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Message-ID: <42075FC4.70700@bellard.org>
Date: Mon, 07 Feb 2005 13:32:04 +0100
From: Fabrice Bellard <fabrice@bellard.org>
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Subject: Re: [Qemu-devel] ARM: Adding Maverick FPU support
References: <1107544087.23911.8.camel@jmcmullan>
	<200502042200.32185.paul@codesourcery.com>
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To: qemu-devel@nongnu.org

Paul Brook wrote:
> On Friday 04 February 2005 19:08, Jason McMullan wrote:
> 
>>So, I'm working on an emulation environment for the Cirrus Logic EP93xx
>>processors with the Maverick Crunch(tm) FPUs.
>>
>>What files do I need to touch to add support for these instructions?
> 
> 
> At minimum target-arm/op.c, target-arm/translate.c, and target-arm/cpu.h.
> 
> Note that that FPA is implemented differently. I uses the same emulator as the 
> linux kernel, hooked up to the undefined instruction interrupt. I wouldn't 
> advise doing this as performance is really awful. It's approximately 2x 
> slower than target soft-float, and I guess about 20x slower than a native 
> implementation.

Just to give more information, the idea was not to integrate the FPA 
emulation in the CPU itself because I believed it was mostly implemented 
as a software FPU. The real directory of FPA should be 
qemu/linux-user/arm/nwfpe and _not_ qemu/target-arm/nwfpe. I left it in 
target-arm because of the CVS legacy...

Now if real ARM FPUs are implemented, I agree they should go in op.c and 
translate.c (an helper.c can be added too). There must be a way to 
disable it so that the exact emulated ARM CPU core can be selected with 
a command line option.

Fabrice.