mod XP-M to Athlon 64?

[Pipeline]

I have read that there are only 2 differences between a mobile athlon and a 64-bit athlon (both are K8):
1) some cache in the xp-m is disabled
2) the 64-bit operations are disabled in the xp-m

Is it possible to mod the L2 bridge to re-enable that cache on an XP-M? I think this was done with Thorton -> Barton. Has anyone here heard of this being done on an XP-M?

How would one go about re-enabling the 64-bit operations? I can't imagine it could be done with a device driver. I don't think there is a bridge that enables/disables these.

Am I over-simplifying the differences between these chips, or is it possible that a mod from XP-M to 64 bit could be accomplished?

[CrowdAds]

[Dorsai]

Your over simplifing and mis-informed. The XP-Mobile is just a high quality Barton core Athlon XP. By high quality I mean it was hand picked because of its ability to run at low voltages, besides that it is a Barton. There are no unused cache, pipelines or features on the Mobile; the Mobile is a fully functional x86 chip and has nothing disabled.

The A64 is a K8 core, but heavily modified with extra components not found in the Athlon XP such as the 64 bit registers and other core optimizations. For all intents and purposes the A64 is a totaly different chip that reused the best components from the Athlon XP.

There is absolutely no way to convert an XP into a A64.

[mdzcpa]

Originally Posted by Dorsai

The XP-Mobile is just a high quality Barton core Athlon XP.

No, the new XP-M chips are K8 Semprons. Although I do not have an answer, Pipeline's question is quite valid.

[mdzcpa]

I found more information on one of the new XP-Ms. This is the info from my Laptop:

CPU-Z reads it as a Sempron, but Sandra reads it like this:

Model : AMD Opteron™ Processor Dublin 2800+
Model Number : 2800 (estimated)
Performance Rating : PR1203 (estimated)
Type : Low Power
Package : FC µPGA754
Multiplier : 4/1x
Minimum/Maximum Multiplier : 4/1x / 8/1x
Generation : G8
Name : MC Athlon 64 (K8 ClawHammer) 90nm 2GHz+ 1.45-1.55V
Revision/Stepping : C / 0 (746)
Stepping Mask : DH7-CG
Core Voltage Rating : 0.950V
Min/Max Core Voltage : 0.950V / 1.450V
Maximum Physical / Virtual Addressing : 40-bit / 32-bit
Native Page Size : 4kB


This XP-M 2800+ is definitely a K8.

[Pipeline]

Originally Posted by mdzcpa

I found more information on one of the new XP-Ms. This is the info from my Laptop:

CPU-Z reads it as a Sempron, but Sandra reads it like this:

Model : AMD Opteron™ Processor Dublin 2800+
Model Number : 2800 (estimated)
Performance Rating : PR1203 (estimated)
Type : Low Power
Package : FC µPGA754
Multiplier : 4/1x
Minimum/Maximum Multiplier : 4/1x / 8/1x
Generation : G8
Name : MC Athlon 64 (K8 ClawHammer) 90nm 2GHz+ 1.45-1.55V
Revision/Stepping : C / 0 (746)
Stepping Mask : DH7-CG
Core Voltage Rating : 0.950V
Min/Max Core Voltage : 0.950V / 1.450V
Maximum Physical / Virtual Addressing : 40-bit / 32-bit
Native Page Size : 4kB


This XP-M 2800+ is definitely a K8.

Yeah, I've seen lots of documentation that it's a K8.

Sandra reports mine as an Athlon 64 (K8 ClawHammer), too. In fact, when I was at the sisoft site about to download Sandra, they recommened that I download the 64-bit version. That's what first caught my attention.

CPU-Z reports mine as an Athlon 64, too. For a while I thought maybe my notebook was shipped with the wrong (and better) chip.

Does anyone know of any sites that might have a diagram of the bridges on the chip and an explanation of what the various configurations do? Any other info/suggestions would be greatly appreciated.

[k0NG0]

Enabling 64-bit would be pointless unless one is to run a 64-bit Linux system (or a beta version of Windows XP for iAMD64).

I would also think there's a valid reason for cache being disabled in these processors. My guess is that the disabled portion has failed tests and thus been binned to have that part disabled.

Also, Sandra reading it as an Athlon 64 it probably due to not being updated to recognize the chip, and defaulting to another name. If it reports the socket as 754, it sure wouldn't be an XP-M as they surely use the older Socket A (there are no Athlon XPs for the newer sockets).

[Pipeline]

Originally Posted by kONGO

Enabling 64-bit would be pointless unless one is to run a 64-bit Linux system (or a beta version of Windows XP for iAMD64).

