((ibs->sdr.next_rec_id >> 8) & 0xff);
-    IPMI_ADD_RSP_DATA((MAX_SDR_SIZE - ibs->sdr.next_free) & 0xff);
-    IPMI_ADD_RSP_DATA(((MAX_SDR_SIZE - ibs->sdr.next_free) >> 8) & 0xff);
+    rsp_buffer_push(rsp, 0x51); /* Conform to IPMI 1.5 spec */
+    rsp_buffer_push(rsp, ibs->sdr.next_rec_id & 0xff);
+    rsp_buffer_push(rsp, (ibs->sdr.next_rec_id >> 8) & 0xff);
+    rsp_buffer_push(rsp, (MAX_SDR_SIZE - ibs->sdr.next_free) & 0xff);
+    rsp_buffer_push(rsp, ((MAX_SDR_SIZE - ibs->sdr.next_free) >> 8) & 0xff);
     for (i = 0; i < 4; i++) {
-        IPMI_ADD_RSP_DATA(ibs->sdr.last_addition[i]);
+        rsp_buffer_push(rsp, ibs->sdr.last_addition[i]);
     }
     for (i = 0; i < 4; i++) {
-        IPMI_ADD_RSP_DATA(ibs->sdr.last_clear[i]);
+        rsp_buffer_push(rsp, ibs->sdr.last_clear[i]);
     }
     /* Only modal support, reserve supported */
-    IPMI_ADD_RSP_DATA((ibs->sdr.overflow << 7) | 0x22);
+    rsp_buffer_push(rsp, (ibs->sdr.overflow << 7) | 0x22);
 }
 
 static void reserve_sdr_rep(IPMIBmcSim *ibs,
                             uint8_t *cmd, unsigned int cmd_len,
-                            uint8_t *rsp, unsigned int *rsp_len,
-                            unsigned int max_rsp_len)
+                            RspBuffer *rsp)
 {
-    IPMI_ADD_RSP_DATA(ibs->sdr.reservation & 0xff);
-    IPMI_ADD_RSP_DATA((ibs->sdr.reservation >> 8) & 0xff);
+    rsp_buffer_push(rsp, ibs->sdr.reservation & 0xff);
+    rsp_buffer_push(rsp, (ibs->sdr.reservation >> 8) & 0xff);
 }
 
 static void get_sdr(IPMIBmcSim *ibs,
                     uint8_t *cmd, unsigned int cmd_len,
-                    uint8_t *rsp, unsigned int *rsp_len,
-                    unsigned int max_rsp_len)
+                    RspBuffer *rsp)
 {
     unsigned int pos;
     uint16_t nextrec;
@@ -1240,108 +1231,103 @@ static void get_sdr(IPMIBmcSim *ibs,
     pos = 0;
     if (sdr_find_entry(&ibs->sdr, cmd[4] | (cmd[5] << 8),
                        &pos, &nextrec)) {
-        rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
+        rsp->buffer[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
         return;
     }
 
     sdrh = (struct ipmi_sdr_header *) &ibs->sdr.sdr[pos];
 
     if (cmd[6] > ipmi_sdr_length(sdrh)) {
-        rsp[2] = IPMI_CC_PARM_OUT_OF_RANGE;
+        rsp->buffer[2] = IPMI_CC_PARM_OUT_OF_RANGE;
         return;
     }
 
-    IPMI_ADD_RSP_DATA(nextrec & 0xff);
-    IPMI_ADD_RSP_DATA((nextrec >> 8) & 0xff);
+    rsp_buffer_push(rsp, nextrec & 0xff);
+    rsp_buffer_push(rsp, (nextrec >> 8) & 0xff);
 
     if (cmd[7] == 0xff) {
         cmd[7] = ipmi_sdr_length(sdrh) - cmd[6];
     }
 
-    if ((cmd[7] + *rsp_len) > max_rsp_len) {
-        rsp[2] = IPMI_CC_CANNOT_RETURN_REQ_NUM_BYTES;
+    if ((cmd[7] + rsp->len) > sizeof(rsp->buffer)) {
+        rsp->buffer[2] = IPMI_CC_CANNOT_RETURN_REQ_NUM_BYTES;
         return;
     }
-    memcpy(rsp + *rsp_len, ibs->sdr.sdr + pos + cmd[6], cmd[7]);
-    *rsp_len += cmd[7];
+
+    rsp_buffer_pushmore(rsp, ibs->sdr.sdr + pos + cmd[6], cmd[7]);
 }
 
