Re: [Xen-devel] [PATCH] VMX support for MMIO/PIO in VM8086 mode

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 2 Apr 2005, at 07:49, Leendert van Doorn wrote:

> Memory mapped and port I/O is currently broken under VMX when the
> partition is running in VM8086 mode. The reason is that the instruction
> decoding support uses 32-bit opcode/address decodes rather 16-bit
> decodes. This patch fixes that. In addition, the patch adds support for
> the "stos" instruction decoding because this is a frequently used way
> to clear MMIO areas such as the screen.
>
> As an aside, vmx_platform.c should really reuse x86_emulate.c as much
> as possible.
The memory-fault emulator needs proper support for 16-bit addressing 
and vm86 mode, which won't be hard to hard. I also need to pull the 
privileged-op emulator out of traps.c, and abstract out the action 
parts of it (e.g., actual move to/from CR, move to/from I/O port) in 
the same way I abstracted memory accesses in the mem-fault emulator.
There's less of a win in sharing the priv-op emulator since it is so 
much simpler, but it should still clean up the code a bunch.
 -- Keir


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