diff --git a/os/sb/host/sb.h b/os/sb/host/sb.h
index 67634b3cf..9f98d3f32 100644
--- a/os/sb/host/sb.h
+++ b/os/sb/host/sb.h
@@ -32,6 +32,8 @@
 #include "vfs.h"
 #include "errcodes.h"
 
+#include "sbhdr.h"
+
 /*===========================================================================*/
 /* Module constants.                                                         */
 /*===========================================================================*/
@@ -154,6 +156,11 @@
 /* Module data structures and types.                                         */
 /*===========================================================================*/
 
+/**
+ * @brief   Type of a mask of Virtual IRQs.
+ */
+typedef uint32_t sb_vrqmask_t;
+
 /**
  * @brief   Type of a sandbox manager global structure.
  */
@@ -244,6 +251,10 @@ typedef struct {
    * @brief   Thread running in the sandbox.
    */
   thread_t                      *tp;
+  /**
+   * @brief   Pointer to the image header.
+   */
+  const sb_header_t             *sbhp;
 #if (CH_CFG_USE_MESSAGES == TRUE) || defined(__DOXYGEN__)
   /**
    * @brief   Thread sending a message to the sandbox.
@@ -256,6 +267,20 @@ typedef struct {
    */
   event_source_t                es;
 #endif
+#if (SB_CFG_ENABLE_VRQ == TRUE) || defined(__DOXYGEN__)
+  /**
+   * @brief   Global virtual IRQ status register.
+   */
+  uint32_t                      vrq_isr;
+  /**
+   * @brief   Mask of enabled virtual IRQ flags.
+   */
+  sb_vrqmask_t                  vrq_enmask;
+  /**
+   * @brief   Mask of pending virtual IRQ flags.
+   */
+  sb_vrqmask_t                  vrq_wtmask;
+#endif
 #if (SB_CFG_ENABLE_VFS == TRUE) || defined(__DOXYGEN__)
   /**
    * @brief   VFS bindings for Posix API.
@@ -289,7 +314,6 @@ extern "C" {
 #include "sbelf.h"
 #include "sbposix.h"
 #include "sbapi.h"
-#include "sbhdr.h"
 #include "sbhost.h"
 
 #endif /* SBHOST_H */
diff --git a/os/sb/host/sbapi.c b/os/sb/host/sbapi.c
index 899579af6..c639351f2 100644
--- a/os/sb/host/sbapi.c
+++ b/os/sb/host/sbapi.c
@@ -71,6 +71,18 @@ static void sb_api_loadelf(struct port_extctx *ectxp);
 #define SB_SVC12_HANDLER        sb_api_loadelf
 /** @} */
 
+/**
+ * @name    Standard API handlers
+ * @{
+ */
+#if (SB_CFG_ENABLE_VRQ == TRUE) || defined(__DOXYGEN__)
+#define SB_SVC252_HANDLER       sb_vrq_disable
+#define SB_SVC253_HANDLER       sb_vrq_enable
+#define SB_SVC254_HANDLER       sb_vrq_getisr
+#define SB_SVC255_HANDLER       sb_vrq_return
+#endif
+/** @} */
+
 #define __SVC(x) asm volatile ("svc " #x)
 
 /*
@@ -958,7 +970,6 @@ static thread_t *sb_msg_wait_timeout_s(sysinterval_t timeout) {
   return tp;
 }
 
-
 static void sb_cleanup(void) {
 #if SB_CFG_ENABLE_VFS == TRUE
   sb_class_t *sbp = (sb_class_t *)chThdGetSelfX()->ctx.syscall.p;
diff --git a/os/sb/host/sbapi.h b/os/sb/host/sbapi.h
index 0939208fb..3a3d5b137 100644
--- a/os/sb/host/sbapi.h
+++ b/os/sb/host/sbapi.h
@@ -60,7 +60,7 @@ typedef void (*port_syscall_t)(struct port_extctx *ectx);
 #ifdef __cplusplus
 extern "C" {
 #endif
-
+  void __sb_abort(msg_t msg);
 #ifdef __cplusplus
 }
 #endif
diff --git a/os/sb/host/sbhost.c b/os/sb/host/sbhost.c
index 6aa2f0c2b..6d96a2114 100644
--- a/os/sb/host/sbhost.c
+++ b/os/sb/host/sbhost.c
@@ -25,6 +25,8 @@
  * @{
  */
 
+#include <string.h>
+
 #include "ch.h"
 #include "sb.h"
 
@@ -194,14 +196,8 @@ size_t sb_check_strings_array(sb_class_t *sbp, const char *pp[], size_t max) {
  */
 void sbObjectInit(sb_class_t *sbp, const sb_config_t *config) {
 