 static void add_sdr(IPMIBmcSim *ibs,
                     uint8_t *cmd, unsigned int cmd_len,
-                    uint8_t *rsp, unsigned int *rsp_len,
-                    unsigned int max_rsp_len)
+                    RspBuffer *rsp)
 {
     uint16_t recid;
     struct ipmi_sdr_header *sdrh = (struct ipmi_sdr_header *) cmd + 2;
 
     if (sdr_add_entry(ibs, sdrh, cmd_len - 2, &recid)) {
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
-    IPMI_ADD_RSP_DATA(recid & 0xff);
-    IPMI_ADD_RSP_DATA((recid >> 8) & 0xff);
+    rsp_buffer_push(rsp, recid & 0xff);
+    rsp_buffer_push(rsp, (recid >> 8) & 0xff);
 }
 
 static void clear_sdr_rep(IPMIBmcSim *ibs,
                           uint8_t *cmd, unsigned int cmd_len,
-                          uint8_t *rsp, unsigned int *rsp_len,
-                          unsigned int max_rsp_len)
+                          RspBuffer *rsp)
 {
     IPMI_CHECK_RESERVATION(2, ibs->sdr.reservation);
     if (cmd[4] != 'C' || cmd[5] != 'L' || cmd[6] != 'R') {
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
     if (cmd[7] == 0xaa) {
         ibs->sdr.next_free = 0;
         ibs->sdr.overflow = 0;
         set_timestamp(ibs, ibs->sdr.last_clear);
-        IPMI_ADD_RSP_DATA(1); /* Erasure complete */
+        rsp_buffer_push(rsp, 1); /* Erasure complete */
         sdr_inc_reservation(&ibs->sdr);
     } else if (cmd[7] == 0) {
-        IPMI_ADD_RSP_DATA(1); /* Erasure complete */
+        rsp_buffer_push(rsp, 1); /* Erasure complete */
     } else {
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
 }
 
 static void get_sel_info(IPMIBmcSim *ibs,
                          uint8_t *cmd, unsigned int cmd_len,
-                         uint8_t *rsp, unsigned int *rsp_len,
-                         unsigned int max_rsp_len)
+                         RspBuffer *rsp)
 {
     unsigned int i, val;
 
-    IPMI_ADD_RSP_DATA(0x51); /* Conform to IPMI 1.5 */
-    IPMI_ADD_RSP_DATA(ibs->sel.next_free & 0xff);
-    IPMI_ADD_RSP_DATA((ibs->sel.next_free >> 8) & 0xff);
+    rsp_buffer_push(rsp, 0x51); /* Conform to IPMI 1.5 */
+    rsp_buffer_push(rsp, ibs->sel.next_free & 0xff);
+    rsp_buffer_push(rsp, (ibs->sel.next_free >> 8) & 0xff);
     val = (MAX_SEL_SIZE - ibs->sel.next_free) * 16;
-    IPMI_ADD_RSP_DATA(val & 0xff);
-    IPMI_ADD_RSP_DATA((val >> 8) & 0xff);
+    rsp_buffer_push(rsp, val & 0xff);
+    rsp_buffer_push(rsp, (val >> 8) & 0xff);
     for (i = 0; i < 4; i++) {
-        IPMI_ADD_RSP_DATA(ibs->sel.last_addition[i]);
+        rsp_buffer_push(rsp, ibs->sel.last_addition[i]);
     }
     for (i = 0; i < 4; i++) {
-        IPMI_ADD_RSP_DATA(ibs->sel.last_clear[i]);
+        rsp_buffer_push(rsp, ibs->sel.last_clear[i]);
     }
     /* Only support Reserve SEL */
-    IPMI_ADD_RSP_DATA((ibs->sel.overflow << 7) | 0x02);
+    rsp_buffer_push(rsp, (ibs->sel.overflow << 7) | 0x02);
 }
 
 static void reserve_sel(IPMIBmcSim *ibs,
                         uint8_t *cmd, unsigned int cmd_len,
-                        uint8_t *rsp, unsigned int *rsp_len,
-                        unsigned int max_rsp_len)
+                        RspBuffer *rsp)
 {
-    IPMI_ADD_RSP_DATA(ibs->sel.reservation & 0xff);
-    IPMI_ADD_RSP_DATA((ibs->sel.reservation >> 8) & 0xff);
+    rsp_buffer_push(rsp, ibs->sel.reservation & 0xff);
+    rsp_buffer_push(rsp, (ibs->sel.reservation >> 8) & 0xff);
 }
 
 static void get_sel_entry(IPMIBmcSim *ibs,
                           uint8_t *cmd, unsigned int cmd_len,
-                          uint8_t *rsp, unsigned int *rsp_len,
-                          unsigned int max_rsp_len)
+                          RspBuffer *rsp)
 {
     unsigned int val;
 
