Re: [Xen-users] pci passthrough how to that works?

[Matthias Reif <mattreif@xxxxxxxxxxxxx>]

> On Jan 6, 2010, at 2:57 PM, Matthias Reif wrote:
> 
> 
> 
> xen-users-bounces@xxxxxxxxxxxxxxxxxxx wrote on 07/01/2010 09:32:23
AM:
> 
> > Hi,
> > 
> > I'm running Centos 5.3 for dom0 and domUs and using Xen 3.4.1
(AMD V  
> > enabled Sun box).
> > 
> > Using lspci, I see that my device I wished ignored by dom0 so
that I  
> > can use it for 1 of my domUs is;
> > 
> > 07:00.0
> > 
> > In grub.conf, I added this to my module line;
> > 
> > pciback.permissive pciback.hide (07:00.0)
> > 
> > Upon reboot, lspci on dom0 still shows that pci device.
> > 
> > I've also modded my modprob.conf;
> > 
> > options pciback hide=(07:00.0)
> > 
> > Any ideas how I can get pci passthrough to work?
> > 
> > - Brian
> > 
> 
> The pciback module needs to be loaded into initrd, so it can seize
> the device at boot time. 
> Your boot log should confirm this if it says something like "unknwon
> kernel option pciback.hide 
> ignoring." 
> 
> Try something like this: 
> 
> mkinitrd -f --preload=pciback /boot/initrd-$(uname -r).img $(uname
-r) 
> 
> Also, pciback has to be loaded before the driver for your device.
> This is not always the case. 
> I tried to seize a SCSI controller to pass a tape drive to a domU,
> but its driver had to be loaded 
> first to get access to the disks where the initrd etc is stored (I
> presume). When pciback was loaded 
> the driver had already taken control of the device. 
> If that's the case, late binding may be an option for you, where you
> unbind the driver from the 
> device after the system has booted and then bind it to pciback prior
> to starting your domU. 
> 
> Eg. 
> # echo -n 0000:07:00.0 > /sys/bus/pci/drivers/<your_driver_name>/unbind
> # echo -n 0000:07:00.0 > /sys/bus/pci/drivers/pciback/new_slot
> # echo -n 0000:07:00.0 > /sys/bus/pci/drivers/pciback/bind 
> 
> 
> Matthias 
> 
> 
> 
> 
Brian Krusic <brian@xxxxxxxxxx> wrote on 07/01/2010 12:26:27 PM:

> Hi Matthias,
> 
> Heres what I did;
> 
> mkinitrd -f –preload=pciback /boot/initrd-$(uname -r).img $(uname
-r)
> 
> Then added this line to modprob.conf
> 
> options pciback hide=(07:00.0)
> 
> After a reboot, I still see the device under lspci, is this normal?
> 
> I went ahead and added this to the file xend-pci-permissive.sxp;
> 
> (unconstrained_dev_ids
> #(’0123:4567:89AB:CDEF’)
> (’10de:042f’)
> ) 
> 
> I got the 10de:042f from doing this;
> 
> lspci -n
> 
> Which gave;
> 
> 07:00.00 0300: 10de:042f (rev a1)
> 
> The next step is to assign this PCI device to domU.  In normal
> syntax I would simply edit domU config file and add;
> 
> pci = [ "07:00.0"]
> 
> But my domU configs are now using config.sxp which is this new 
> bloody XML format.
> 
> How do I put pci = [ "07:00.0"] in this XML format?
> 
>  
> - Brian
> 


First make sure that the new initrd that you built
with pciback included is
also referred to in your /boot/grub/grub.conf

Secondly I would put the pciback module options also
into grub.conf. I am not
sure whether modprobe.conf is actually used at boot
time.

Eg.
title CentOS (2.6.18-128.4.1.el5xen) Hypervisor 3.4.1
CentOS dom0
        root (hd0,0)
        kernel /xen.gz-3.4.1
        module /vmlinuz-2.6.18-128.4.1.el5xen
ro root=/dev/md1 pciback.hide=(07:00.0)
        module /initrd-2.6.18-128.4.1.el5xen.img


Then check dmesg to confirm that pciback is loaded
and is trying to seize the device.

If dmesg indicates that it is ignoring the pciback.hide
kernel parameter then there
is still something wrong.

Matthias



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