Core Duo Power Sapping Bug is Microsoft Issue

illusoryphoenix writes "A few weeks ago, Tom's Hardware noted a significant reduction in battery life of the Core Duo processors it tested when USB devices were inserted. Intel claimed that Microsoft had a bug in their USB drivers, while Tom's Hardware was unable to reproduce the same result for any of the other Pentium M microarchitecures. This issue has finally been publicly confirmed by Microsoft to be a USB driver problem which keeps the processor from entering advanced sleep states."

anandtech test

[Dionysus]

According to some testing over at anandtech [anandtech.com], problem was in the way Windows XP polls USB2 devices.

Tom's was wrong

[jamesl]

AnandTech has an in depth analysis. Like most things, the answer can't be found in a headline.
http://www.anandtech.com/mobile/showdoc.aspx?i=269 3/ [anandtech.com]

We've spent almost the past two weeks performing non-stop battery life testing on five notebooks with up to 4 different USB devices, testing theories, trying to pinpoint exactly what causes this problem and testing Microsoft's fix. What follows is the process that we went through in our labs when faced with this strange bug.

Re:Oh My God!

[evilgrug]

"There's a driver glitch with brand new hardware!!! "

Actually it affects Pentium Ms as well, according to Anandtech.

"It's already been two weeks and they haven't fixed it yet!!"

Microsoft first identified the issue and published a Knowledgebase article July 12, 2005. That's a little more than 2 weeks.

In fact, the regedit quickfix they're recommending was also published on that date ... meaning they still haven't resolved it 7 months later.

Re:Oh My God!

[tpgp]

I know that you're joking, but I have to reply to the serious parts of your post.

There's a driver glitch with brand new hardware!!!

From the TFA

When a peripheral device was connected to a USB (universal serial bus) 2.0 port, the notebook's battery life plunged at a greater rate than would normally be expected from the use of a peripheral such as a mouse or storage key.

Nope, not new hardware. USB is not new. The core duos just made the problem more obvious.

It's already been two weeks and they haven't fixed it yet!!
From the TFA

Microsoft published a Knowledge Base article on the subject in July 2005, but made that information available only to PC vendors and partners, a company representative said in a statement.

So, its actually been over six months and they haven't fixed it yet.

As usual, Microsoft waits for an issue to become public before bothering to fix it.

Re:Tom's was wrong

[Anonymous Coward]

The correct link [anandtech.com]

Here's the fix...

[altheusthethief]

Important This article contains information about how to modify the registry.

Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 (https://premier.microsoft.com/kb/256986/ [microsoft.com] [microsoft.com]) Description of the Microsoft Windows registry

SYMPTOMS
Consider the following scenario. You install Microsoft Windows XP Service Pack 2 (SP2) on a portable computer. Then, you connect a USB 2.0 device to the computer. In this scenario, the computer uses its battery power more quickly than you expect.

CAUSE
Windows XP SP2 installs a USB 2.0 driver that initializes any connected USB device. However, the USB 2.0 driver leaves the asynchronous scheduler component continuously running. This problem causes continuous instances of memory access that prevent the computer from entering the deeper Advanced Configuration and Power Interface (ACPI) processor idle sleep states. These processor idle sleep states are also known as C states. For example, these include the C3 and C4 states. These sleep states are designed, in part, to save battery power. If an otherwise idle portable computer cannot enter or maintain the processor idle sleep states, the computer uses its battery power more quickly than you expect.

RESOLUTION
Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method.

These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved.

Modify the registry at your own risk. To resolve this problem, add the EnIdleEndpointSupport entry to the USB registry key.

To do this, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate, and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\USB

Note If the USB subkey does not exist, create it. To do this, follow these steps:

a. Select the Services key. On the Edit menu, point to New, and then click Key.
b. Type USB in the New Key #1 box to name the new key "USB."
3. Right-click USB, point to New, and then click DWORD Value.
4. In the New Value #1 box that appears, type EnIdleEndpointSupport, and then press ENTER.
5. Right-click EnIdleEndpointSupport, and then click Modify.
6. In the Value data box, type 1, leave the Hexadecimal option selected, and then click OK.
7. Quit Registry Editor.

STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

APPLIES TO
Microsoft Windows XP Service Pack 2, when used with:
Microsoft Windows XP Professional
Microsoft Windows XP Home Edition

Re:BIOS Fix?

[ecuador_gr]

Ok, I might be overboard here, but something does not feel right. MS does confirm that it is their usb driver's fault, but a possible solution would be a BIOS upgrade??? How is not a Windows update able to fix an MS driver bug?
But if it is not really a driver bug, as the BIOS statement would indicate, why on earth would MS cover for anybody?

It does not make sense! If Chewbacca lives on Endor, you must acquit!

Re:anandtech test

[diegocgteleline.es]

In the Linux kernel Dave Jones also found [livejournal.com] a power consumption problem with USB, but it seems (to me) that the USB spec is just f*cked up - i wonder if this microsoft issue is related.

Re:Here's the fix...

[akac]

If you read the article, you'd also see that this "fix" also caused stability issues and didn't work after coming out of sleep.