From: Stuart Anderson <anderson@netsweng.com>
To: Paul Brook <paul@codesourcery.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?
Date: Tue, 6 Nov 2007 17:19:40 -0500 (EST) [thread overview]
Message-ID: <Pine.LNX.4.64.0711061715070.17870@trantor.stuart.netsweng.com> (raw)
In-Reply-To: <200711062205.34944.paul@codesourcery.com>
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/
1024D/37A79149: 0791 D3B8 9A4C 2CDC A31F
BD03 0A62 E534 37A7 9149
prev parent reply other threads:[~2007-11-06 22:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-03 17:26 [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems? TJ
2007-11-03 17:52 ` Paul Brook
2007-11-05 19:51 ` Thayne Harbaugh
2007-11-06 1:05 ` Paul Brook
2007-11-06 2:00 ` Thayne Harbaugh
2007-11-07 19:18 ` Fabrice Bellard
2007-11-07 20:59 ` Thayne Harbaugh
2007-11-07 23:02 ` Paul Brook
2007-11-12 16:42 ` Thayne Harbaugh
2007-11-06 20:05 ` Fabrice Bellard
2007-11-06 21:52 ` Stuart Anderson
2007-11-06 22:05 ` Paul Brook
2007-11-06 22:19 ` Stuart Anderson [this message]
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