Google has begun work on a 64-bit version of Chrome for Linux, a move likely to whip Linux loyalists into a lather of excitement.

"The V8 team did some amazing work this quarter building a working 64-bit port. After a handful of changes on the Chromium side, I've had Chromium Linux building on 64-bit for the last few weeks," said Chrome engineer Dean McNamee in a mailing list message Thursday

V8 is Chrome's engine for running programs written in the JavaScript language common on the Web. Chromium is the open-source project behind Google's branded and supported Chrome browser, and McNamee shared instructions for programmers to build 64-bit Chromium.

Virtually all PCs today come with 64-bit processors from Intel or Advanced Micro Devices, but for desktop computing, 32-bit operating systems and software are common. The transition to 64-bit software is well under way--notably with Linux and Mac OS X--but the change isn't simple. In the browser world, for example, it can be problematic running a 64-bit browser with a 32-bit plug-in such as Adobe Systems' Flash, Microsoft's Silverlight, or Sun Microsystems' Java.

In 64-bit versions, programs can take advantage of larger amounts of memory, performance can benefit from extra storage spaces called registers on processors, and some mathematically intense computing tasks can run faster. But along with issues such as broken plug-ins, 64-bit software can hog more disk space, complicate programmers' testing and support chores, and often doesn't really run appreciably faster, so the transition isn't necessarily a top priority.

For example, Mac OS X already is most of the way through its 64-bit transition, but 64-bit Safari won't arrive until Mac OS X 10.6, aka Snow Leopard, which is due in coming weeks. Apple, by the way, says that JavaScript will run much faster on the 64-bit version of Safari.

But Linux fans, who offset their smaller numbers with higher technical proficiency and a fondness for programming, are champions of 64-bit software. They hammered Adobe until it released a 64-bit version of Flash Player for Linux, and now they're agitating for 64-bit browsers.

Indeed, a discussion emerged on Wednesday about why a 64-bit version of Firefox isn't a higher priority.

"Optimizations such as the Tracemonkey JIT engine (a just-in-time compiler for JavaScript) have yet not been implemented for x86-64, which means that the i686 build will be faster than the x86-64 build," among other reasons, replied Mozilla's Benjamin Smedberg.

Windows is another matter altogether for browser makers; although 64-bit Windows is a common option nowadays on new machines, the vast majority of existing ones are still using 32-bit Windows, and there are plenty of late adopters.

A 64-bit version of Internet Explorer ships with Microsoft's 64-bit versions of Windows, but Safari for Windows won't be available alongside the Mac OS X version when it debuts. The work to rebuild JavaScript engines for 64-bit chips applies to multiple operating systems, so producing a version for one operating system does help move a given browser to the others.

So what's standing in the way of 64-bit Chrome for Windows?

"Motivation," according to another message by Google's Marc-Antoine Ruel. Well, not just that. Google or others also need to work on the sandbox security mechanism and gyp programming tools, he said.