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Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix

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On Mon, Oct 24, 2016 at 02:38:06PM +0300, sonofagun@openmailbox.org wrote:
> The patch is not equivalent to the original. As a result it behaves
> differently. To be specific, using dmesg I get the expected value from the
> affected MSR with the original patch. With the latest patch, patching of the
> MSR occurs after dmesg prints the MSR information. That is why I thought it
> did nothing.

Gah, that "show_msr" is crap - it gets issued too early and we can -
and we do - set MSRs later too. Oh and it prints only the BSP. I should
probably rip it out - there's msr-tools for that which is much better.

> rdmsr --all 0xc0011021 returns the expected results on all CPUs with both
> patches. I have the impression that the system boots slower because the fix
> is applied later compared to the original patch.

Could be - setting those bits 3 in 14 in that MSR is probably disabling
some hw features which may impact performance.

> Could you please use perf and tell me what values do you get at perf
> branch-misses right after boot on your ON-B0 box? Launching firefox with
> only one tab gives you similar numbers?

Sure, give me the exact command you're executing so that I can do it here.

> If you need anything more, feel free to ask.

Out of pure interest: do you remember how exactly you did reproduce this
issue?

Thanks.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.

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Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix sonofagun@openmailbox.org - 2016-10-21 18:20 +0200
  Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix Borislav Petkov <bp@alien8.de> - 2016-10-21 18:50 +0200
    Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix sonofagun@openmailbox.org - 2016-10-22 00:00 +0200
      Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix Borislav Petkov <bp@alien8.de> - 2016-10-22 01:10 +0200
        Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix sonofagun@openmailbox.org - 2016-10-22 13:20 +0200
          Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix Borislav Petkov <bp@alien8.de> - 2016-10-22 17:10 +0200
            Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix sonofagun@openmailbox.org - 2016-10-23 11:40 +0200
              Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix Borislav Petkov <bp@alien8.de> - 2016-10-23 12:00 +0200
                Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix sonofagun@openmailbox.org - 2016-10-23 19:10 +0200
                Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix Borislav Petkov <bp@alien8.de> - 2016-10-23 19:30 +0200
                Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix sonofagun@openmailbox.org - 2016-10-23 23:10 +0200
                Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix Borislav Petkov <bp@alien8.de> - 2016-10-23 23:40 +0200
                Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix Borislav Petkov <bp@alien8.de> - 2016-10-24 14:40 +0200
                Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix sonofagun@openmailbox.org - 2016-10-24 15:20 +0200
                Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix Borislav Petkov <bp@alien8.de> - 2016-10-24 19:20 +0200
                Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix sonofagun@openmailbox.org - 2016-10-24 22:50 +0200
                Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix Borislav Petkov <bp@alien8.de> - 2016-10-25 11:30 +0200
                Re: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix sonofagun@openmailbox.org - 2016-10-25 15:20 +0200

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