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[Xen-devel] address mapping between domains

To: <xen-devel@xxxxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] address mapping between domains
From: Zhiyi Huang <zhiyi6@xxxxxxxxxx>
Date: Tue, 8 Mar 2005 4:59:10 +1300
Delivery-date: Mon, 07 Mar 2005 16:18:59 +0000
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Hi, I am trying to figure out how address mapping is done for zero-copy I/O. Is 
it allowed by the hypervisor that a page allocated to domain0 (the privileged 
domain) is mapped to the address space of a domainU? So far it seems to be the 
other way around: a page from a domainU is mapped to the address space of 
domain0 when I/O requests are sent to domain0.

Another question is about the hypercall: update_va_mapping. It has three 
arguments: vaddr, val, flags. Can anyone kindly explain the meaning of them and 
how they are used in the hypercall? Actually I am puzzled why there is no 
machine page id as an argument, since the virtual address should be mapped to a 
machine page anyway when the page table is updated.

Thanks a lot.

Zhiyi from EPFL Switzerland

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