In the source code of qemu or linux, there is a check for the virtio version
/* Check device version */
priv->version = readl(priv->base + VIRTIO_MMIO_VERSION);
if (priv->version < 1 || priv->version > 2) {
debug("(%s): version %d not supported!\n",
udev->name, priv->version);
return 0;
}
/* Check device ID */
uc_priv->device = readl(priv->base + VIRTIO_MMIO_DEVICE_ID);
if (uc_priv->device == 0) {
/*
* virtio-mmio device with an ID 0 is a (dummy) placeholder
* with no function. End probing now with no error reported.
*/
return 0;
}
Signed-off-by: wangmingrong1 <wangmingrong1@xiaomi.com>
eed302b8bb