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Re: [Xen-users] VT-d "partial" success - passing DVB-S tuner to Windows DomU (based off previous thread of similar name!)



Hi Johannes,

your chipset needs to support IOMMU. As far as I've seen this in different
papers and on xen-devel, an additional amd_enable_iommu=1 entry in the grub
line should enable this for xen.

I don't know where to find a list of chipsets supporting this feature.
ht2000/ht1000 does not, ht1100 should (at least Wei Wang posted a patch for
that chipset in February, don't know if this made it to the mainline).

I suggest you posting this question with a description of your hardware
on xen-devel.

good luck!

Stephan



Johannes t. schrieb:
Hello Daniel, hello Stefan, hello xen-users,

just read this thread with high interest, read through what the Wiki has on VT-D. I wonder if or when the AMD IOMMU will be usable to do the same. I have an AMD 2400BE here (Dualcore, 2,3GHz, SVM, x64) and I happen to have some funny PCI card that will only work with Windows.

I did not find anything production ready on AMD IOMMU, I do see the AMD IOMMU switchoff line when Xen is booting.

Could someone please give a short status notice on what happens with HVM PCI passthrough and AMD?

Thanks in advance :)

Regards,
Johannes

Am 28. Juli 2008 09:17 schrieb Stephan Seitz <s.seitz@xxxxxxxxxxxx <mailto:s.seitz@xxxxxxxxxxxx>>:

    Hi Daniel,

    it's speculative, but have you additionally tried to use only one cpu
    and pin that one to core?

    domU:

    # no SMP
    vcpus = '1'
    # second core
    cpu = '1'

    Daniel Kao schrieb:

        Hi Stephan,

        Thanks for the response.

        I actually tried leaving default settings and irqbalance was
        installed by default in my CentOS 5.2 install.  Maybe I should
        try turning irqbalance off?  It definitely seems to be
        irq-related.  :(

        03:02pm root@vps-cluster-01:/root% service irqbalance status
        irqbalance (pid 3585) is running...
        03:04pm root@vps-cluster-01:/root%

        Cheers,
        Daniel

        Stephan Seitz wrote:

            Hi,

            I noticed similar behaviour of missing interrupts in domU's
            (well, PV/pci-
            passthrough) if the dom0 is under load (sometimes only
            slightly above
            idle has been enough).

            Leaving dom0 all cpu's (just the default settings) and
            installing irqbalance
            in dom0 solved this issue.

            I don't know if it's of much use to you, but it's worth to
            try ;)


            cheers,

            Stephan


            Daniel Kao schrieb:

                Hi All,

                So I've got a DVB-S PCI Express card ($30 USD Twinhan
                AD-SE200 off eBay) that's being passed via VT-d/pciback
                in Xen 3.2.1 under CentOS 5.2 to a Windows XP SP3 which
                works! ... except for one small issue...

                Motherboard is an Intel DQ35JO that much people has had
                success with and an Intel E8400 CPU.

                The issue is that when dealing with FTA MPEG-2 transport
                streams (DVB-S based @ Galaxy 25 @ 97.0W), all is well
                until I start putting a slight I/O (whether disk or
                otherwise) load under dom0.  The issue is very similar
                and indicative of TV tuner cards and other PCI devices
                which have poorly matched PCI latency timers.  Basically
                when dom0 isn't under load, the DVB-S card and Windows
                XP SP3 works great.  Once there's a slight load (I/O
                load; not CPU) in dom0, I get continuity errors in the
                MPEG-2 packet transport stream.  Normally, this is an
                issue with signal strength of the receiving satellite,
                but this is not the issue.  These continuity errors are
                easily reproducible.  All I have to do is log into my
                CentOS dom0's gnome desktop via vnc (thru vncserver),
                launch the "Virtual Machine Manager", and instantly the
                MPEG-2 packet stream will start seeing continuity and
                stream errors.  The instant I close the "Virtual Machine
                Manager" and log out of X, everything returns to normal.

                There's also a Dell PERC 5/i card (flashed to an LSI
                MegaRAID 8408E firmware) that's running 8-750GB drives
                in RAID-5 which is visible in dom0 as a file-server
                using samba.  And that's about it.

                I'm not sure where to start looking in resolving this
                issue but issues of this type when searching other
                forums and answers seems to be PCI latency related and
                resetting them on certain PCI bus devices to fix
                continuity errors (even in a non-VM environment and
                straight up Windows-based OS).  Doing an lspci -vvv on
                dom0 under a Xen kernel, I noticed every single device
                on the PCI and PCIe has a latency set to 0 which I find
                very odd (or is that normal for native PCIe based
                chipsets?).  Also, I'm not even sure PCI latency affects
                PCIe devices as they do PCI devices (especially since
                the Q35 chipset is natively PCI-Express and all legacy
                PCI devices are being a PCIe-to-PCI bridge).  Or... am I
                just barking up the wrong tree? ;)

                I can post a lspci -vvv if that would help.  Since the
                domU is HVM and it's Windows XP, I've tried using the
                "PCI Latency Tool 3.1.2" but the PCIe DVB-S card would
                not show in the list of PCI devices.  Other testing I've
                done, I started off using "ACPI Multiprocessor" as the
                HAL, then dropped to the more stable "Standard PC" HAL
                (so going back to the ACPI HAL means a re-install of the
                OS), and then disabling ACPI and APIC and turning off
                PAE... etc.  It has no affect.

                Anyone have any ideas?  Thanks in advance!

-- Daniel Kao
                Ãbermind, Inc.
                Seattle, WA, U.S.A.


                
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-- Stephan Seitz
    Senior System Administrator

    *netz-haut* e.K.
    multimediale kommunikation

    zweierweg 22
    97074 wÃrzburg

    fon: +49 931 2876247
    fax: +49 931 2876248

    web: www.netz-haut.de <http://www.netz-haut.de>
    <http://www.netz-haut.de/>

    registriergericht: amtsgericht wÃrzburg, hra 5054

    _______________________________________________
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_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users


--
Stephan Seitz
Senior System Administrator

*netz-haut* e.K.
multimediale kommunikation

zweierweg 22
97074 wÃrzburg

fon: +49 931 2876247
fax: +49 931 2876248

web: www.netz-haut.de <http://www.netz-haut.de/>

registriergericht: amtsgericht wÃrzburg, hra 5054

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