From: Sjur Brændeland <sjur.brandeland@xxxxxxxxxxxxxx>
Add the feature VIRTIO_CONSOLE_F_NO_HVC. With this bit set
only port-devices are created. The console port and
port control virtio-queues are not created.
The console port is not suited for communicating
to a remote processor because of it's blocking behavior.
But the port-device supports efficient non-blocking IO
to a remote processor.
Signed-off-by: Sjur Brændeland <sjur.brandeland@xxxxxxxxxxxxxx>
cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
cc: Amit Shah <amit.shah@xxxxxxxxxx>
cc: Ohad Ben-Cohen <ohad@xxxxxxxxxx>
cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
cc: linux-kernel@xxxxxxxxxxxxxxx
---
drivers/char/virtio_console.c | 6 +++++-
include/linux/virtio_console.h | 1 +
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 469c05f..7408c00 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1244,10 +1244,13 @@ static int add_port(struct ports_device *portdev, u32 id)
goto free_device;
}
+ /* Don't initialize the port_console if F_NO_HVC is set*/
+ if (virtio_has_feature(port->portdev->vdev, VIRTIO_CONSOLE_F_NO_HVC))
+ port->host_connected = true;
/*
* If we're not using multiport support, this has to be a console port
*/
- if (!use_multiport(port->portdev)) {
+ else if (!use_multiport(port->portdev)) {
err = init_port_console(port);
if (err)
goto free_inbufs;
@@ -1896,6 +1899,7 @@ static unsigned int features[] = {
#if VIRTIO_CONSOLE_HAS_DMA
VIRTIO_CONSOLE_F_DMA_MEM,
#endif
+ VIRTIO_CONSOLE_F_NO_HVC,
};
diff --git a/include/linux/virtio_console.h b/include/linux/virtio_console.h
index b27f7fa..a7c8974 100644
--- a/include/linux/virtio_console.h
+++ b/include/linux/virtio_console.h
@@ -39,6 +39,7 @@
#define VIRTIO_CONSOLE_F_SIZE 0 /* Does host provide console size? */
#define VIRTIO_CONSOLE_F_MULTIPORT 1 /* Does host provide multiple ports? */
#define VIRTIO_CONSOLE_F_DMA_MEM 2 /* Use DMA memory in vrings */
+#define VIRTIO_CONSOLE_F_NO_HVC 3 /* Disable use of HVC */
#define VIRTIO_CONSOLE_BAD_ID (~(u32)0)
--
1.7.9.5
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