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Re: [Xen-devel] How works Xen mmu ?

To: Sylvestre Gallon <syl@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] How works Xen mmu ?
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Wed, 2 Jun 2010 21:07:18 +0100
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On 18/05/2010 09:01, "Sylvestre Gallon" <syl@xxxxxxxxx> wrote:

> My need is to simply perform an identity mapping at 0xb8000 to allow
> my operating system to access the vga frammebuffer. So my first idea
> was to use HYPERVISOR_mmu_update like this :
> 
> mmu_update_t mmu;
> uint8_t *buf = (uint8_t *) 0xb8000;
> 
> mmu.ptr = 0xb8000 | MMU_MACHPHYS_UPDATE
> mmu.val = 0xb8000
> HYPERVISOR_mmu_update(&mmu, 1, NULL, DOMID_SELF);

You need to use MMU_NORMAL_PT_UPDATE command, passing a pointer to a pte
(pagetable entry) in mmu.ptr and the value to write to that pte in mmu.val.

 -- Keir



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