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From: Kumar Gala <galak@kernel.crashing.org>
To: Michael Neuling <mikey@neuling.org>
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Subject: Re: [PATCH 5/9] powerpc: Introduce VSX thread_struct and CONFIG_VSX
Date: Wed, 18 Jun 2008 14:35:30 -0500
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Cc: linuxppc-dev@ozlabs.org, Paul Mackerras <paulus@samba.org>
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On Jun 17, 2008, at 7:47 PM, Michael Neuling wrote:

> The layout of the new VSR registers and how they overlap on top of the
> legacy FPR and VR registers is:
>
>                   VSR doubleword 0               VSR doubleword 1
>           
> ----------------------------------------------------------------
>  VSR[0]  |             FPR[0]             
> |                              |
>           
> ----------------------------------------------------------------
>  VSR[1]  |             FPR[1]             
> |                              |
>           
> ----------------------------------------------------------------
>          |              ...               
> |                              |
>          |              ...               
> |                              |
>           
> ----------------------------------------------------------------
>  VSR[30] |             FPR[30]            
> |                              |
>           
> ----------------------------------------------------------------
>  VSR[31] |             FPR[31]            
> |                              |
>           
> ----------------------------------------------------------------
>  VSR[32] |                              
> VR[0]                            |
>           
> ----------------------------------------------------------------
>  VSR[33] |                              
> VR[1]                            |
>           
> ----------------------------------------------------------------
>           
> |                              ...                             |
>           
> |                              ...                             |
>           
> ----------------------------------------------------------------
>  VSR[62] |                              
> VR[30]                           |
>           
> ----------------------------------------------------------------
>  VSR[63] |                              
> VR[31]                           |
>           
> ----------------------------------------------------------------
>
> VSX has 64 128bit registers.  The first 32 regs overlap with the FP
> registers and hence extend them with and additional 64 bits.  The
> second 32 regs overlap with the VMX registers.
>
> This patch introduces the thread_struct changes required to reflect
> this register layout.  Ptrace and signals code is updated so that the
> floating point registers are correctly accessed from the thread_struct
> when CONFIG_VSX is enabled.
>
> Signed-off-by: Michael Neuling <mikey@neuling.org>
> ---

Is VSX mutually exclusive with altivec/fp?  is there a MSR bit for it?

- k