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Date: Mon, 19 Jan 2009 16:05:22 +0100
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/5] Add target memory mapping API
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To: qemu-devel@nongnu.org

Ian Jackson wrote:
> The interface when cpu_physical_memory_map returns 0 is strange.
> Normally everything in qemu is done with completion callbacks, but
> here we have a kind of repeated polling.

Check patch #2 ;)

>   typedef struct {
>     /* to be filled in by caller before calling _map: */
>     unsigned flags;
>     target_phys_addr_t addr, len; /* len is updated by _map */
>     /* filled in by _map: */
>     void *buffer;
>     /* private to _map et al: */
>   } CpuPhysicalMemoryMapping;
> 
>   void cpu_physical_memory_map(CpuPhysicalMemoryMapping*;
>       CpuPhysicalMemoryMapCallback *cb, void *cb_arg);
>     /* There may be a limit on the number of concurrent maps
>      * and the limit may be as low as one. */

Hmm, I'd like to see grant tables fit into this picture too.
Using flags (instead of is_write) for map requests we can handle that
too I think.  We need a flag indicating we are passing a grant handle
not a guest address, then we can stick the handle into addr (or make
that a union).

cheers,
  Gerd