[Xen-devel] DMA understanding

[Abhinav Srivastava <abhinavs_iitkgp@xxxxxxxxxxx>]

Hi there,

I am trying to understand how an HVM guest domain performs its DMA operations, 
and how this DMA operations are intercepted by the Xen. I wanted to understand 
both the code path with and without Vt-d support (for intel processors). On 
looking inside the Xen code, I found that iommu code is inside the vmx/vtd/ 
directory only. By seeing the code, my understanding is that when Vt-d is 
enabled, iommu.c and dmar.c inside the vtd directory is the place to look for 
DMA operations. However, I do not understand which code path inside the 
hypervisor is getting used in case of Vt-d is disabled?  How does Xen intercept 
guest DMA operations in this case? I am using Xen 3.3 version for my project (I 
admit that it is very old version).

Any help would be appreciated.

Thanks,
Abhinav





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