[mythtv-users] Xen DomU Backend & Nova-T

Thu Dec 25 18:50:59 UTC 2008

Hi Gerald,
    Thank you very much for your reply, I've recorded my first stream!!! ;-)
    But, and there's always a but! I couldn't get the domU to boot with
swiotlb=256,force, but it would work with just swiotlb=256.....  Have
you some documentation on swiotlb as I can't find any anywhere, there's
nothing meaningful in the kernel documentation....  So I don't know what
I've actually changed, and whether the focus is important?  Also I
assume the "-" in dom0_mem is deliberate?
    Again thank you very much for your help, I can feel a wiki entry on
mythtv.org coming on once I've got this working! ;-)

Regards

Alex

P.S. Apologies if this is sent twice I left the Digest subject on the 
last reply, but I think it was blocked due to this......

> Message: 12
> Date: Tue, 23 Dec 2008 18:53:04 -0600 (CST)
> From: Gerald Brandt <gbr at majentis.com>
> Subject: Re: [mythtv-users] Xen DomU Backend & Nova-T
> To: Discussion about mythtv <mythtv-users at mythtv.org>
> Message-ID: <17315252.261230080077978.JavaMail.gbr at vostro>
> Content-Type: text/plain; charset="utf-8"
>
> Hi, 
>
> I have 2 DomU's running, both with PVR-150's. One is the Master Backend, and the other is the slave. When the HDPVR becomes stable, I'll have 3 DomU's. 
>
> This is what I had to do on my Dom0 boot grub: 
>
> pciback.permissive pciback.hide=(06:01.0)(06:02.0) dom0_mem=-256M 
>
> Then on my DomU boot, I did: 
> extra = '2 console=xvc0 swiotlb=256,force' 
> #extra = '2 console=xvc0 iommu=soft swiotlb=512,force' 
> #extra = '2 console=xvc0' 
>
> pci=['06:01.0'] 
>
>
> The important things are the dom0_mem is dom0's grub, and the swiotlb in the DomU's configs. 
>
> I hope that helps. 
>
> Gerald 
>
> ps: if anyone gets pci passthrough working with Xen HVM, I'd be happy to hear about it. 
>
>
>
> ----- "Alex Pearson" <alex at apics.co.uk> wrote: 
>   
>> Hi All, 
>> I've done some searching and come up with nothing, so I hope I'm not 
>> walking well trodden ground here! 
>>
>> I wish to run my mythbackend in a Xen DomU, using pci forwarding. 
>> I've two different types of card, but I've only had chance to try one of 
>> them (If I pulled both out of my Production system the other half would 
>> kill me! ;-)). 
>>
>> The card I'm using is a Hauppauge Nova-T PCI (a dvb-t card) 
>> lspci on Dom0: 
>> 01:08.0 Multimedia video controller: Conexant CX23880/1/2/3 PCI Video 
>> and Audio Decoder (rev 05) 
>> 01:08.2 Multimedia controller: Conexant CX23880/1/2/3 PCI Video and 
>> Audio Decoder [MPEG Port] (rev 05) 
>> 01:08.4 Multimedia controller: Conexant CX23880/1/2/3 PCI Video and 
>> Audio Decoder [IR Port] (rev 05) 
>>
>> I've got the card passed to my domU fine (using 'pciback.permissive 
>> pciback.hide=(0000:01:08.0)(0000:01:08.2)(0000:01:08.4)' as a kernel 
>> option on the Dom0). I can scan for channels without any issues, but as 
>> soon as the card tries to actually record anything I get a kernel oops 
>> (pasted at the bottom of email). Is this because the card has tried to 
>> use DMA to pass the video and can't? Should this even work? The other 
>> card I have is a Hauppauge Nova-T 500, which I believe other people have 
>> got working (I believe this may be because the card basically a usb hub 
>> and tuners, and so wouldn't move data in the same way, but just a guess 
>> as I've not tested it yet). 
>>
>> lspci on DomU: 
>> 00:00.0 Multimedia video controller: Conexant CX23880/1/2/3 PCI Video 
>> and Audio Decoder (rev 05) 
>> 00:00.2 Multimedia controller: Conexant CX23880/1/2/3 PCI Video and 
>> Audio Decoder [MPEG Port] (rev 05) 
