Re: [Xen-devel] Bug for Xen-3.3.0-rc2: libpci read error. No emulation.

[Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx>]

I found that current FLR logic seems to cause hot-plug issue.

On current implementation, hot-plug is done as follows.

    1. xend sends 'pci-ins' command to ioemu via xenstore.

    2. ioemu creates pass-through device and raises SCI to Guest
       OS. Guest OS loads device driver, and device driver initializes
       the hot-plugged device.

    3. xend does FLR(include bus reset and acpi reset).

Actually 2 and 3 are parallel. But it is possible xend does FLR after
device driver initialize the device. This cause hot-plug issue.

To fix the issue, xend should do FLR before sending 'pci-ins' command.


I will take more than a week holiday starting tomorrow. I will not be
able to reply the mail.

Thanks.

On Mon, 04 Aug 2008 16:18:56 +0900
Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx> wrote:

> libpci error handling has been fixed in the latest ioemu-remote and
> ioemu in xen-3.3.0-rc3-pre. If you test them, libpci read error
> will disappear.
> 
> But I think hotplug issue is not caused by libpci read error.
> 
> I tested xen-3.3.0-rc3-pre (changeset:18212) with ioemu-remote
> (commit:0a8ce1e7a87126a544f23209ef3a87346601f18a).  "libpci read
> error" did not appear, but hotplugged NIC did not work.  I checked
> /proc/interrupts on guest os, and found that guest os received msi
> only once.
> 
> I try to find out the reason of the issue.
> 
> Thanks
> 
> --
> Yuji Shimada
> 
> > On 32e, we create one guest, then hotplug attach one NIC to guest, guest
> > can not get IP address via dhcp, guest qemu log shows "libpci read
> > error. No emulation ".
> > 
> > Here is the bug entry:
> > One 32e, hotplug attaching VT-d NIC to guest failed.
> > http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1316.
> > 
> > -- haicheng
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> 
> _______________________________________________
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--
Yuji Shimada

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