libvirt users - Sep 2013 - virtio channel socket bind error

Hi All,
  My intent is to make virtio unix channel work. I could configure the XML and
launch VM and could see the port in /dev/virtio-ports

   <channel type='unix'>
      <source mode='bind' path='/tmp/appl_port'/>
      <target type='virtio' name='appl_port'/>
      <address type='virtio-serial' controller='0'
bus='0' port='1'/>
    </channel>

When I see on the host, the unix socket is already binded and is in listening
state.

echo "test this" > /tmp/appl_port
bash: /tmp/appl_port: No such device or address

netstat -nax | grep appl_port
unix  2      [ ACC ]     STREAM     LISTENING     15302258 /tmp/appl_port

1) Can some one please have a look and help me fix this.
2) if I don't set source mode to 'bind', it gets set to
'connect' in xml and VM fails to boot up. I would like to understand the
different types of source mode.
Dmesg shows below denied message for connect mode.
84616.025345] type=1400 audit(1380129082.835:210): apparmor="DENIED"
operation="capable" parent=1 profile="/usr/sbin/libvirtd"
pid=9804 comm="libvirtd" pid=9804 comm="libvirtd"
capability=29  capname="audit_write"

Thanks,
-Ravi.

I am assuming source mode is for the host. Bind means server and connect would
mean client.

The other part is still pending.
On host, when I run cat  it gives no such device or address

Or a  python program to bind the socket (in my case /tmp/appl_port) it gives
'unable to connect to virtio-serial port. Error: %s', error(111,
'Connection refused'))

Am I missing something?

Thanks,
-Ravi.

From: "<Chunduru Venkata>", "Chunduru Venkata, Ravi"
<schunduruvenkata@paypal.com<mailto:schunduruvenkata@paypal.com>>
Date: Wednesday, September 25, 2013 10:17 AM
To: "libvirt-users@redhat.com<mailto:libvirt-users@redhat.com>"
<libvirt-users@redhat.com<mailto:libvirt-users@redhat.com>>
Subject: [libvirt-users] virtio channel socket bind error

Hi All,
  My intent is to make virtio unix channel work. I could configure the XML and
launch VM and could see the port in /dev/virtio-ports

   <channel type='unix'>
      <source mode='bind' path='/tmp/appl_port'/>
      <target type='virtio' name='appl_port'/>
      <address type='virtio-serial' controller='0'
bus='0' port='1'/>
    </channel>

When I see on the host, the unix socket is already binded and is in listening
state.

echo "test this" > /tmp/appl_port
bash: /tmp/appl_port: No such device or address

netstat -nax | grep appl_port
unix  2      [ ACC ]     STREAM     LISTENING     15302258 /tmp/appl_port

1) Can some one please have a look and help me fix this.
2) if I don't set source mode to 'bind', it gets set to
'connect' in xml and VM fails to boot up. I would like to understand the
different types of source mode.
Dmesg shows below denied message for connect mode.
84616.025345] type=1400 audit(1380129082.835:210): apparmor="DENIED"
operation="capable" parent=1 profile="/usr/sbin/libvirtd"
pid=9804 comm="libvirtd" pid=9804 comm="libvirtd"
capability=29  capname="audit_write"

Thanks,
-Ravi.

I got this working.
I have to treat the port as char device on guest and unix socket on the host and
that too as client.

Thanks,
-Ravi.

From: "<Chunduru Venkata>", "Chunduru Venkata, Ravi"
<schunduruvenkata@paypal.com<mailto:schunduruvenkata@paypal.com>>
Date: Wednesday, September 25, 2013 10:48 AM
To: "libvirt-users@redhat.com<mailto:libvirt-users@redhat.com>"
<libvirt-users@redhat.com<mailto:libvirt-users@redhat.com>>
Subject: Re: [libvirt-users] virtio channel socket bind error

I am assuming source mode is for the host. Bind means server and connect would
mean client.

The other part is still pending.
On host, when I run cat  it gives no such device or address

Or a  python program to bind the socket (in my case /tmp/appl_port) it gives
'unable to connect to virtio-serial port. Error: %s', error(111,
'Connection refused'))

Am I missing something?

