Virtio-serial API: Difference between revisions
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|Port discovery | |Port discovery | ||
|symlinks from <code> /dev/virtio-port/<portname> </code> to <code> /dev/vportNpn </code> as mentioned in http://www.linux-kvm.org/page/VMchannel_Requirements#Invocation | |symlinks from <code> /dev/virtio-port/<portname> </code> to <code> /dev/vportNpn </code> as mentioned in http://www.linux-kvm.org/page/VMchannel_Requirements#Invocation and http://fedoraproject.org/wiki/Features/VirtioSerial#How_To_Test | ||
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* <code>POLLHUP</code> when host is not connected or when port or device got unplugged | * <code>POLLHUP</code> when host is not connected or when port or device got unplugged | ||
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|<code> | |Asynchronous notifications | ||
|<code>signal(7)</code> | |||
* From kernel 2.6.37, <code>SIGIO</code> will be sent to guest apps that set <code>O_ASYNC</code> flag on the fd using <code>fcntl(2)</code>. | |||
* <code>SIGIO</code> will be sent on host connection up, down and port unplug events. | |||
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Revision as of 07:20, 2 September 2010
Guest API
Function | Linux guest | Windows guest |
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Port discovery | symlinks from /dev/virtio-port/<portname> to /dev/vportNpn as mentioned in http://www.linux-kvm.org/page/VMchannel_Requirements#Invocation and http://fedoraproject.org/wiki/Features/VirtioSerial#How_To_Test
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Opening port | open(2) .
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Reading | read(2).
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Writing | write(2) .
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Poll | poll() .
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Asynchronous notifications | signal(7)
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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:
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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:
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For an example use of this API, see hw/virtio-console.c