+  memset((void *)sbp, 0, sizeof (sb_class_t));
   sbp->config = config;
-  sbp->tp     = NULL;
-#if CH_CFG_USE_MESSAGES == TRUE
-  sbp->msg_tp = NULL;
-#endif
-#if CH_CFG_USE_EVENTS == TRUE
-  chEvtObjectInit(&sbp->es);
-#endif
 }
 
 /**
@@ -221,29 +217,28 @@ thread_t *sbStartThread(sb_class_t *sbp, const char *name,
                         void *wsp, size_t size, tprio_t prio,
                         const char *argv[], const char *envp[]) {
   thread_t *utp;
-  const sb_header_t *sbhp;
   const sb_config_t *config = sbp->config;
   void *usp, *uargv, *uenvp;
   size_t envsize, argsize, parsize;
   int uargc, uenvc;
 
   /* Header location.*/
-  sbhp = (const sb_header_t *)(void *)config->regions[config->code_region].area.base;
+  sbp->sbhp = (const sb_header_t *)(void *)config->regions[config->code_region].area.base;
 
   /* Checking header magic numbers.*/
-  if ((sbhp->hdr_magic1 != SB_HDR_MAGIC1) ||
-      (sbhp->hdr_magic2 != SB_HDR_MAGIC2)) {
+  if ((sbp->sbhp->hdr_magic1 != SB_HDR_MAGIC1) ||
+      (sbp->sbhp->hdr_magic2 != SB_HDR_MAGIC2)) {
     return NULL;
   }
 
   /* Checking header size and alignment.*/
-  if (sbhp->hdr_size != sizeof (sb_header_t)) {
+  if (sbp->sbhp->hdr_size != sizeof (sb_header_t)) {
     return NULL;
   }
 
   /* Checking header entry point.*/
   if (!chMemIsSpaceWithinX(&config->regions[config->code_region].area,
-                           (const void *)sbhp->hdr_entry,
+                           (const void *)sbp->sbhp->hdr_entry,
                            (size_t)2)) {
     return NULL;
   }
@@ -290,7 +285,7 @@ thread_t *sbStartThread(sb_class_t *sbp, const char *name,
     .wbase      = (stkalign_t *)wsp,
     .wend       = (stkalign_t *)wsp + (size / sizeof (stkalign_t)),
     .prio       = prio,
-    .u_pc       = sbhp->hdr_entry,
+    .u_pc       = sbp->sbhp->hdr_entry,
     .u_psp      = (uint32_t)usp,
     .arg        = (void *)sbp
   };
@@ -303,7 +298,7 @@ thread_t *sbStartThread(sb_class_t *sbp, const char *name,
   utp = chThdCreateUnprivileged(&utd);
 
   /* For messages exchange.*/
-  sbp->tp      = utp;
+  sbp->tp = utp;
 
   return utp;
 }
@@ -345,7 +340,6 @@ msg_t sbExec(sb_class_t *sbp, const char *pathname,
              const char *argv[], const char *envp[]) {
   const sb_config_t *config = sbp->config;
   memory_area_t ma = config->regions[0].area;
-  const sb_header_t *sbhp;
   msg_t ret;
   void *usp, *uargv, *uenvp;
   size_t envsize, argsize, parsize;
@@ -396,21 +390,21 @@ msg_t sbExec(sb_class_t *sbp, const char *pathname,
   CH_RETURN_ON_ERROR(ret);
 
   /* Header location.*/
-  sbhp = (const sb_header_t *)(void *)ma.base;
+  sbp->sbhp = (const sb_header_t *)(void *)ma.base;
 
   /* Checking header magic numbers.*/
-  if ((sbhp->hdr_magic1 != SB_HDR_MAGIC1) ||
-      (sbhp->hdr_magic2 != SB_HDR_MAGIC2)) {
+  if ((sbp->sbhp->hdr_magic1 != SB_HDR_MAGIC1) ||
+      (sbp->sbhp->hdr_magic2 != SB_HDR_MAGIC2)) {
     return CH_RET_ENOEXEC;
   }
 
   /* Checking header size.*/
-  if (sbhp->hdr_size != sizeof (sb_header_t)) {
+  if (sbp->sbhp->hdr_size != sizeof (sb_header_t)) {
     return CH_RET_ENOEXEC;
   }
 
   /* Checking header entry point.*/
-  if (!chMemIsSpaceWithinX(&ma, (const void *)sbhp->hdr_entry, (size_t)2)) {
+  if (!chMemIsSpaceWithinX(&ma, (const void *)sbp->sbhp->hdr_entry, (size_t)2)) {
     return CH_RET_EFAULT;
   }
 
