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Re: [Xen-devel] Question about alignment check in sh_x86_emulate_write

To: "Su, Disheng" <disheng.su@xxxxxxxxx>
Subject: Re: [Xen-devel] Question about alignment check in sh_x86_emulate_write
From: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Date: Tue, 4 Dec 2007 12:43:34 +0000
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At 20:38 +0800 on 04 Dec (1196800681), Su, Disheng wrote:
> In in sh_x86_emulate_write:
>       if ( vaddr & (bytes-1) )
>               return X86EMUL_UNHANDLE;
> I met a problem the vaddr is not aligned on word or dword, but have to
> emulate it. 

Have you got an OS that does unaligned writes to its pagetables?
Exciting!  What is it doing?

> I am wordering about the reason for this check. Is it safe to get rid of
> it?

Not really.  Among other things, self-aligned writes never cross page
boundaries.

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Citrix Systems.
[Company #5334508: XenSource UK Ltd, reg'd c/o EC2Y 5EB, UK.]

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