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RE: [Xen-devel][VTD] 1:1 mapping for dom0 exhausts xenheap on x86/32 wit

To: "Keir Fraser" <keir@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel][VTD] 1:1 mapping for dom0 exhausts xenheap on x86/32 with 4G memory
From: "Han, Weidong" <weidong.han@xxxxxxxxx>
Date: Fri, 28 Sep 2007 15:28:57 +0800
Cc: "Kay, Allen M" <allen.m.kay@xxxxxxxxx>
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Thread-topic: [Xen-devel][VTD] 1:1 mapping for dom0 exhausts xenheap on x86/32 with 4G memory
Keir Fraser wrote:
> alloc_domheap_page() instead of alloc_xenheap_page(), and use
> map_domain_page() to get temporary mappings when you need them. This
> costs nothing on x86/64, where all memory is permanently mapped. 

I already had a try to use alloc_domheap_page() instead of
alloc_xenheap_page(). It works on x86/64. But it doesn't work on x86/32.

> Or it is *very* reasonable to only support vt-d on x86/64 hypervisor.
> That's the configuration we care about by far the most, since 32-bit
> guests run fine on a 64-bit hypervisor, and of course all vt-d
> systems will be 64-bit capable. 
>  -- Keir
> On 28/9/07 06:26, "Han, Weidong" <weidong.han@xxxxxxxxx> wrote:
>> xenheap size is 9M on x86/32 xen, it's not enough to setup 1:1 page
>> tables for dom0. It causes dom0 cannot boot successfully. Setup 1:1
>> page table in domheap still might be a problem since the thinking is
>> to use the same 1:1 page table for both dom0 and PV domains.
>> Currently I think of two options: 1) go back to original method,
>> that's to say setup page table dynamically for dom0; 2) increase
>> xenheap size on x86/32. How do you think about? Thanks. 
>> Weidong

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