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Re: [Q] enabling FPU for vpe1

To: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
Subject: Re: [Q] enabling FPU for vpe1
From: "Kevin D. Kissell" <kevink@paralogos.com>
Date: Wed, 04 Aug 2010 08:26:52 -0700
Cc: linux-mips@linux-mips.org
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You can only set the TC's CU bits if the VPE to which the TC is bound has access to the coprocessor. See sections 8.2 andf 6.7 of the currently online spec, and read the MIPS MT Principles of Operation document, if you can find it.

On 08/04/10 03:14, Deng-Cheng Zhu wrote:
Thanks for looking into this.

I did do that. But the CU1 bit of TC#1 (in VPE#1) can not be set by
TC#0 or itself. Looks like VPE#1 is not seeing the FPU at all...


Deng-Cheng


2010/8/4 Kevin D. Kissell<kevink@paralogos.com>:
Check the MIPS MT spec.  If I recall correctly, it's possible to enable
access to the FPU by either VPE by setting the right bits while the
processor is in the MT configuration mode.

Deng-Cheng Zhu wrote:
Hi,


I'm working on a 34Kf CPU. I understand that only one TC can use the
FPU at any given time.

My question is: If a TC is attached to the 2nd VPE (i.e. VPE1), can I
enable FPU for it?

I experimented on this, but failed to do it. Am I missing something?


Thanks

Deng-Cheng





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