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New Contributor I
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Retpoline and Skylake-X

Hello

 

I saw that Retpoline is not compatible with the Skylake processor and later generations

 

I have a 7980XE and Windows 10 1903

 

I would like to know why I have the same performance with Retpoline enabled in the registry as with the Spectre patch disabled (in the registry)

If I enable the Spectre patch in the bios, I have a drop in performance

 

Thanks

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Moderator
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Hello tistou, Thank you for posting in the Intel® Communities Support.

 

In reference to your inquiry, we will do further research on this topic in order to provide the most accurate assistance and specifications about the information you are requesting.

 

As soon as I get any updates, I will post all the details on this thread.

 

Regards,

Alberto R.

 

Intel Customer Support Technician

A Contingent Worker at Intel

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New Contributor I
77 Views

Hello Alberto R

 

Thanks so much for your help

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Moderator
77 Views

Hello tistou, You are very welcome, I just received an update on this matter.

 

We just wanted to confirm, is there any reason in particular why you are looking for this information?

Are you building a BIOS or working on engineering a platform?

Are you developing an application?

If that is the case, which Operating System are you planning to use?

 

Additionally, just t let you know, all the public information, including approved FAQ on this topic, is available in the links below:

https://www.intel.com/content/www/us/en/architecture-and-technology/side-channel-variants-1-2-3.html

https://www.intel.com/content/www/us/en/architecture-and-technology/side-channel-variants-3a-4.html

 

Regards,

Alberto R.

 

Intel Customer Support Technician

A Contingent Worker at Intel

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New Contributor I
77 Views

Hello Alberto R

 

Thanks for your reply

I just wanted to know why the function (registry key) for retpoline seems to work with my Skylake-X, while it looks like it does not work with Skylake processor and later generations (according to Intel information)

 

Thanks

 

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Moderator
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Hello tistou, Thank you very much for clarifying those details.

 

Perfect, we will continue with our research on this matter, as soon as I get more updates I will post all the information on this thread.

 

Regards,

Alberto R.

 

Intel Customer Support Technician

A Contingent Worker at Intel

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New Contributor I
77 Views

Hello Alberto R.

 

Thanks and waiting for your answer

 

Regards

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Highlighted
Moderator
77 Views

Hi tistou, You are very welcome, I just received another update about this topic.

 

Could you please let us know where are you getting that information from?

Is there any link from Intel® that we can check where we say "while it looks like it does not work with Skylake processor and later generations (according to Intel information)"?

 

Regards,

Alberto R.

 

Intel Customer Support Technician

A Contingent Worker at Intel

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New Contributor I
77 Views

Hi

 

Of course, a Microsoft article that says this

 

"Since Retpoline is a performance optimization for Spectre Variant 2, it requires that hardware and OS support for branch target injection to be present and enabled. Skylake and later generations of Intel processors are not compatible with Retpoline, so only Import Optimization will be enabled on these processors."

 

https://techcommunity.microsoft.com/t5/Windows-Kernel-Internals/Mitigating-Spectre-variant-2-with-Re...

 

That relates to this Intel document

 

https://software.intel.com/security-software-guidance/insights/deep-dive-retpoline-branch-target-inj...

 

Regards

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Moderator
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tistou, Thank you very much for sharing the links.

 

We will review the information in there and continue with our research.

 

As soon as I get any more information, I will post it on this thread.

 

Regards,

Alberto R.

 

Intel Customer Support Technician

A Contingent Worker at Intel

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Moderator
77 Views

tistou, I just received an update on this case.

 

Retpoline should be compatible with Skylake and newer processors as this is software.

 

Regarding the performance comparison, we just wanted to gather a few more details about the systems being used:

What is the model of motherboards?

What is the BIOS version of each of them? and BIOS version

What is the model of the Intel® Processor used for comparison (i9-7980XE vs ?)

What is the Operating System version? Please provide a list of the patches installed.

What is the name of the applications used to compare performance?

 

Regards,

Alberto R.

 

Intel Customer Support Technician

A Contingent Worker at Intel

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New Contributor I
77 Views

Thanks for your reply Alberto R

I do the tests only on my PC by modifying the registry keys (patch Spectre enabled vs patch Spectre disabled vs Retpoline enabled)

 

I use for CPU performance, CPU-Z benchmark (the most used for this) and Crystal Disk Mark for "storage"

My PC

 

motherboard : Asus Rampage VI Extreme (bios 1902, microcode 49)

CPU : 7980XE

OS: Windows 10 pro x64 (18362.387)

 

My question was mostly about the compatibility of Retpoline with recent CPUs (the links mentioned would indicate that it is no longer compatible since Skylake)

 

Thanks

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Moderator
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tistou, You are very welcome, thank you very much for sharing that information.

 

We will continue reviewing the case, as soon as I get another update I will post all details on this thread.

 

Regards,

Alberto R.

 

Intel Customer Support Technician

A Contingent Worker at Intel

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Moderator
77 Views

Hello tistou, I just received an update on this matter.

 

After reviewing the case, we can confirm that either the microcode (if up to date) or the Operating System will have mitigation against security issues. Please verify the IBRS link below to gather further details about this matter:

https://software.intel.com/security-software-guidance/insights/deep-dive-indirect-branch-restricted-...

 

Regards,

Alberto R.

 

Intel Customer Support Technician

A Contingent Worker at Intel

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New Contributor I
77 Views

Hello Alberto R

 

thanks for your reply

I did not understand the relationship with Retpoline

 

Best regards

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Highlighted
Moderator
77 Views

Hello tistou, Thank you for your response.

 

Basically what we are suggesting for this scenario is to keep the BIOS updated and to install all the Windows* updates.

 

If you have further questions, please let us know.

 

Regards,

Alberto R.

 

Intel Customer Support Technician

A Contingent Worker at Intel

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Moderator
77 Views

Hello tistou: I just wanted to check if the information posted previously was useful for you and if you need further assistance on this matter?

 

Regards,

Alberto R.

 

Intel Customer Support Technician

A Contingent Worker at Intel

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New Contributor I
77 Views

Hello Alberto R

 

I did not really get an answer if Retpoline was yes or not compatible with Skylake-X :)

 

Best regards

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Highlighted
Moderator
77 Views

Hello tistou, Thank you for your response.

 

Yes, Retpoline is fully compatible with Intel® Skylake-X Processors.

 

Regards,

Alberto R.

 

Intel Customer Support Technician

A Contingent Worker at Intel

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New Contributor I
77 Views

Hello,

 

Thanks so much for your reply 😉

 

Best regards

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