Intel's next generation of Atom processors made headlines last week because it will completely eschew Linux support, but that wasn't the only detail about the new Clover Trail platform that came out of last week's Intel Developer Forum—the same power usage optimizations that make it incompatible with Linux also make it an interesting choice for Windows 8 tablets, and give us a peek at the power-saving tricks used in Intel's next-generation Haswell chips to boot.

Clover Trail basics

Slated to arrive in October, the Clover Trail SoC is a close relative of the Medfield platform that we've seen in Atom-powered smartphones like the Xolo 900—it uses the same 32nm CPU architecture (codenamed Saltwell), but is a dual-core rather than a single-core part and is paired with a more powerful GPU, a dual-core PowerVR SGX 544MP2 GPU that is said to be comparable to Apple's A5X in graphics performance.

We'll likely see Clover Trail in many of the first Windows 8 tablets, slotted in between the Windows RT devices at the low end and the low-power Ivy Bridge devices at the high end—Lenovo's ThinkPad Tablet 2 is said to use Clover Trail, as are several of the other laptop-like Windows 8 tablets introduced at this year's IFA. According by Intel, Clover Trail should enable these tablets to deliver ten hours of battery life and a month or so of standby time in an 8.5mm thick package that weighs about a pound and a half—comparable, in other words, to current 10" ARM-based tablets.

Power savings: the "active idle" system state revisited

The most interesting bits revealed about Clover Trail pertained to how it achieves these battery life numbers—in Intel's Haswell presentation, the company talked about a new system power state it dubbed "S0ix," also called "active idle." Unlike the traditional S3 and S4 (sleep and hibernate, respectively) states, a system in this S0ix state is still connected to the Internet, and Windows applications that use background task and push notification APIs can still retrieve data. System resume time is also said to be instantaneous, wasting less power than in the transition between sleep states.

Another power-saving feature, and one that is standard in basically all mobile devices these days, is hardware accelerated video and audio playback designed to offload these common tasks from the CPU to more power-efficient parts of the SoC. Clover Trail's GPU can decode 1080p MPEG4, H.264, and MPEG2 streams, and its audio offloading engine can be used to play HTML5 audio or audio from applications using the Windows Media Foundation or Windows Audio Session APIs—however, the audio engine is only available to applications from the Windows Store, and not to standard desktop applications.

The Clover Trail platform also supports other standard tablet amenities—magnetometers, accelerometers, gyroscopes, GPSes, NFC, and ambient light sensors are all supported, and the chip includes an image signal processor (ISP) that helps it process images and video taken with integrated cameras.

Conclusions and observations on the Linux situation

While Clover Trail's power usage technology will be interesting (and will give us some indication of how accurate Intel's lofty power usage numbers for Haswell chips are), the processor itself is going to sport performance that's not much faster than the Atoms that we've been seeing in netbooks for the last few years. Next year's Bay Trail platform—which will introduce quad-core chips, Intel's own in-house GPUs, and a major architectural upgrade to the Atom line—should prove to be a more interesting performer.

While Intel has played up the new chip's compatibility with Windows 8, it's worth noting that the lack of support for Linux in this particular Atom seems to me like an anomaly rather than the new normal. In its Haswell presentation, Intel made no mention of the S0ix power state being incompatible with non-Windows operating systems, saying only that the sleep state transitions would be "automatic" and "transparent to well-written software." It's also worth noting that Medfield SoCs, which are extremely similar to Clover Trail SoCs, run Android in smartphones without complaint.

I wouldn't expect this Linux support issue to affect future Atom chips, especially those used outside of tablets. Server chips are still on Intel's roadmaps for both its Atom and Core-series CPUs, and while lack of support for Linux on the desktop wouldn't have much of an impact on Intel's bottom line, putting the same restrictions on server chips would be a much larger problem. If anything, the Bay Trail Atom platform's switch away from PowerVR GPUs back to Intel's own in-house graphics products should improve Linux driver compatibility—we won't know anything for sure until the Bay Trail chips are nearer to launching, but I'd be very much surprised if they don't restore Linux compatibility to the lineup.

Listing image by Intel