@@ -1349,17 +1335,17 @@ static void get_sel_entry(IPMIBmcSim *ibs,
         IPMI_CHECK_RESERVATION(2, ibs->sel.reservation);
     }
     if (ibs->sel.next_free == 0) {
-        rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
+        rsp->buffer[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
         return;
     }
     if (cmd[6] > 15) {
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
     if (cmd[7] == 0xff) {
         cmd[7] = 16;
     } else if ((cmd[7] + cmd[6]) > 16) {
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     } else {
         cmd[7] += cmd[6];
@@ -1369,79 +1355,75 @@ static void get_sel_entry(IPMIBmcSim *ibs,
     if (val == 0xffff) {
         val = ibs->sel.next_free - 1;
     } else if (val >= ibs->sel.next_free) {
-        rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
+        rsp->buffer[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
         return;
     }
     if ((val + 1) == ibs->sel.next_free) {
-        IPMI_ADD_RSP_DATA(0xff);
-        IPMI_ADD_RSP_DATA(0xff);
+        rsp_buffer_push(rsp, 0xff);
+        rsp_buffer_push(rsp, 0xff);
     } else {
-        IPMI_ADD_RSP_DATA((val + 1) & 0xff);
-        IPMI_ADD_RSP_DATA(((val + 1) >> 8) & 0xff);
+        rsp_buffer_push(rsp, (val + 1) & 0xff);
+        rsp_buffer_push(rsp, ((val + 1) >> 8) & 0xff);
     }
     for (; cmd[6] < cmd[7]; cmd[6]++) {
-        IPMI_ADD_RSP_DATA(ibs->sel.sel[val][cmd[6]]);
+        rsp_buffer_push(rsp, ibs->sel.sel[val][cmd[6]]);
     }
 }
 
 static void add_sel_entry(IPMIBmcSim *ibs,
                           uint8_t *cmd, unsigned int cmd_len,
-                          uint8_t *rsp, unsigned int *rsp_len,
-                          unsigned int max_rsp_len)
+                          RspBuffer *rsp)
 {
     if (sel_add_event(ibs, cmd + 2)) {
-        rsp[2] = IPMI_CC_OUT_OF_SPACE;
+        rsp->buffer[2] = IPMI_CC_OUT_OF_SPACE;
         return;
     }
     /* sel_add_event fills in the record number. */
-    IPMI_ADD_RSP_DATA(cmd[2]);
-    IPMI_ADD_RSP_DATA(cmd[3]);
+    rsp_buffer_push(rsp, cmd[2]);
+    rsp_buffer_push(rsp, cmd[3]);
 }
 
 static void clear_sel(IPMIBmcSim *ibs,
                       uint8_t *cmd, unsigned int cmd_len,
-                      uint8_t *rsp, unsigned int *rsp_len,
-                      unsigned int max_rsp_len)
+                      RspBuffer *rsp)
 {
     IPMI_CHECK_RESERVATION(2, ibs->sel.reservation);
     if (cmd[4] != 'C' || cmd[5] != 'L' || cmd[6] != 'R') {
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
     if (cmd[7] == 0xaa) {
         ibs->sel.next_free = 0;
         ibs->sel.overflow = 0;
         set_timestamp(ibs, ibs->sdr.last_clear);
-        IPMI_ADD_RSP_DATA(1); /* Erasure complete */
+        rsp_buffer_push(rsp, 1); /* Erasure complete */
         sel_inc_reservation(&ibs->sel);
     } else if (cmd[7] == 0) {
-        IPMI_ADD_RSP_DATA(1); /* Erasure complete */
+        rsp_buffer_push(rsp, 1); /* Erasure complete */
     } else {
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
 }
 
 static void get_sel_time(IPMIBmcSim *ibs,
                          uint8_t *cmd, unsigned int cmd_len,
-                         uint8_t *rsp, unsigned int *rsp_len,
-                         unsigned int max_rsp_len)
+                         RspBuffer *rsp)
 {
     uint32_t val;
     struct ipmi_time now;
 
