Virtio-serial API: Difference between revisions
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There's an in-qemu host API exposed by the virtio-serial code. The following is true for the in-qemu API for qemu version 0.13 and for the qemu version found in Red Hat Enterprise Linux 6.0, straight from [http://git.qemu.org/qemu.git/tree/hw/virtio-serial.h?h=stable-0.13 hw/virtio-serial.h]: | There's an in-qemu host API exposed by the virtio-serial code. The following is true for the in-qemu API for qemu version 0.13 and for the qemu version found in Red Hat Enterprise Linux 6.0, straight from [http://git.qemu.org/qemu.git/tree/hw/virtio-serial.h?h=stable-0.13 hw/virtio-serial.h]: | ||
{| | |||
| <code> | |||
/* | /* | ||
* Individual ports/apps should call this function to register the port | * Individual ports/apps should call this function to register the port | ||
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*/ | */ | ||
void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle); | void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle); | ||
</code> | |||
|} | |||
In addition to this, the '''VirtIOSerialPortInfo''' struct has a function pointer for a callback to be called when guest writes some data to the port: | |||
{| | |||
|<code> | |||
/* | |||
* Guest wrote some data to the port. This data is handed over to | |||
* the app via this callback. The app is supposed to consume all | |||
* the data that is presented to it. | |||
*/ | |||
void (*have_data)(VirtIOSerialPort *port, const uint8_t *buf, size_t len); | |||
</code> | |||
|} | |||
For an example use of this API, see [http://git.qemu.org/qemu.git/tree/hw/virtio-console.c?h=stable-0.13 hw/virtio-console.c] | For an example use of this API, see [http://git.qemu.org/qemu.git/tree/hw/virtio-console.c?h=stable-0.13 hw/virtio-console.c] |
Revision as of 06:04, 2 September 2010
Guest API
Function | Linux guest | Windows guest |
---|---|---|
Port discovery | symlinks from /dev/virtio-port/<portname> to /dev/vportNpn | |
Opening port | open(2). Returns >= 0 on success. Only one open allowed at a time for a port. | |
Reading | read(2). Blocking as well as non-blocking reads available. Return 0 if host is not connected. Block or -EINTR otherwise. Return -ENODEV if port or device get hot-unplugged | |
Writing | write(2). Blocking as well as non-blocking. If host is not connected, write blocks or returns -EINTR. Return -ENODEV if port or device get hot-unplugged. | |
Poll | poll(). POLLIN, POLLOUT with usual meaning. POLLHUP when host is not connected or when port or device got unplugged | |
Signals | From kernel 2.6.37, SIGIO will be sent to guest apps that set O_ASYNC flag on the fd. SIGIO will be sent on host connection up, down and port unplug events. |
For an example of a C program that uses the virtio-serial Linux guest API, see auto-virtserial-guest.c
Host API
There's an in-qemu host API exposed by the virtio-serial code. The following is true for the in-qemu API for qemu version 0.13 and for the qemu version found in Red Hat Enterprise Linux 6.0, straight from hw/virtio-serial.h:
|
In addition to this, the VirtIOSerialPortInfo struct has a function pointer for a callback to be called when guest writes some data to the port:
|
For an example use of this API, see hw/virtio-console.c