MSI-X Interrupts

MSI-X interrupts are enhanced versions of MSI interrupts that have the same features as MSI interrupts with the following key differences:

• A maximum of 2048 MSI-X interrupt vectors are supported per device.

• Address and data entries are unique per interrupt vector.

• MSI-X supports per function masking and per vector masking.

With MSI-X interrupts, an unallocated interrupt vector of a device can use a previously added or initialized MSI-X interrupt vector to share the same vector address, vector data, interrupt handler, and handler arguments. Use the ddi_intr_dup_handler(9F) function to alias the resources provided by the Oracle Solaris OS to the unallocated interrupt vectors on an associated device. For example, if 2 MSI-X interrupts are allocated to a driver and 32 interrupts are supported on the device, then the driver can use ddi_intr_dup_handler() to alias the 2 interrupts it received to the 30 additional interrupts on the device.

The ddi_intr_dup_handler() function can duplicate interrupts that were added with ddi_intr_add_handler(9F) or initialized with ddi_intr_enable(9F).

A duplicated interrupt is disabled initially. Use ddi_intr_enable() to enable the duplicated interrupt. You cannot remove the original MSI-X interrupt handler until all duplicated interrupt handlers that are associated with this original interrupt handler are removed. To remove a duplicated interrupt handler, first call ddi_intr_disable(9F), and then call ddi_intr_free(9F). When all duplicated interrupt handlers that are associated with this original interrupt handler are removed, then you can use ddi_intr_remove_handler(9F) to remove the original MSI-X interrupt handler. See the ddi_intr_dup_handler(9F) man page for examples.