Modding The Barton XP To A Barton MP

Dr. Jackie Lee writes "Don't have the budget for an AMD Opteron? There's always a cheaper alternative with AMD's current Barton processors. In this article, we'll show you how to run these new Barton XP processors in SMP mode."

Comments

Hmf

[BJH]

Yeah, great - mod your XPs to act like MPs.

Guess what? You can't guarantee they'll work - people on LKML have refused to help users who have done this, as it simply makes it impossible to determine whether problems are the fault of the kernel or of the CPU itself.

This is one for the overclockers who couldn't care less about stability, methinks...

Re:Hmf

[beuges]

This is one for the overclockers who couldn't care less about stability, methinks...

Or, maybe, its for those of us who can't afford the hugely expensive 'multiprocessor' chips, but would still like to be able to run a dual-processor system.

As a programmer, it's always a good idea to have access to a dual-processor system, because there are all sorts of lockups that just wont happen on a single-processor system, but will lock your program up on a multi-processor one. Having a hugely expensive system just to debug an application isn't feasible - if you're able to fool a 'single processor' chip into thinking it's a 'multiprocessor' one, then you've got an essential debugging machine at a fraction of the price

Re:Hmf

[cowbutt]

Er, no, because then you end up wondering whether it's your bug or a hardware problem.

A friend spent a long time debugging some maths in a game engine he's working on. First of all, he assumed it was his code, then after eliminating that possibility, assumed it was a gcc bug, then eventually found that the problem was caused by the motherboard's voltage settings being incorrectly documented and therefore he'd mistakenly configured it to supply the CPU with the wrong voltage.

--

Re:Hmf

[theLOUDroom]

Guess what? You can't guarantee they'll work - people on LKML have refused to help users who have done this, as it simply makes it impossible to determine whether problems are the fault of the kernel or of the CPU itself.

Bah. You don't know anything for sure, neither to these LKML people. They're just trying to eliminate unknow quantities from their debugging (not like I blame them). For all we know right now (being that the article is slashdotted) there is no difference between the XP and MP except a jumper setting. I honestly wouldn't be suprised if it's true. Why go through all the trouble to fab seperate chips when you can just use external jumpers?

This wouldn't be the first time someone could upgrade their hardware by connecting two contacts.

What really matters is determining if there is any actual difference between an XP and an MP. If there is none, then this isn't just for "the overclockers who couldn't care less about stability". There are plenty of others who would love to save $40/cpu.

Since you don't know either way. You're not really contributing much to the discussion. Yeah, without any testing I wouldn't use a modded chip for critical data, but it's not impossible to verify whether or not the modded chip is stable. "it simply makes it impossible to determine whether problems are the fault of the kernel or of the CPU itself" No, it doesn't. There's a simple solution. Test with both modded XPs and regular MPs.

What needs to happen is testing. Without that, we don't really know how useful this mod will be.

Re:Hmf

[afidel]

Actually it's bridges on the package that make the difference, AMD laser cuts the SMP bridges on Barton core cpus that are intended to be XP's, these can be either failed MP chips, or much more commonly they are just XP's that were never tested for SMP compliance because the extra testing would take time and additional testing equipment. The problems introduced by running SMP XP's are that the quality of connecting the bridges varies greatly and is never as good as the origional connection that was laser cut, and the fact that you may have a core that AMD already rejected because it failed to work correctly in their SMP tests.

Re:Possible DMCA violation?

[fadeaway]

You trade your warranty for the modification. Sounds fair to me.

There's no EULA for hardware.. yet..

Reasons for SMP

[lingqi]

not trolling, but a serious question, coming from a ex-SMP-user:

why SMP nowadays?

Most OS, including XP, is now reasonably stable to the point where multitasking, including buring a CD, while doing something else is OK. (not to mention that CD burners have buffer under-run protection *anyhow* nowadays) I know this because my laptop, which is a measly P3, can handle all of the multitasking I do, given that I have pumped up the amount of RAM.

If I was doing stuff for school / research, Mathematica, Matlab, Maple, Spice (ok not 100% sure on spice) are all single processor only. And to be honest, if you are running a 3-day simulation, you really don't want to be playing UT at the same time on the same machine ANYWAY, so that's kind of a moot point. (you should probably not be playing UT period during such times, but that's a time management story that i won't get into)

If I was doing real work like rendering stuff, I think real work deserves a real SMP system, i.e. with a warrenty.

I mean, SMP has a pretty hefty price overhead (motherboard, memory if you want ECC, and the extra CPU, heavy duty power supply, another set of heatsinks etc), not to mention that the motherboard / chipset technology is usually a few monthes to two years behind the cutting edge stuff...

so, what convincing reason do a person have for using SMP right now (especially a ghetto-rigged one)?

Re:Reasons for SMP

[Brento]

why SMP nowadays?

Sadly, there's still a lot of dog-slow apps. Example: ask Macromedia Dreamweaver MX to test a stored procedure with a hundred parameters, and it'll freeze for 30-90 seconds on all of the P4's I've tried it on, pegging the CPU at 100%. On dual-CPU boxes, that means you can still be productive with the other CPU, and do things like whine on Macromedia user groups while it runs.

SMP also helps a lot if your box is both a testbed and a design system: mine runs SQL Server, IIS, and I do my design on it, so while I'm working, there's a ton of processes running.

Don't get me wrong, I still buy the "real" SMP systems with warranties, but just pointing out why I'm doing it, and I'm not rendering.