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Date: Tue, 18 Dec 2007 00:02:40 +0100
From: Fabrice Bellard <fabrice@bellard.org>
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Subject: Re: [Qemu-devel] [PATCH 2/2 v2][UPDATED] Direct IDE I/O
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To: Laurent Vivier <Laurent.Vivier@bull.net>, qemu-devel@nongnu.org

Laurent Vivier wrote:
> This patch enhances the "-drive ,cache=off" mode with IDE drive emulation
> by removing the buffer used in the IDE emulation.
> ---
>  block.c     |   10 +++
>  block.h     |    2 
>  block_int.h |    1 
>  cpu-all.h   |    1 
>  exec.c      |   19 ++++++
>  hw/ide.c    |  176 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
>  vl.c        |    1 
>  7 files changed, 204 insertions(+), 6 deletions(-)
> [...]

Unfortunately it is more complicated to write to the CPU memory. In
particular, specific action should be done when translated code is
present. A consistent API must include something like cpu_page_lock() /
unlock(). Look at cpu_physical_memory_rw() to see the various issues
which must be handled. Moreover, it would be better to add bus specific
APIs (at least for PCI), but I can accept a CPU memory API for now.

Fabrice.