Re: [Xen-devel] Can I specify a physical memory region for a domU

[Eric Camachat <eric.camachat@xxxxxxxxx>]

On Thu, Sep 8, 2011 at 5:59 AM, Konrad Rzeszutek Wilk
<konrad.wilk@xxxxxxxxxx> wrote:
> On Wed, Sep 07, 2011 at 05:47:46PM -0700, Eric Camachat wrote:
>> Hi,
>>
>> I am porting our drivers to XEN's PV domU (with PV PCI passthrouth), I
>
> Use the DMA API that Linux provides (I presume that is what you meant
> by PV DomU), and use the dma_alloc_coherent to set your regions.

That's what I thought before. We use a shared DMA region for multiple hardware.
Maybe I can dma_alloc_coherent for 1st and the others use the same region.
I will try it.

>
> Also pass in 'iommu=soft' on your Linux command line to enable the
> Xen SWIOTLB DMA system.
>
>> have to allocate a memory block and tell the hardware to access it.
>> But the hardware can address 32-bit only, so I want dedicate a region
>> of memory that below 2GB for the domU only.
>
> Uh, don't you mean 4GB? - 32bit is up to 4GB.

The hardware uses 32-bit addressing, but the system will crash if I
assigned above 2GB address to it.
So, 4GB from hardware spec, 2GB from my test. I am looking into that.

>> How do that in XEN?
>>
>> Thanks,
>> /Eric
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel
>

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel