| .. _ivshmem_driver: |
| |
| Inter-VM Shared Memory |
| ###################### |
| |
| .. contents:: |
| :local: |
| :depth: 2 |
| |
| Overview |
| ******** |
| |
| As Zephyr is enabled to run as a guest OS on Qemu and |
| `ACRN <https://projectacrn.github.io/latest/tutorials/using_zephyr_as_uos.html>`_ |
| it might be necessary to make VMs aware of each other, or aware of the host. |
| This is made possible by exposing a shared memory among parties via a feature |
| called ivshmem, which stands for inter-VM Shared Memory. |
| |
| The Two types are supported: a plain shared memory (ivshmem-plain) or a shared |
| memory with the ability for a VM to generate an interruption on another, and |
| thus to be interrupted as well itself (ivshmem-doorbell). |
| |
| Please refer to the official `Qemu ivshmem documentation |
| <https://www.qemu.org/docs/master/system/devices/ivshmem.html>`_ for more information. |
| |
| Support |
| ******* |
| |
| Zephyr supports both version: plain and doorbell. Ivshmem driver can be build |
| by enabling :kconfig:option:`CONFIG_IVSHMEM`. By default, this will expose the plain |
| version. :kconfig:option:`CONFIG_IVSHMEM_DOORBELL` needs to be enabled to get the |
| doorbell version. |
| |
| Because the doorbell version uses MSI-X vectors to support notification vectors, |
| the :kconfig:option:`CONFIG_IVSHMEM_MSI_X_VECTORS` has to be tweaked to the amount of |
| vectors that will be needed. |
| |
| Note that a tiny shell module can be exposed to test the ivshmem feature by |
| enabling :kconfig:option:`CONFIG_IVSHMEM_SHELL`. |
| |
| API Reference |
| ************* |
| |
| .. doxygengroup:: ivshmem |
