Re: AMD errata 169

Quoting Eygene Ryabinkin <rea-fbsd_at_codelabs.ru>:

> Fri, Jun 26, 2009 at 05:23:36PM +0400, Stanislav Sedov wrote:
>> > I'd like to eliminate this as a cause of my problem
>> >
>> > It appears I can read the value.
>> >
>> > #kldload cpuctl
>> > #cpucontrol -m 0xc001001f /dev/cpuctl0
>> > MSR 0xc001001f: 0x00400000 0x00100008
>> >
>> > #cpucontrol -m 0xc001001f=0x0040000000100008 /dev/cpuctl0
>> >
>> > Causes an nfe0 watchdog timeout and a powerdown failed, so that's
>> > clearly a dumb thing to do.
>
> Hmm, if I am reading the thing properly, you're trying to set the
> register to it's current value, aren't you?

Yeah, I figured that was a safe test. If it worked my next question  
was 'which bit is bit 32, followed by how do I set DsNpReqLmt0?'

Since this locked the primary network card, I guess I'm not going  
anywhere with this.

>  I would expect the final
> value of MSR to be 0x00400001:0x00100008.  And you should also set
> F0x68[22:21] (Link Transaction Register) to 01b (one non-posted
> downstream request). F0x68 means "configuration register 0x68,
> function 0", so looks like you'll be playing with bus 0, device 24,
> function 0, pci0:0:24:0 for the pciconf(8).
>
> By the way, here's what I got for my Asus M2NPV-VM:
> -----
> $ cpucontrol -m 0xc001001f /dev/cpuctl0
> MSR 0xc001001f: 0x00400001 0x00000008
>
> $ pciconf -r pci0:0:24:0 0x68
> 0f20c820
> -----
> As you can see, workaround for #169 is applied.
>
>> > Would I be better off asking somewhere else?
>
> You can try to look for BIOS update the implements the fix for #169,
> but may be such version for your MB isn't available.

As stated elsewhere later BIOS have the fix (which is how I know about  
it) but break other stuff.

Thanks anyway, that was useful info.

>
>> BTW, is there description of this NB_CFG MSR register somewhere on the
>> net?
>
> Google helps:
>    
> http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/31116.pdf
>
>> I think that some bits of this register could have specific meaning
>> and it is not safe to write them.
>
> Hmm, generally, yes, but in this case, bit 32 is reserved too, so
> I would just try to left the current value of MSR untouched, but just
> turn on the needed bits.
> --
> Eygene
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-- 
ian j hart

-- 
ian j hart

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