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Visitor
Visitor
9,832 Views
Registered: ‎05-12-2014

Bitstream encryption: cfg_aes_only bit is what for *exactly*?

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Hello,

 

does anybody know if cfg_aes_only bit is REQUIRED '1' if I want to boot encrypted bitstream from Platform Flash using eFUSE at Virtex6?

 

Or is it just an option and it is required just in case when I want to boot "encrypted bitstream only and nothing else"?

 

(Documentation seems to be a bit unclear at this point.)

 

Thank you

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Xilinx Employee
Xilinx Employee
17,127 Views
Registered: ‎07-31-2012

Hi,

 

This option means that the FPGA can only be configured using the AES key in the EFUSE register. I dont think it needs to be enabled to configured the encrypted bitstream. Check the screenshot below for the description of this.

 

aes.JPG

 

Thanks,
Anirudh

PS: Please MARK this as an answer in case it helped resolve your query.Give kudos in case the post guided you to a solution.

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Xilinx Employee
Xilinx Employee
17,128 Views
Registered: ‎07-31-2012

Hi,

 

This option means that the FPGA can only be configured using the AES key in the EFUSE register. I dont think it needs to be enabled to configured the encrypted bitstream. Check the screenshot below for the description of this.

 

aes.JPG

 

Thanks,
Anirudh

PS: Please MARK this as an answer in case it helped resolve your query.Give kudos in case the post guided you to a solution.

View solution in original post

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Scholar
Scholar
9,820 Views
Registered: ‎02-27-2008

It is not required to use this bit,

 

It is required if you ONLY want to configure with an encrypted bitstream, and disable all others.


For example state gambling laws sometimes require that the gambling machine may only load the correct program (bitstream) so as to prevent tampering.

 

That bit is often called the "one armed bandit" bit (as it gets used in slot machines).

 

 

Austin Lesea
Principal Engineer
Xilinx San Jose
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Visitor
Visitor
9,779 Views
Registered: ‎05-12-2014

Thanks Anirudh,

 

it makes sense, especially as there is an "_only" postfix. I read the doc, but with a bit different "comment" in Xilinx User Guide ug360 and I was missing some quantifier like "also" or "only" in the "Comments" section. But I agree, aes_only means AES in eFUSE register only and without the bit set, you can load anything else.

 

aes.png

 

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