This is a proprietary FPGA device. Each control blade in
our router chassis has one of these FPGAs and its primary function is to control
certain dedicated hardware components on the blade that are responsible for
establishing connectivity with the high-speed inter-blade fabric on the router.
I am sorry, but I cannot divulge additional details regarding the
FPGA.
Here is a more detailed description of my actual usage
scenario.
1) The FPGA image must be downloaded onto the device before
it can be enabled for use.
2) The VM in question is responsible for performing step
(1), which means that the FPGA is not visible to Xen/Dom-0 when
the VM is powered
on.
3) After the VM performs step (1), the FPGA is seen in
Dom-0. I use Xen pci-hotplug to assign the device to the VM.
This operation completes successfully
(as reported by the appropriate xl command).
4) However, the guest OS inside the VM cannot see the FPGA
device after step (3).
5) If I shutdown the VM and re-start it, the guest OS
inside the VM sees the FPGA device (and everything then proceeds
normally).
The troublesome part here is that I need to shutdown and
restart the VM. I would like to avoid this and rely on Xen pci-hotplug to make
the device visible to the guest OS inside the VM.
Thanks.
-Anil
From:
xen-users-bounces@xxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxx] On
Behalf Of cyberhawk001@xxxxxxxxx
Sent: Thursday, May 31, 2012
10:49 AM
To: xen-users@xxxxxxxxxxxxx
Subject: Re:
[Xen-users] Hotplugging FPGA to running VM
Just out of curiosity, what kind of FPGA device is this? Is it
an FPGA development board or something already assembled and functioning that
contains an FPGA device(s)?
Well, just being curious...
:)
Yes, the guest OS has PCI hotplug support. I am able
to hotplug a variety of PCI devices to the VM. The only one that doesn't work
is the FPGA device. Even for this one, the only time it doesn't work, is if
the VM was powered-on prior to the FPGA device being brought on-line on the
host. If the FPGA was present before the VM was powered-on everything works as
expected.
It somehow seems like new devices that are introduced
in the host, after a VM has been started on it, cannot be hotplugged into the
VM.
Thanks.
-Anil
Are you
sure the guest OS has PCI hotplug support?
On Wed, May 30, 2012 at 10:14 PM, Anil Rao
<anil.rao@xxxxxxxxxxxx> wrote:
Hi,
I am trying to assign a FPGA (which is a PCI device) to a running VM.
The interesting thing here is that the FPGA is not present when the VM was
powered-on. I.e. sometime after the VM was started, the FPGA was brought
on-line on the host by downloading its image to the device.
So far my attempts at using Xen PCI-passthrough have not been
successful. Although Xen reports that the pass-through operation was
successful, which I have verified using the appropriate xl command, I am
unable to see the FPGA from within the guest OS.
I have tried both manual rescanning of the PCI bus inside the guest as
well as making use of the pciehp driver. The only way I can (reliably) see
the FPGA from within the guest, is to shutdown and restart the VM and then
redo the hotplug operation. I want to avoid a VM reboot and was wondering if
this is at all possible and if so what do I need to do to realize it.
[The virtualization host is based on the default Xen setup that comes
with SLES 11 SP2]
Thanks for any help on this matter.
-Anil
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