FAQ
CentOS-6.2

We have a dedicated CentOS-5.7 host used for fax reception
and transmission that we wish to move to a CentOS-6.2
virtual guest instance. The CentOS-6.2 virtual host has a
4-port serial card installed.

lspci -v tshows this this:

03:00.0 Serial controller: Oxford Semiconductor Ltd
OX16PCI954 (Quad 16950 UART) function 0 (Uart) (prog-if 06
[16950])
Subsystem: Oxford Semiconductor Ltd Device 0000
Flags: medium devsel, IRQ 17
I/O ports at d040 [size2]
Memory at d0702000 (32-bit, non-prefetchable)
[size=4K]
I/O ports at d020 [size2]
Memory at d0701000 (32-bit, non-prefetchable)
[size=4K]
Capabilities: [40] Power Management version 2
Kernel driver in use: serial


setserial -g /dev/ttyS* shows this:

/dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4
/dev/ttyS1, UART: 16950/954, Port: 0xd040, IRQ: 17
/dev/ttyS2, UART: 16950/954, Port: 0xd048, IRQ: 17
/dev/ttyS3, UART: 16950/954, Port: 0xd050, IRQ: 17


But, in virt-manage, when I try to add a serial device to
the guest as the physical character device /dev/ttyS1 I
get this error and the device is not added.

XML error: unknown device type

Traceback (most recent call last):
File
"/usr/share/virt-manager/virtManager/addhardware.py",
line 1026, in add_device
self.vm.attach_device(self._dev)
File "/usr/share/virt-manager/virtManager/domain.py",
line 698, in attach_device
self._backend.attachDevice(devxml)
File "/usr/lib64/python2.6/site-packages/libvirt.py",
line 400, in attachDevice
if ret == -1: raise libvirtError
('virDomainAttachDevice() failed', dom=self)
libvirtError: XML error: unknown device type

We wish to have at least two, preferably three, andf
ideally all four, serial ports enabled on the virtual
guest. Does anyone know how this is accomplished?

--
*** E-Mail is NOT a SECURE channel ***
James B. Byrne mailto:ByrneJB at Harte-Lyne.ca
Harte & Lyne Limited http://www.harte-lyne.ca
9 Brockley Drive vox: +1 905 561 1241
Hamilton, Ontario fax: +1 905 561 0757
Canada L8E 3C3

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  • Nenad Opsenica at Jan 31, 2012 at 4:15 pm
    Hi James,

    You should try to make a PCI pass-through for your multiport serial card
    in virt-manager.
    Although I haven't tried this kind of configuration, I think that this
    should be the right way to make such setup.
    You'll need driver for this PCI card within your guest OS.
    On 01/31/2012 08:01 PM, James B. Byrne wrote:
    CentOS-6.2

    We have a dedicated CentOS-5.7 host used for fax reception
    and transmission that we wish to move to a CentOS-6.2
    virtual guest instance. The CentOS-6.2 virtual host has a
    4-port serial card installed.

    lspci -v tshows this this:

    03:00.0 Serial controller: Oxford Semiconductor Ltd
    OX16PCI954 (Quad 16950 UART) function 0 (Uart) (prog-if 06
    [16950])
    Subsystem: Oxford Semiconductor Ltd Device 0000
    Flags: medium devsel, IRQ 17
    I/O ports at d040 [size2]
    Memory at d0702000 (32-bit, non-prefetchable)
    [size=4K]
    I/O ports at d020 [size2]
    Memory at d0701000 (32-bit, non-prefetchable)
    [size=4K]
    Capabilities: [40] Power Management version 2
    Kernel driver in use: serial


    setserial -g /dev/ttyS* shows this:

    /dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4
    /dev/ttyS1, UART: 16950/954, Port: 0xd040, IRQ: 17
    /dev/ttyS2, UART: 16950/954, Port: 0xd048, IRQ: 17
    /dev/ttyS3, UART: 16950/954, Port: 0xd050, IRQ: 17


    But, in virt-manage, when I try to add a serial device to
    the guest as the physical character device /dev/ttyS1 I
    get this error and the device is not added.

    XML error: unknown device type

    Traceback (most recent call last):
    File
    "/usr/share/virt-manager/virtManager/addhardware.py",
    line 1026, in add_device
    self.vm.attach_device(self._dev)
    File "/usr/share/virt-manager/virtManager/domain.py",
    line 698, in attach_device
    self._backend.attachDevice(devxml)
    File "/usr/lib64/python2.6/site-packages/libvirt.py",
    line 400, in attachDevice
    if ret == -1: raise libvirtError
    ('virDomainAttachDevice() failed', dom=self)
    libvirtError: XML error: unknown device type

    We wish to have at least two, preferably three, andf
    ideally all four, serial ports enabled on the virtual
    guest. Does anyone know how this is accomplished?
  • Mario Villela at Jan 31, 2012 at 4:23 pm
    buenas a todos

    una pregunta tengo que hacer una videoconfirecia publica donde se
    compartiran videos, mi problema es que el audio del video no se comparte
    como en striming y necesito eso, saben que cliente si con asterix o
    openmeeting se puede hacer eso???? o con cual herramiente se puede??
    gracias de antemano


    saludos a todos
  • Ed Heron at Feb 8, 2012 at 11:06 am

    On Tue, 2012-01-31 at 14:01 -0500, James B. Byrne wrote:
    CentOS-6.2

    We have a dedicated CentOS-5.7 host used for fax reception
    and transmission that we wish to move to a CentOS-6.2
    virtual guest instance. The CentOS-6.2 virtual host has a
    4-port serial card installed.
    Consider replacing your multi-serial port card with a VoIP analog
    gateway and use a pre-rolled Asterisk with virtual faxmodems, like
    Elastix. Just make sure your codec is high enough quality. We used to
    receive faxes using a dedicated Linux box with a Comtrol Rocketport and
    an USRobotics MP8. We Converted to SIP trunks and managed to get our
    faxes in the SIP trunks, as well.

