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