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Date: Tue, 6 Nov 2007 17:19:40 -0500 (EST)
From: Stuart Anderson <anderson@netsweng.com>
Subject: Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from
	integer of different size' problems?
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To: Paul Brook <paul@codesourcery.com>
Cc: qemu-devel@nongnu.org

On Tue, 6 Nov 2007, Paul Brook wrote:

> If you're not careful you get double-copying. Once copying the struct from
> guest to host space, and then again when converting layout/endianess.

Yes, it would be easy to do that by mistake. The approach that has been
taken has been to use typed copy_*_user_<type>() routines for the structs
instead of using a seperate untyped copy_*_user() followed by a
convert_<type>() routine. The copy_*_user_<type>() routines do the copy
and convert in a single step.

This will never be as fast as an optimized buffer copy, but it will also
not be as slow as having seperate routines.



                                 Stuart

Stuart R. Anderson                               anderson@netsweng.com
Network & Software Engineering                   http://www.netsweng.com/
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