device or SD card) or type of boot device (e.g. USB disk). The parameters to
the func macro (passed in by the internal implementation of the header) are:
-- Upper-case disk type (MMC, SATA, SCSI, IDE, USB, DHCP, PXE).
+- Upper-case disk type (MMC, SATA, SCSI, IDE, USB, DHCP, PXE, VIRTIO).
- Lower-case disk type (same options as above).
- ID of the specific disk (MMC only) or ignored for other types.
* scsi
* ide
* usb
+ * virtio
Other *boot* variables than the ones defined above are only for internal use
of the boot environment and are not guaranteed to exist or work in the same