Exactly.

Originally Posted by kONGO

I would also think there's a valid reason for cache being disabled in these processors. My guess is that the disabled portion has failed tests and thus been binned to have that part disabled.

To me, there is a valid reason. This is done all the time with products that they want to sell to the price/performance crowd. There has to be something about these chips that makes them perform a bit worse than the Athlon 64 or else the Athlon 64 couldn't be sold for so much more. This is done with pixel-pipelines in video cards and has been done before in Athlon-XPs (and sucessfully modded in both cases). It is probably expensive to do the R&D and change the manufacturing process to actually build these without the cache.

Originally Posted by kONGO

Also, Sandra reading it as an Athlon 64 it probably due to not being updated to recognize the chip, and defaulting to another name. If it reports the socket as 754, it sure wouldn't be an XP-M as they surely use the older Socket A (there are no Athlon XPs for the newer sockets).

I think you are right about Sandra not being updated. But the fact that it still shows up as a 64-bit athlon goes to show you that there are VERY similar elements in the 2 architectures.

[k0NG0]

K7 and K8 are quite different to begin with. But as there are Socket A Semprons I see no reason why AMD disabling certain K8 features and calling it an XP-M couldn't be true.

What I'm saying is this: to rebadge a K8 core as far down the chain as an XP-M, I would think there are some actual problems with it. I don't think AMD can afford to rebadge fully functioning parts when they are pretty much selling every Athlon 64 they can today. So, if the cache fails, call it a Sempron. If something else fails (the DDR controller, perhaps) you have a Socket A Sempron or, indeed, an XP-M...

At least that's my theory.

[mdzcpa]

Originally Posted by kONGO

Also, Sandra reading it as an Athlon 64 it probably due to not being updated to recognize the chip, and defaulting to another name. If it reports the socket as 754, it sure wouldn't be an XP-M as they surely use the older Socket A (there are no Athlon XPs for the newer sockets).

This is entirely incorrect.

There are indeed K8 Sempron chips labeled by marketed by AMD as XP-M chips. They are socket 754 and begin with the 2200+. Also included in the XP-M K8 socket 754 family is the XP 2600+, 2800+ , and 3000+.

Sempron K8 Chart

[k0NG0]

Further down:

Q: What are the features of the Mobile AMD Athlon XP-M processors based on the "Barton" core?

A: Each Mobile AMD Athlon XP-M processor has 640KB total cache (128KB L1 and 512KB of L2 cache) to enable improved multitasking and improved overall performance. Like all AMD mobile processors, these processors include AMD PowerNow! technology for extended system battery life.

The Sempron has 384kB total cache...

Edit: Ah, you edited your post and removed the FAQ quote... Anyway, as far as I can see, the Sempron isn't called an XP-M anywhere visible on the regular CPU pages on AMD's site...

[mdzcpa]

*sigh*

The Dublin core (castrated K8) is marketed as XP-M.

X Bit Labs

The company will also offer Athlon XP-M “Dublin” chip with the same specs for mobile market. The microprocessor will inherit architectural innovations of K8 family, but will not support 64-bit computing

Here you can clearly see the K8 Dublin core as the next XP-M.

AMD sneaks out 90nm core in 130nm chip

During the next half of the year, AMD is also set to ship 'Dublin' a version of the 130nm mobile chips shipped under the Athlon XP-M brand. ®

It doesn't get any clearer than this.

[mdzcpa]

And one more reference for good measure:

HP Puts New “K8-Based” Athlon XP-M into Action

AMD Athlon XP along with AMD Athlon XP-M processors for Socket 754 infrastructure are expected to be released in the third or the fourth quarter of the year. From micro-architectural standpoint the new Athlon XP chips are generally the same as AMD’s eighth generation processors: the new CPUs have single-channel PC3200 memory controller as well as SSE2 technology in addition to the tangibly more efficient architecture

Okay, I think we've established that the K8 Dublin core is indeed the next XP-M.

All that said, I doubt the nuetering to the Dublin core can be undone anyway

[Sierra_abx]

Originally Posted by Pipeline

Is it possible to mod the L2 bridge to re-enable that cache on an XP-M? I think this was done with Thorton -> Barton. Has anyone here heard of this being done on an XP-M?

I have not seen a close-up picture of the Mobile Semprons. But I know the standard Mobile A64's (Socket 754) do not have bridges like the old Mobile Socket-A chips. Below is a pic of a Mobile A64 3400+.

[Lucas_Maximus]

well I have seen articles that it is impossible to make a sempron 64 into a a64 chip.

[k0NG0]

Cool beans, mdzcpa, you've convinced me, bud.