    This will remove the PCI pass-through from the equation.
  • James B. Byrne at Feb 8, 2012 at 1:29 pm

    On Wed, February 8, 2012 11:06, Ed Heron wrote:
    On Tue, 2012-01-31 at 14:01 -0500, James B. Byrne wrote:
    CentOS-6.2

    We have a dedicated CentOS-5.7 host used for fax
    reception
    and transmission that we wish to move to a CentOS-6.2
    virtual guest instance. The CentOS-6.2 virtual host has
    a
    4-port serial card installed.
    Consider replacing your multi-serial port card with a
    VoIP analog
    gateway and use a pre-rolled Asterisk with virtual
    faxmodems, like
    Elastix. Just make sure your codec is high enough
    quality. We used to
    receive faxes using a dedicated Linux box with a Comtrol
    Rocketport and
    an USRobotics MP8. We Converted to SIP trunks and managed
    to get our
    faxes in the SIP trunks, as well.

    This will remove the PCI pass-through from the equation.
    After a brief read this seems to me the approach we should
    take. Recently I have discovered more about irqs, timing
    delays, and the difficulties/impossiblities of switching
    hardware from vm instances than I ever wanted to know.

    Given that we have three dedicated fax lines and 6 voice
    is there any hardware that would you suggest for a 4 core
    x86_64 Intel based host system?

    We have looked at going completely to v/f-oip but I do not
    have the time to deal with those intricacies and get this
    move completed at the same time. So, for the nonce it
    appears that we would have to employ an FXO gateway to
    connect our existing POTS lines to the host.


    --
    *** E-Mail is NOT a SECURE channel ***
    James B. Byrne mailto:ByrneJB at Harte-Lyne.ca
    Harte & Lyne Limited http://www.harte-lyne.ca
    9 Brockley Drive vox: +1 905 561 1241
    Hamilton, Ontario fax: +1 905 561 0757
    Canada L8E 3C3
  • Ed Heron at Feb 8, 2012 at 2:31 pm

    On Wed, 2012-02-08 at 13:29 -0500, James B. Byrne wrote:
    On Wed, February 8, 2012 11:06, Ed Heron wrote:
    On Tue, 2012-01-31 at 14:01 -0500, James B. Byrne wrote:
    CentOS-6.2

    We have a dedicated CentOS-5.7 host used for fax
    reception
    and transmission that we wish to move to a CentOS-6.2
    virtual guest instance. The CentOS-6.2 virtual host has
    a
    4-port serial card installed.
    Consider replacing your multi-serial port card with a
    VoIP analog
    gateway and use a pre-rolled Asterisk with virtual
    faxmodems, like
    Elastix. Just make sure your codec is high enough
    quality. We used to
    receive faxes using a dedicated Linux box with a Comtrol
    Rocketport and
    an USRobotics MP8. We Converted to SIP trunks and managed
    to get our
    faxes in the SIP trunks, as well.

    This will remove the PCI pass-through from the equation.
    After a brief read this seems to me the approach we should
    take. Recently I have discovered more about irqs, timing
    delays, and the difficulties/impossiblities of switching
    hardware from vm instances than I ever wanted to know.

    Given that we have three dedicated fax lines and 6 voice
    is there any hardware that would you suggest for a 4 core
    x86_64 Intel based host system?

    We have looked at going completely to v/f-oip but I do not
    have the time to deal with those intricacies and get this
    move completed at the same time. So, for the nonce it
    appears that we would have to employ an FXO gateway to
    connect our existing POTS lines to the host.
    It might be OK to virtualize a fax server, but I wouldn't switch to a
    new voice tech and virtualize it at the same time.

    If you are interested in moving to a VoIP phone system, you should get
    familiar with how it works before adding the virtual component.

    Currently, I'm running a couple of locations using Elastix with
    dedicated hardware. One location supports 6 users with an Intel D845G
    integrated desktop board with a 1.7 Celeron and 1G RAM, so the hardware
    requirements are pretty low, but virtualized machines are not
    necessarily real-time.

    I would consider virtualizing it if I dedicated a server CPU and
    network card, but you'd need to find an external analog VoIP gateway
    that you are comfortable with. I'm currently using internal Digium
    cards for T1 and analog connectivity, but obviously I'd want to move to
    an external gateway or move to pure SIP before virtualizing to avoid
    having a PCI passthrough issue of my own.

    Just make sure that your phone line vendor is not using VoIP
    internally and handing you an emulated analog interface. I had quite a
    mess when I tried connecting an analog/VoIP external gateway to some
    emulated analog lines. The 2 analog emulations didn't quite mesh and I
    had miscellaneous dropped calls. The issue hurt my department's
    credibility and led to a longer implementation schedule for our VoIP
    project.

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postedJan 31, '12 at 2:01p
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