     ipmi_gettime(&now);
     val = now.tv_sec + ibs->sel.time_offset;
-    IPMI_ADD_RSP_DATA(val & 0xff);
-    IPMI_ADD_RSP_DATA((val >> 8) & 0xff);
-    IPMI_ADD_RSP_DATA((val >> 16) & 0xff);
-    IPMI_ADD_RSP_DATA((val >> 24) & 0xff);
+    rsp_buffer_push(rsp, val & 0xff);
+    rsp_buffer_push(rsp, (val >> 8) & 0xff);
+    rsp_buffer_push(rsp, (val >> 16) & 0xff);
+    rsp_buffer_push(rsp, (val >> 24) & 0xff);
 }
 
 static void set_sel_time(IPMIBmcSim *ibs,
                          uint8_t *cmd, unsigned int cmd_len,
-                         uint8_t *rsp, unsigned int *rsp_len,
-                         unsigned int max_rsp_len)
+                         RspBuffer *rsp)
 {
     uint32_t val;
     struct ipmi_time now;
@@ -1453,14 +1435,13 @@ static void set_sel_time(IPMIBmcSim *ibs,
 
 static void set_sensor_evt_enable(IPMIBmcSim *ibs,
                                   uint8_t *cmd, unsigned int cmd_len,
-                                  uint8_t *rsp, unsigned int *rsp_len,
-                                  unsigned int max_rsp_len)
+                                  RspBuffer *rsp)
 {
     IPMISensor *sens;
 
     if ((cmd[2] >= MAX_SENSORS) ||
             !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
-        rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
+        rsp->buffer[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
         return;
     }
     sens = ibs->sensors + cmd[2];
@@ -1496,7 +1477,7 @@ static void set_sensor_evt_enable(IPMIBmcSim *ibs,
         }
         break;
     case 3:
-        rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
+        rsp->buffer[2] = IPMI_CC_INVALID_DATA_FIELD;
         return;
     }
     IPMI_SENSOR_SET_RET_STATUS(sens, cmd[3]);
@@ -1504,34 +1485,32 @@ static void set_sensor_evt_enable(IPMIBmcSim *ibs,
 
 static void get_sensor_evt_enable(IPMIBmcSim *ibs,
                                   uint8_t *cmd, unsigned int cmd_len,
-                                  uint8_t *rsp, unsigned int *rsp_len,
-                                  unsigned int max_rsp_len)
+                                  RspBuffer *rsp)
 {
     IPMISensor *sens;
 
     if ((cmd[2] >= MAX_SENSORS) ||
         !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
-        rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
+        rsp->buffer[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
         return;
     }
     sens = ibs->sensors + cmd[2];
-    IPMI_ADD_RSP_DATA(IPMI_SENSOR_GET_RET_STATUS(sens));
-    IPMI_ADD_RSP_DATA(sens->assert_enable & 0xff);
-    IPMI_ADD_RSP_DATA((sens->assert_enable >> 8) & 0xff);
-    IPMI_ADD_RSP_DATA(sens->deassert_enable & 0xff);
-    IPMI_ADD_RSP_DATA((sens->deassert_enable >> 8) & 0xff);
+    rsp_buffer_push(rsp, IPMI_SENSOR_GET_RET_STATUS(sens));
+    rsp_buffer_push(rsp, sens->assert_enable & 0xff);
+    rsp_buffer_push(rsp, (sens->assert_enable >> 8) & 0xff);
+    rsp_buffer_push(rsp, sens->deassert_enable & 0xff);
+    rsp_buffer_push(rsp, (sens->deassert_enable >> 8) & 0xff);
 }
 
 static void rearm_sensor_evts(IPMIBmcSim *ibs,
                               uint8_t *cmd, unsigned int cmd_len,
-                              uint8_t *rsp, unsigned int *rsp_len,
-                              unsigned int max_rsp_len)
+                              RspBuffer *rsp)
 {
     IPMISensor *sens;
 
     if ((cmd[2] >= MAX_SENSORS) ||
         !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
-        rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
+        rsp->buffer[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
         return;
     }
     sens = ibs->sensors + cmd[2];
@@ -1545,57 +1524,54 @@ static void rearm_sensor_evts(IPMIBmcSim *ibs,
 
