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Windows Phone 7 emulator

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  • User profile image
    JoshRoss

    Has anyone noticed that the emulator is very quick? I'd be interested to see what the devs did to make it so speedy. -Josh

  • User profile image
    kettch

    @JoshRoss:I believe it's a real VM, so it runs as close to the hardware as possible. Obviously that's an inadequate explanation, so I also would like to hear from the team who built it.

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    Cream​Filling512
  • User profile image
    dahat

    @CreamFilling512:Um... not quite.

    The WP7 emulator JITs the app code from IL to x86, without any kind of intermediate ARM step... as was the (sort of) the case with the pre-WP7 emulator which emulated an ARM instruction set on top of an x86 CPU.

    The old way was needed as you could run native or managed within the emulator... I'd wager that the WP7 one could not be used as is if you were an OEM who was testing out some native code extensions.

  • User profile image
    Minh

    ,dahat wrote

    @CreamFilling512:Um... not quite.

    The WP7 emulator JITs the app code from IL to x86, without any kind of intermediate ARM step... as was the (sort of) the case with the pre-WP7 emulator which emulated an ARM instruction set on top of an x86 CPU.

    The old way was needed as you could run native or managed within the emulator... I'd wager that the WP7 one could not be used as is if you were an OEM who was testing out some native code extensions.

    From the description:

    * A CPU emulator that executes the ARM instruction set by JIT-compiling to x86

    It does sound like a ARM VM... so IL is JIT'ted to ARM instructions... which is JIT'ted to x86

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    Dr Herbie

    One reason that the emulator is fast is that it's using your full CPU, and not the CPU speed of the actual device; you have to test on a real device to ensure performance is adequate.

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    dahat

    ,Minh wrote

    It does sound like a ARM VM... so IL is JIT'ted to ARM instructions... which is JIT'ted to x86

    Did you look at the date on the linked to VM? July... 2006.

    I not recall which video it was (or even if it was an internal video), but the vibe that was given WRT some of why WP7 emulator is so much faster than the old one what I described above.

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    PerfectPhase

    In several videos/podcasts, I've heard WP7 devs mention how the WP7 build for the emulator is actually compiled as x86.

    Actually if you read:

    http://msdn.microsoft.com/en-us/library/ff402563%28v=VS.92%29.aspx

    http://msdn.microsoft.com/en-us/library/ff402567(v=VS.92).aspx

    Both mention Hardware-assisted virtualization, basically, it seems that it is closer to VMware Workstation/VirtualPC than a traditional emulator.

     

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