Re: Mentor of the Project "PCI frontend XEN PV driver"?

Bei Guan gbtju85 at
Thu Apr 18 13:14:39 UTC 2013

2013/4/16 Justin T. Gibbs <gibbs at>

> On Apr 12, 2013, at 3:02 AM, Bei Guan <gbtju85 at> wrote:
> > Thank you for your reply.
> >
> > I think it's also a good project for me to write a SCSI or USB PV
> frontend for FreeBSD. I'm interest in Xen and have done some development
> about Xen PV and HVM, but I didn't do any development on FreeBSD. As to
> this project, where should I start? Is there any other similar FreeBSD
> project I can refer to?
> Front-end drivers for network, block, and control already exist and should
> serve as a good starting point for the creation of another PV driver.
> I've also updated the ideas page to include more information about our
> existing XEN implementation and what will be required for these projects.
> > In order to write a SCSI or USB PV driver, do we need the Xen PV drivers
> in FreeBSD, such as event channel, hypercalls, xenbus, and so on?
> Yes, FreeBSD already has support for all XenBus APIs needed to write these
> drivers.  See "sys/xen" and "sys/dev/xen" in the FreeBSD kernel source tree.
> > You said the "drivers can be developed using an HVM guest", can you give
> me more information about it?
> Typically, you install FreeBSD using standard install media as a full HVM
> guest on a system running Xen.  Then compile a custom kernel using the
> XENHVM config file in order to activate the existing PV drivers.
Hi Justin,

Does this project need to provide USB/SCSI PV drivers to both 32-bit and
64-bit FreeBSD?
I've compiled the FreeBSD 8.3 (i386) as Xen DomU with the XENHVM config.
But, It cannot boot successfully. The screenshot is attached.
According to the page , 32-bit FreeBSD
should work when compiled with XENHVM config.

I will try the 64-bit FreeBSD. However, if the FreeBSD boot successfully
(compiled with XENHVM config), how can we know it really uses the PV
drivers instead of the native drivers?

Bei Guan

> --
> Justin

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