Greetings list! On the xen wiki, under "cool configurations", a user remarked they had gotten a mythtv backend running under a xen virtual machine, complete with a pvr500 dual tuner capture card. I''m building a new server for home and would like to virtualize myth if possible, since it likes to crash often, and usually takes the rest of linux with it. (crashes are related to ivtv drivers for the card). No details were given as to how the user accomplished his goal. Is that user on this list? Does he have a website? Can anyone share more details? Thanks for your time, Gordon _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> I''m building a new server for > home and would like to virtualize myth if possible, since it likes to > crash often, and usually takes the rest of linux with it. (crashes are > related to ivtv drivers for the card).Can''t help you much, except that depending on the crash you are seeing, xen may not be the answer to your problems... What is the nature of your crashes? James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
James (and list), The crashes seem to be DMA related ... but I''m not sure what the "trigger" is - it''s not high disk load or high cpu load... perhaps low memory is the cause? The card (pvr500) is actually two codecs sharing one pci interface ... both will be capturing video, and then the capture output stops, usually on the second codec only (ivtv1). All that is reported in the logs is DMA timeout ivtv1. Sometimes the system will run like that for days, without me noticing any degradation in other services, other times, it will crash quick, tying up hard drives like there is some sort of bus contention, leaving me no choice but to hit the reset button On a soft crash (one that doesn''t kill the box) I''ve tried to "recover" without rebooting by unloading the kernel module (rmmod ivtv) and loading it again. This results in a segfault logged by the kernel, and things go down hill from there. The segfault cites being unable to allocate DMA memory to the driver, again, usually for only the second codec (ivtv1). This problem (or ones similar to it) is documented various places, but no one has found a concrete cause or a solution. Some suggest the card is defective, but I''m thinking it is a software problem. Before Centos 5 came along with the 2.6.18 kernel, I ran the card under Centos 4 with a (more or less) vanilla 2.6.20 kernel and had no problems. My guess is the ivtv drivers do not like the taste of a redhat kernel. Problem there was I felt a bit "naked" running a vanilla kernel, and having to update it manually now and again also grew tiresome. I was hoping to virtualize the myth backend server so I could try different flavors of linux, or run a vanilla kernel without having to worry about keeping it current, as long as it works. Gordon On Tue, Mar 25, 2008 at 7:28 PM, James Harper <james.harper@bendigoit.com.au> wrote:> > I''m building a new server for > > home and would like to virtualize myth if possible, since it likes to > > crash often, and usually takes the rest of linux with it. (crashes are > > related to ivtv drivers for the card). > > Can''t help you much, except that depending on the crash you are seeing, > xen may not be the answer to your problems... > > What is the nature of your crashes? > > James >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > The crashes seem to be DMA related ... but I''m not sure what the > "trigger" is - it''s not high disk load or high cpu load... perhaps low > memory is the cause? > > The card (pvr500) is actually two codecs sharing one pci interface ... > both will be capturing video, and then the capture output stops, > usually on the second codec only (ivtv1). All that is reported in the > logs is DMA timeout ivtv1. > > Sometimes the system will run like that for days, without me noticing > any degradation in other services, other times, it will crash quick, > tying up hard drives like there is some sort of bus contention, > leaving me no choice but to hit the reset button On a soft crash > (one that doesn''t kill the box) I''ve tried to "recover" without > rebooting by unloading the kernel module (rmmod ivtv) and loading it > again. This results in a segfault logged by the kernel, and things go > down hill from there. The segfault cites being unable to allocate DMA > memory to the driver, again, usually for only the second codec > (ivtv1).Those sort of symptoms make me thing that even under Xen, the card will still crash your PCI bus, crashing not only that DomU but also Dom0 and therefore the whole box. If you can test it easily then go for it, but I''d suggest putting it on a box on it''s own with a watchdog timer to detect failures. Or just get another DVB card, although I understand that the pvr500 is a fairly nice piece of equipment. James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 25/03/2008, Gordon McLellan <gordonthree@gmail.com> wrote:> The card (pvr500) is actually two codecs sharing one pci interface ... > both will be capturing video, and then the capture output stops, > usually on the second codec only (ivtv1). All that is reported in the > logs is DMA timeout ivtv1.If you''re not running ivtv 0.10.6 grab yourself the most recent ivtv driver (ivtvdriver.org). If you are already using 0.10.6 you should consider a newer kernel and the most recent 1.0.x ivtv driver. Yes, building your own kernels can be a drag, but not nearly as much an unstable box. You should also look into what IRQs your PVR-500 is using (lspci -v) and whether it is sharing any with something that requires a lot of interrupts (like a NIC). I expect you will find that your second encoder is sharing an IRQ with something else. Try to get it so that both encoders are not sharing IRQs. Unfortunately underlying hardware issues like what you are experiencing don''t go away when you switch to xen, though often you can get away with merely restarting the domU that is having problems, sometimes it''ll take down the whole box and/or whatever other piece of hardware it is conflicting with. You''ll be adding a layer of complexity to your current set-up. - Ben _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users