[mythtv-users] Question on 8GB of RAM. Was: 32 bit or 64bit???

diane mittnik dianemittnik at gmail.com
Mon Jan 19 10:02:07 UTC 2009


On 1/17/09, John Drescher <drescherjm at gmail.com> wrote:
> On Sat, Jan 17, 2009 at 12:47 AM, Francis Hartojo <fhartojo at gmail.com>
> wrote:
>> On Fri, Jan 16, 2009 at 2:48 PM, Larry Finger <Larry.Finger at lwfinger.net>
>> wrote:
>>> John Drescher wrote:
>>>
>>>> I forgot to say no problems at work with the 8GB M2N-E boards...

<snip>

>> What he said.  In my case, the problem isn't so much the >4GB RAM, but
>> the CPU itself and how it works in 64-bit.  Apparently, I'm running
>> into a rather well-known TLB bug with Phenom 9x00 Quad Core BE chips.
>> The motherboard (i.e., an Asus M3A) has a workaround switch in the
>> BIOS, so I switched that on.  Seems to help, but Live TV still
>> eventually freezes although not nearly as often and as easily.

Don't remember exactly where, maybe wikipedia, or other tech articles
on the AMD cpus, but the TLB bug was supposedly eliminated in the cpus
ending in 50, ie: 9550, 9750, 9850, 9950, 8450, 8650, 8750 (cpus
currently listed on pricewatch).  Also, I recall reading at least one
source other than Intel/AMD about the TLB bug with the source (don't
recall who) stating that most or all TLB bugs can be eliminated
through a BIOS update, along with a tech article also stating that the
AMD TLB bug was eliminated in affected cpus with a either a BIOS
update or through the workaround switch in the BIOS as the parent
states.  Once either the BIOS update (if there is one that is
different from the workaround) is installed/adjusted, there is no
longer a TLB bug.


>> Alternatively and quite strangely I can also make it more stable if I
>> limit the # of cores to 2 via the kernel "maxcpus=2" command-line
>> parameter.  I don't understand why this appears to be so.  There's an
>> article on Tom's Hardware about the third core in some AMD Quad Core
>> chips being bad, but I don't understand it's got to with TLBs.  One of
>> these days I'll post a more detailed summary of the problem on the
>> Ubuntu forum in case someone else runs into it.

Like to know further details on this, please update us here as well if possible

> The TLB bug was supposed to be almost impossible to hit. I am not sure
> you are hitting that.
> John

Agreed, if it's a 8x50 or 8x50 cpu it's not TLB, or if the TLB
workaround or BIOS update is used, not likely? or not? TLB?

Please let us know if this issue is resolved with a definitive cause

D.


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