Thanks,
-Ravi.

From: "<Chunduru Venkata>", "Chunduru Venkata, Ravi"
<schunduruvenkata@paypal.com<mailto:schunduruvenkata@paypal.com>>
Date: Wednesday, September 25, 2013 10:17 AM
To: "libvirt-users@redhat.com<mailto:libvirt-users@redhat.com>"
<libvirt-users@redhat.com<mailto:libvirt-users@redhat.com>>
Subject: [libvirt-users] virtio channel socket bind error

Hi All,
  My intent is to make virtio unix channel work. I could configure the XML and
launch VM and could see the port in /dev/virtio-ports

   <channel type='unix'>
      <source mode='bind' path='/tmp/appl_port'/>
      <target type='virtio' name='appl_port'/>
      <address type='virtio-serial' controller='0'
bus='0' port='1'/>
    </channel>

When I see on the host, the unix socket is already binded and is in listening
state.

echo "test this" > /tmp/appl_port
bash: /tmp/appl_port: No such device or address

netstat -nax | grep appl_port
unix  2      [ ACC ]     STREAM     LISTENING     15302258 /tmp/appl_port

1) Can some one please have a look and help me fix this.
2) if I don't set source mode to 'bind', it gets set to
'connect' in xml and VM fails to boot up. I would like to understand the
different types of source mode.
Dmesg shows below denied message for connect mode.
84616.025345] type=1400 audit(1380129082.835:210): apparmor="DENIED"
operation="capable" parent=1 profile="/usr/sbin/libvirtd"
pid=9804 comm="libvirtd" pid=9804 comm="libvirtd"
capability=29  capname="audit_write"

Thanks,
-Ravi.

On 25.09.2013 19:17, Chunduru Venkata, Ravi wrote:
> Hi All,
>   My intent is to make virtio unix channel work. I could configure the
> XML and launch VM and could see the port in /dev/virtio-ports
> 
>    <channel type='unix'>
>       <source mode='bind' path='/tmp/appl_port'/>
>       <target type='virtio' name='appl_port'/>
>       <address type='virtio-serial' controller='0'
bus='0' port='1'/>
>     </channel>
> 
> When I see on the host, the unix socket is already binded and is in
> listening state.
> 
> echo "test this" > /tmp/appl_port
> bash: /tmp/appl_port: No such device or address
> 
> netstat -nax | grep appl_port
> unix  2      [ ACC ]     STREAM     LISTENING     15302258 /tmp/appl_port
> 
> 1) Can some one please have a look and help me fix this.
There's nothing to fix. This works as expected.
> 2) if I don't set source mode to 'bind', it gets set to
'connect' in xml
> and VM fails to boot up. I would like to understand the different types
> of source mode.
There are two modes: 'bind' and 'connect'. They represent the
UNIX
sockets modes. Either an application connects to something ('connect')
using the socket path as unique identifier telling where to connect, or
an application listens for incoming connections, again using the socket
path as unique identifier. Hence, if you want to use 'connect' mode, you
already need to have an application listening on the socket path when
starting up a domain. Otherwise the domain will get an error while
connecting to the socket. Or, you have to tell you application to
connect to the socket created by 'bind' mode once the domain is started.

Michal

On 25.09.2013 19:17, Chunduru Venkata, Ravi wrote:
> Hi All,
>  My intent is to make virtio unix channel work. I could configure the
> XML and launch VM and could see the port in /dev/virtio-ports
>
>    <channel type='unix'>
>      <source mode='bind' path='/tmp/appl_port'/>
>      <target type='virtio' name='appl_port'/>
>      <address type='virtio-serial' controller='0'
bus='0' port='1'/>
>    </channel>
>
> When I see on the host, the unix socket is already binded and is in
> listening state.
>
> echo "test this" > /tmp/appl_port
> bash: /tmp/appl_port: No such device or address
Try this:

   echo "test this" | socat - UNIX-CONNECT:/tmp/appl_port

You can't write to socket files the way you write to normal files.

Cheers,
Cristian Ciupitu