>> 00:00.4 Multimedia controller: Conexant CX23880/1/2/3 PCI Video and 
>> Audio Decoder [IR Port] (rev 05) 
>>
>> After the garbled chat above, I guess basically I'm asking: 
>>
>> Have people got mythbackend running in DomU's successfully? 
>> Have you used either Hauppauge Nova-T PCI or Hauppauge Nova-T 500? 
>>
>>
>> Thanks in advance to everyone. 
>>
>> Alex 
>>
>> Oops output: 
>> [14285.301630] Fatal DMA error! Please use 'swiotlb=force' 
>> [14285.302780] ----------- [cut here ] --------- [please bite here ] 
>> --------- 
>> [14285.304031] Kernel BUG at 
>> arch/x86_64/kernel/../../i386/kernel/pci-dma-xen.c:132 
>> [14285.305327] invalid opcode: 0000 [1] SMP 
>> [14285.306611] CPU 0 
>> [14285.307821] Modules linked in: ipv6 cx88_dvb cx8802 cx8800 
>> cx88_vp3054_i2c cx88xx ir_common mt352 i2c_algo_bit 
>> d vb_pll or51132 tveeprom 
>> video_buf_dvb compat_ioctl32 video_buf btcx_risc nxt200x videodev 
>> isl6421 v4l1_compat zl103 53 
>> v4l2_common cx24123 lgdt330x cx22702 i2c_core evdev joydev 
>> [14285.311737] Pid: 1014, comm: cx88[0] dvb Not tainted 2.6.18.8 #1 
>> [14285.313109] RIP: e030:[<ffffffff80211367>] [<ffffffff80211367>] 
>> dma_map_sg+0x141/0x1ae 
>> [14285.314457] RSP: e02b:ffff88001bfb3e00 EFLAGS: 00010282 
>> [14285.315781] RAX: 000000000000003e RBX: ffff88000161ebe0 RCX: 
>> 0000000100000000 
>> [14285.317103] RDX: ffffffffff5fd000 RSI: 0000000000000001 RDI: 
>> ffffffff805322e0 
>> [14285.318440] RBP: ffff88001ee0b2c0 R08: ffff880001827508 R09: 
>> 000000000000003c 
>> [14285.319812] R10: 0000000000001e62 R11: 0000000000001e27 R12: 
>> 0000000000000000 
>> [14285.321166] R13: 0000000000000006 R14: ffff880001a54070 R15: 
>> 6db6db6db6db6db7 
>> [14285.322510] FS: 00002b07b8f1d350(0000) GS:ffffffff805b4000(0000) 
>> knlGS:0000000000000000 
>> [14285.323875] CS: e033 DS: 0000 ES: 0000 
>> [14285.325223] Process cx88[0] dvb (pid: 1014, threadinfo 
>> ffff88001bfb2000, task ffff880001a1f100) 
>> [14285.326645] Stack: 0000000000000002 ffff88001f1f0230 
>> ffff88001eefe8e0 ffff880001a54000 
>> [14285.328099] ffff88001eefe800 ffff88001eefe8e0 0000000000000002 
>> ffffffff8804a1c2 
>> [14285.329592] ffff88001f1f0200 ffff88001eefe8e8 0000000000005e00 
>> ffffffff880a2f30 
>> [14285.329657] Call Trace: 
>> [14285.332451] [<ffffffff8804a1c2>] :video_buf:videobuf_dma_map+0x116/0x15a 
>> [14285.334086] [<ffffffff880a2f30>] :cx8802:cx8802_buf_prepare+0x9e/0xe6 
>> [14285.335944] [<ffffffff88049385>] 
>> :video_buf:videobuf_read_start+0xd9/0x167 
>> [14285.337587] [<ffffffff880563d2>] 
>> :video_buf_dvb:videobuf_dvb_thread+0x0/0x162 
>> [14285.339394] [<ffffffff8805641a>] 
>> :video_buf_dvb:videobuf_dvb_thread+0x48/0x162 
>> [14285.340942] [<ffffffff880563d2>] 
>> :video_buf_dvb:videobuf_dvb_thread+0x0/0x162 
>> [14285.342413] [<ffffffff8023dfa6>] keventd_create_kthread+0x0/0x62 
>> [14285.343885] [<ffffffff8023e0dc>] kthread+0xd4/0x108 
>> [14285.345364] [<ffffffff8020aac8>] child_rip+0xa/0x12 
>> [14285.346834] [<ffffffff8023dfa6>] keventd_create_kthread+0x0/0x62 
>> [14285.348328] [<ffffffff803f7885>] dmx_ts_feed_set+0x0/0x121 
>> [14285.349864] [<ffffffff8023e008>] kthread+0x0/0x108 
>> [14285.351362] [<ffffffff8020aabe>] child_rip+0x0/0x12 
>> [14285.352840] 
>> [14285.354268] 
>> [14285.354269] Code: 0f 0b 68 2b ac 4d 80 c2 84 00 48 8b 7d 00 48 2b 3d 
>> ec e7 40 
>> [14285.357142] RIP [<ffffffff80211367>] dma_map_sg+0x141/0x1ae 
>> [14285.358551] RSP <ffff88001bfb3e00> 
>> [14285.359917] 
>> focus:~# 
>>
>> xm dmesg: 
>> (XEN) Xen version 3.3-unstable (Debian 3.3-unstable+hg17961-1) 
>> (waldi at debian.org) (gcc version 4.3.1 (Debian 4.3.1-4) ) Fri Jul 4 
>> 18:44:42 UTC 2008 
>>
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