@@ -420,7 +414,7 @@ msg_t sbExec(sb_class_t *sbp, const char *pathname,
     .wbase      = (stkalign_t *)wsp,
     .wend       = (stkalign_t *)wsp + (size / sizeof (stkalign_t)),
     .prio       = prio,
-    .u_pc       = sbhp->hdr_entry,
+    .u_pc       = sbp->sbhp->hdr_entry,
     .u_psp      = (uint32_t)usp,
     .arg        = (void *)sbp
   };
diff --git a/os/sb/host/sbvrq.c b/os/sb/host/sbvrq.c
index 0c384616d..33031b739 100644
--- a/os/sb/host/sbvrq.c
+++ b/os/sb/host/sbvrq.c
@@ -51,55 +51,157 @@
 /* Module local functions.                                                   */
 /*===========================================================================*/
 
+__STATIC_FORCEINLINE void vfq_makectx(sb_class_t *sbp,
+                                      struct port_extctx *ectxp,
+                                      uint32_t active_mask) {
+  uint32_t irqn = __CLZ(active_mask);
+  sbp->vrq_wtmask &= ~(1U << irqn);
+
+  /* Building the return context.*/
+  ectxp->r0     = irqn;
+  ectxp->pc     = sbp->sbhp->hdr_vfq; /* TODO validate or let it eventually crash? */
+  ectxp->xpsr   = 0x01000000U;
+#if CORTEX_USE_FPU == TRUE
+  ectxp->fpscr  = FPU->FPDSCR;
+#endif
+}
+
 /*===========================================================================*/
 /* Module exported functions.                                                */
 /*===========================================================================*/
 
 /**
- * @brief   Activates VRQs on the specified sandbox.
+ * @brief   Triggers VRQs on the specified sandbox.
+ * @note    This function must be called from IRQ context because
+ *          it manipulates exception stack frames.
  *
  * @param[in] sbp       pointer to a @p sb_class_t structure
  * @param[in] vmask     mask of VRQs to be activated
  * @return              The operation status.
  * @retval false        if the activation has succeeded.
  * @retval true         in case of sandbox stack overflow.
+ *
+ * @special
  */
-bool sbVRQSignalMaskI(sb_class_t *sbp, sb_vrqmask_t vmask) {
+bool sbVRQTriggerFromISR(sb_class_t *sbp, sb_vrqmask_t vmask) {
   struct port_extctx *ectxp;
-  const sb_header_t *sbhp;
 
-  /* This IRQ could have preempted the sandbox itself or some other thread,
-     handling is different.*/
-  if (sbp->tp->state == CH_STATE_CURRENT) {
-    /* Sandbox case, getting the current exception frame.*/
-    ectxp = (struct port_extctx *)__get_PSP() - 1;
+  chSysLockFromISR();
 
