Re: [Qemu-devel] [PATCH 2/2 v2][UPDATED] Direct IDE I/O

[Laurent Vivier]

Le mardi 18 décembre 2007 à 00:03 +0000, Paul Brook a écrit :
> 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.

Thank you for your comments.

I had some doubts on this patch too. I will not resend it.
I will resend only the first one corrected with comments from Fabrice
(malloc()/free()).

Regards,
Laurent
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