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Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integ
From: |
Paul Brook |
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 22:05:34 +0000 |
User-agent: |
KMail/1.9.7 |
> By the time you consider the different combinations of targets & hosts,
> most of the opportunities for zero copy are eliminated anyway. Byte
> ordering and structure packing amd content differences mean that we can't
> do zero-copy except in the rare circumstance that the host & target
> match is all of these respects. The read & write buffers would still
> benefit from zero copy, but nearly everything else has to be touched
> anyway.
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.
I've no idea whether this overhead is important in practice though.
Paul
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, (continued)
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, Paul Brook, 2007/11/03
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, Thayne Harbaugh, 2007/11/05
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, Paul Brook, 2007/11/05
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, Thayne Harbaugh, 2007/11/05
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, Fabrice Bellard, 2007/11/07
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, Thayne Harbaugh, 2007/11/07
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, Paul Brook, 2007/11/07
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, Thayne Harbaugh, 2007/11/12
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, Fabrice Bellard, 2007/11/06
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, Stuart Anderson, 2007/11/06
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?,
Paul Brook <=
- Re: [Qemu-devel] RFC: x86_64 Best way to fix 'cast to pointer from integer of different size' problems?, Stuart Anderson, 2007/11/06