 static void get_sensor_evt_status(IPMIBmcSim *ibs,
                                   uint8_t *cmd, unsigned int cmd_len,
-                                  uint8_t *rsp, unsigned int *rsp_len,
-                                  unsigned int max_rsp_len)
+                                  RspBuffer *rsp)
 {
     IPMISensor *sens;
 
     if ((cmd[2] >= MAX_SENSORS) ||
         !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
-        rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
+        rsp->buffer[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
         return;
     }
     sens = ibs->sensors + cmd[2];
-    IPMI_ADD_RSP_DATA(sens->reading);
-    IPMI_ADD_RSP_DATA(IPMI_SENSOR_GET_RET_STATUS(sens));
-    IPMI_ADD_RSP_DATA(sens->assert_states & 0xff);
-    IPMI_ADD_RSP_DATA((sens->assert_states >> 8) & 0xff);
-    IPMI_ADD_RSP_DATA(sens->deassert_states & 0xff);
-    IPMI_ADD_RSP_DATA((sens->deassert_states >> 8) & 0xff);
+    rsp_buffer_push(rsp, sens->reading);
+    rsp_buffer_push(rsp, IPMI_SENSOR_GET_RET_STATUS(sens));
+    rsp_buffer_push(rsp, sens->assert_states & 0xff);
+    rsp_buffer_push(rsp, (sens->assert_states >> 8) & 0xff);
+    rsp_buffer_push(rsp, sens->deassert_states & 0xff);
+    rsp_buffer_push(rsp, (sens->deassert_states >> 8) & 0xff);
 }
 
 static void get_sensor_reading(IPMIBmcSim *ibs,
                                uint8_t *cmd, unsigned int cmd_len,
-                               uint8_t *rsp, unsigned int *rsp_len,
-                               unsigned int max_rsp_len)
+                               RspBuffer *rsp)
 {
     IPMISensor *sens;
 
     if ((cmd[2] >= MAX_SENSORS) ||
             !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
-        rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
+        rsp->buffer[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
         return;
     }
     sens = ibs->sensors + cmd[2];
-    IPMI_ADD_RSP_DATA(sens->reading);
-    IPMI_ADD_RSP_DATA(IPMI_SENSOR_GET_RET_STATUS(sens));
-    IPMI_ADD_RSP_DATA(sens->states & 0xff);
+    rsp_buffer_push(rsp, sens->reading);
+    rsp_buffer_push(rsp, IPMI_SENSOR_GET_RET_STATUS(sens));
+    rsp_buffer_push(rsp, sens->states & 0xff);
     if (IPMI_SENSOR_IS_DISCRETE(sens)) {
-        IPMI_ADD_RSP_DATA((sens->states >> 8) & 0xff);
+        rsp_buffer_push(rsp, (sens->states >> 8) & 0xff);
     }
 }
 
 static void set_sensor_type(IPMIBmcSim *ibs,
-                               uint8_t *cmd, unsigned int cmd_len,
-                               uint8_t *rsp, unsigned int *rsp_len,
-                               unsigned int max_rsp_len)
+                            uint8_t *cmd, unsigned int cmd_len,
+                            RspBuffer *rsp)
 {
     IPMISensor *sens;
 
 
     if ((cmd[2] >= MAX_SENSORS) ||
             !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
-        rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
+        rsp->buffer[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
         return;
     }
     sens = ibs->sensors + cmd[2];
@@ -1604,21 +1580,20 @@ static void set_sensor_type(IPMIBmcSim *ibs,
 }
 
 static void get_sensor_type(IPMIBmcSim *ibs,
-                               uint8_t *cmd, unsigned int cmd_len,
-                               uint8_t *rsp, unsigned int *rsp_len,
-                               unsigned int max_rsp_len)
+                            uint8_t *cmd, unsigned int cmd_len,
+                            RspBuffer *rsp)
 {
     IPMISensor *sens;
 
 
     if ((cmd[2] >= MAX_SENSORS) ||
             !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
-        rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
+        rsp->buffer[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
         return;
     }
     sens = ibs->sensors + cmd[2];
-    IPMI_ADD_RSP_DATA(sens->sensor_type);
-    IPMI_ADD_RSP_DATA(sens->evt_reading_type_code);
+    rsp_buffer_push(rsp, sens->sensor_type);
+    rsp_buffer_push(rsp, sens->evt_reading_type_code);
 }
 
 