-    /* Checking if the new frame is within the sandbox else failure.*/
-    if (!sb_is_valid_write_range(sbp,
-                                 (void *)ectxp,
-                                 sizeof (struct port_extctx))) {
-      return true;
+  /* Adding VRQ mask to the pending mask.*/
+  sbp->vrq_wtmask |= vmask;
+
+  /* Triggering the VRQ if required.*/
+  if (sbp->vrq_isr == 0U) {
+    sb_vrqmask_t active_mask = sbp->vrq_wtmask & sbp->vrq_enmask;
+
+    if (active_mask != 0U) {
+
+      /* This IRQ could have preempted the sandbox itself or some other thread,
+         handling is different.*/
+      if (sbp->tp->state == CH_STATE_CURRENT) {
+        /* Sandbox case, getting the current exception frame.*/
+        ectxp = (struct port_extctx *)__get_PSP() - 1;
+
+        /* Checking if the new frame is within the sandbox else failure.*/
+        if (!sb_is_valid_write_range(sbp,
+                                     (void *)ectxp,
+                                     sizeof (struct port_extctx))) {
+          chSysUnlockFromISR();
+
+          return true;
+        }
+      }
+      else {
+        ectxp = sbp->tp->ctx.sp - 1;
+
+        /* Checking if the new frame is within the sandbox else failure.*/
+        if (!sb_is_valid_write_range(sbp,
+                                     (void *)ectxp,
+                                     sizeof (struct port_extctx))) {
+          chSysUnlockFromISR();
+
+          return true;
+        }
+
+        /* Preventing leakage of information, clearing all register values, those
+           would come from outside the sandbox.*/
+        memset((void *)ectxp, 0, sizeof (struct port_extctx));
+      }
+
+      /* Building the return context.*/
+      vfq_makectx(sbp, ectxp, active_mask);
+    }
+  }
+
+  chSysUnlockFromISR();
+
+  return false;
+}
+
+void sb_vrq_disable(struct port_extctx *ectxp) {
+  sb_class_t *sbp = (sb_class_t *)chThdGetSelfX()->ctx.syscall.p;
+
+  ectxp->r0 = sbp->vrq_isr;
+  sbp->vrq_isr |= SB_VRQ_ISR_DISABLED;
+}
+
+void sb_vrq_enable(struct port_extctx *ectxp) {
+  sb_class_t *sbp = (sb_class_t *)chThdGetSelfX()->ctx.syscall.p;
+
+  ectxp->r0 = sbp->vrq_isr;
+  sbp->vrq_isr &= ~SB_VRQ_ISR_DISABLED;
+
+  /* Re-triggering the VRQ if required.*/
+  if (sbp->vrq_isr == 0U) {
+    sb_vrqmask_t active_mask = sbp->vrq_wtmask & sbp->vrq_enmask;
+
+    if (active_mask != 0U) {
+      /* Creating a context for return.*/
+      ectxp--;
+
+      /* Checking if the new frame is within the sandbox else failure.*/
+      if (!sb_is_valid_write_range(sbp,
+                                   (void *)ectxp,
+                                   sizeof (struct port_extctx))) {
+        __sb_abort(CH_RET_EFAULT);
+      }
+
+      /* Building the return context.*/
+      vfq_makectx(sbp, ectxp, active_mask);
+    }
+  }
+}
+
+void sb_vrq_getisr(struct port_extctx *ectxp) {
+  sb_class_t *sbp = (sb_class_t *)chThdGetSelfX()->ctx.syscall.p;
+
+  ectxp->r0 = sbp->vrq_isr;
+}
+
+void sb_vrq_return(struct port_extctx *ectxp) {
+  sb_class_t *sbp = (sb_class_t *)chThdGetSelfX()->ctx.syscall.p;
+
+  if (((sbp->vrq_isr & SB_VRQ_ISR_IRQMODE) == 0U)) {
+    __sb_abort(CH_RET_EFAULT);
+  }
+
+  /* Re-triggering the VRQ if required.*/
+  if (sbp->vrq_isr == 0U) {
+    sb_vrqmask_t active_mask = sbp->vrq_wtmask & sbp->vrq_enmask;
+
+    if (active_mask != 0U) {
+      /* Building the return context, reusing the current context structure.*/
+      vfq_makectx(sbp, ectxp, active_mask);
     }
   }
   else {
-    ectxp = sbp->tp->ctx.sp - 1;
+    /* Ending IRQ mode.*/
+    sbp->vrq_isr &= ~SB_VRQ_ISR_IRQMODE;
 
-    /* Checking if the new frame is within the sandbox else failure.*/
-    if (!sb_is_valid_write_range(sbp,
-                                 (void *)ectxp,
-                                 sizeof (struct port_extctx))) {
-      return true;
-    }
-
-    /* Preventing leakage of information, clearing all register values, those
-       would come from outside the sandbox.*/
-    memset((void *)ectxp, 0, sizeof (struct port_extctx));
+    /* Discarding the return current context, returning on the previous one.*/
+    ectxp++;
   }
-
-  /* Header location.*/
-  sbhp = (const sb_header_t *)(void *)sbp->config->regions[sbp->config->code_region].area.base;
-
-  return false;
 }
 
 #endif /* SB_CFG_ENABLE_VRQ == TRUE */
diff --git a/os/sb/host/sbvrq.h b/os/sb/host/sbvrq.h
index 4dc73e4ad..2d4d6d16d 100644
--- a/os/sb/host/sbvrq.h
+++ b/os/sb/host/sbvrq.h
@@ -34,6 +34,14 @@
 /* Module constants.                                                         */
 /*===========================================================================*/
 
+/**
+ * @name    Virtual ISR register bit definitions
+ * @{
+ */
+#define SB_VRQ_ISR_DISABLED     1U
+#define SB_VRQ_ISR_IRQMODE      2U
+/** @} */
+
 /*===========================================================================*/
 /* Module pre-compile time settings.                                         */
 /*===========================================================================*/
@@ -46,11 +54,6 @@
 /* Module data structures and types.                                         */
 /*===========================================================================*/
 
-/**
- * @brief   Type of a mask of Virtual IRQs.
- */
-typedef uint32_t sb_vrqmask_t;
-
 /*===========================================================================*/
 /* Module macros.                                                            */
 /*===========================================================================*/
@@ -62,7 +65,11 @@ typedef uint32_t sb_vrqmask_t;
 #ifdef __cplusplus
 extern "C" {
 #endif
-  bool sbVRQSignalMaskI(sb_class_t *sbp, sb_vrqmask_t vmask);
+  bool sbVRQTriggerFromISR(sb_class_t *sbp, sb_vrqmask_t vmask);
+  void sb_vrq_disable(struct port_extctx *ectxp);
+  void sb_vrq_enable(struct port_extctx *ectxp);
+  void sb_vrq_getisr(struct port_extctx *ectxp);
+  void sb_vrq_return(struct port_extctx *ectxp);
 #ifdef __cplusplus
 }
 #endif