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

[Alex Pearson]

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