Create an Interrupt object from a Messaged-Signaled Interrupt (MSI) allocation.


#include <zircon/syscalls.h>

zx_status_t zx_msi_create(zx_handle_t handle,
                          uint32_t options,
                          uint32_t msi_id,
                          zx_handle_t vmo,
                          size_t vmo_offset,
                          zx_handle_t* out_interrupt);


zx_msi_create() creates an Interrupt object corresponding to a given MSI within an MSI allocation handle created by zx_msi_allocate(). This object can be used with the various interrupt syscalls in the same manner one would use an Interrupt object returned by zx_interrupt_create(). Only one Interrupt object can be created per msi_id at a time, but the same vmo and vmo_offset is usable for multiple MSIs created from the same MSI allocation object. This allows for a holder of the root resource to both allocate vectors and MSIs from the system, as well as create Interrupt objects corresponding to those vectors for use in device drivers.

vmo should be a handle referring to a physical vmo (created through *zx_vmo_create_physical()) with the cache policy *ZX_CACHE_POLICY_UNCACHED_DEVICE. For test purposes a contiguous *zx_vmo_create_contiguous() vmo can be used.

msi_id corresponds to the vector in a given MSI allocation to create an Interrupt object for. msi_id must be be between 0 and the allocation size minus 1, inclusive.

vmo_offset corresponds to the offset within vmo where the MSI capability structure begins. Details of this structure can be found in the PCI Local Bus Specification v3.0, section 6.8.

options should be 0.


handle must be of type ZX_OBJ_TYPE_MSI.

vmo must be of type ZX_OBJ_TYPE_VMO.

vmo must have ZX_RIGHT_MAP.

Return value

zx_msi_create() returns ZX_OK on success. In the event of failure, a negative error value is returned.


ZX_ERR_BAD_HANDLE the handle is invalid.

ZX_ERR_WRONG_TYPE handle is not the appropriate type.

ZX_ERR_INVALID_ARGS msi_id is not a valid MSI id within the allocation referred to by handle, vmo is not the size of a ZX_PAGE_SIZE, vmo is not physical or contiguous, vmo does not have cache policy set to ZX_CACHE_POLICY_UNCACHED_DEVICE, vmo does not appear to contain a supported MSI/MSI-X capability, vmo_offset is out of bounds of vmo, vmo_offset is invalid for the type of capability structure found, options is not 0, or out_interrupt is NULL.

ZX_ERR_ALREADY_BOUND An Interrupt object corresponding to msi_id already *exists.

See also