Re: [Xen-devel] DL385 G2 - PCI-DMA: Random memory would be DMAed

[Zachary Richmond <admin.ihsdoor@xxxxxxxxx>]

Keir Fraser wrote:
> On 18/10/07 20:05, "Zachary Richmond" <zak@xxxxxxxxxxx> wrote:
>
> > Regarding the full error message, all I am getting is:
> >
> > kernel panic not syncing: PCI-DMA: Random memory would be DMAed
> >
> > since the machine is rebooting after that.  There maybe somewhere else to get
> > more detail, but beyond dmesg or messages I am not sure where else to look.
> You should also get a line immediately before that saying:
> "PCI-DMA: Out of SW-IOMMU space for xxx bytes at device xxx"
>
> This message makes it clear that your swiotlb is not big enough. The default
> size is 2MB if your machine has less than 2GB RAM. Otherwise the default is
> 64MB. You can increase the swiotlb size by, for example, adding
> 'swiotlb=128' as a boot parameter to your dom0 kernel (the example here
> would set the swiotlb size to be 128MB).
>
> Setting the parameter too small will make your system crash (as you have
> seen). Setting it bigger than necessary will waste memory. The optimum
> setting will depend on your system.
>
>  -- Keir
Thanks for the tip.  If Mark's suggestion doesn't work I'll have to give this a 
try as well, but I wasn't receiving that error message.  When I looked at the 
source code it seems like I should be getting that error message as well, but 
it is a printk call which I think is sent to dmesg which is overwritten at the 
next boot.  I guess I could boot off a cd or into a different file system to 
preserve dmesg if the problem persists.
        Zak

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