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Re: [Qemu-devel] [PATCH 2/2 v2][UPDATED] Direct IDE I/O
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] [PATCH 2/2 v2][UPDATED] Direct IDE I/O |
Date: |
Tue, 18 Dec 2007 00:03:48 +0000 |
User-agent: |
KMail/1.9.7 |
On Monday 17 December 2007, Fabrice Bellard wrote:
> 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.
In general it may also be unsafe to do async writes directly to guest memory
because you break the atomicity of loads/stores.
Paul