Apr 29, 2004 (09:04 AM EDT)
Review: CoLinux Allows Windows, Linux To Share PC

Read the Original Article at InformationWeek

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Cooperative Linux is a set of device drivers and assorted snippets that, when installed, lets Linux run as a protected process under Windows. It comes from Israel, and if you believe the stories about it, it's the best thing since sliced challah.

The open source software, available from the coLinux web siteand SourceForge,is pretty impressive.

Does it live up to claims of being revolutionary? It's certainly innovative. Is Bill Gates losing sleep over this new threat to his Windows dominance?

Well, it's certainly innovative.

How does it compare with other products that allow you to run Windows and Linux on the same machine, such a VMWare and CygWin? It's too early to tell - coLinux is still beta - but coLinux is already significant faster than the other software.

Download and Installation
It's a small download, less than 2MB. It installs easily, although it's a bit unusual in that the interim result provides for a non-connected network connection as seen in the Control Panel. You need to have a boot image of a Linux system available. Following the installation instructions carefully, I grabbed a Debian system, and decompressed it into my new coLinux directory. Tweaks here and there, some simple edits to an XML file defining where that boot image resides, some rudimentary partition information, define how much memory to devote to Linux, and you're basically done. Click on the coLinux icon and you're running Linux. And Windows. On the same box. At the same time. Woo-hoo!

It was a perfectly painless installation. Once installed, booting Linux just involved double clicking on a Windows icon. Next came installing a network "card" - just a software driver installed using the "Add Hardware" wizard on my Windows XP system - configuring it, and letting it know how to use my existing DSL line for Internet Connection Sharing. Then some pings to make sure my connectivity was good, and with a few downloads I was using Mozilla under Linux and Microsoft Internet Explorer 6 under Windows. At the same time. On the same box.

I like this product. A lot.

Performance
When you first boot coLinux up, you're in a text-only environment. Download your favorite GUI and mouse about. I found the Windows text mode window very slow, but the performance with true Linux code was standard speed - seemingly no delay and everything ran normally and at the same speed as stand-alone Linux.

CoLinux was substantially faster than the same code under both VMWare and CygWin on the same box.

How it all works and how it compares, say, to VMWare's running of a virtualized Linux kernel is all supposition. based on some research and some guesswork. Neither VMWare nor CoLinux wants to give up the trade-secrets of exactly how they work.

Here's how coLinux works: It's not magic. With a rewrite of the Linux kernel, and some device driver rewrites, it just appears magical. It seems the Linux kernel runs entirely in protected mode (Ring 0) and speaks to the Windows kernel through a marshaling set of device drivers. There are likely some transitioning surprises with buffer overruns and the like: having a Linux API call to read a huge disk file into a too-small buffer causes some serious problems, but that is to be expected, and seems to only cause these problems in the error-producing window. Just reboot the Linux window, fix the problem, and keep going.