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Xen optimizations for fast packet I/O
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Grant Table problem mapping dom0 mem to domU #3

Open vitas-yuzhou opened 9 years ago

vitas-yuzhou commented 9 years ago

From xen devel mailing list :http://lists.xen.org/archives/html/xen-devel/2007-07/msg00787.html,

Dom0 memory cann't be mapped to domU. So did you change some xen code to mapping dom0 mem to domU? which version is your xen hypervisor?

jpemartins commented 9 years ago

Hi,

Sorry for the delay in response.

I believe that the issue pointed out in that email no longer applies in today's Xen.

No changes were made to hypervisor, but only to network backend and frontend. There are no issues in mapping Domain-0 memory to Domain-U.

vitas-yuzhou commented 9 years ago

which version is your xen hypervisor? 4.2 or 4.4 or other? which version is your linux kernel version for dom0?

jpemartins commented 9 years ago

Any version of Xen should work (mainly tested with 4.3 and 4.4) and linux kernel up to 3.14.

vitas-yuzhou commented 9 years ago

Hi, I have tested again with the same xen and kernel version, but failed. I think the reason is the domain-0 memory can not mapped to domain-U. And I write a simple test application about grant table, it exactly proves that my thoughts， i.e. the same application, make the memory from domain-U be mapped to domain-0, but mapped domain-0 memory to domain-U failed. I think the fundamental cause is that domain-0 is privileged domain.

vitas-yuzhou commented 9 years ago

I test with other way. I run xennet in driver domain, not domain-0(privileged domain). It runs successfully, and the memory of driver domain can be mapped to other domain-U. But the performance is very low, I am debugging, please give me some advise.