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Microsoft readies exFAT patents for Linux and open source

For years, Microsoft has profited from its FAT file system patents. Now the company is making it explicit that it's freeing its remaining exFAT patents for Open Invention Network members.

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For years, Microsoft used its patents as a way to profit from open-source products. The poster-child for Microsoft's intellectual property aggression were the File Allocation Table (FAT) patents. But the Microsoft of then is not the Microsoft of now. First, Microsoft open-sourced 60,000 patents of its patent portfolio and now Microsoft is explicitly making its last remaining FAT intellectual property, the exFAT patents, available to Linux and open source via the Open Invention Network (OIN).

Microsoft announced that it now loves Linux and "we say that a lot, and we mean it!  Today we're pleased to announce that Microsoft is supporting the addition of Microsoft's exFAT (Extended File Allocation Table) technology to the Linux kernel."

ExFAT is based on FAT, one of the first floppy disk file systems. Over time, FAT became Microsoft's files ystem of choice for MS-DOS and Windows. It would become the default file system for many applications. Microsoft extended FAT to flash memory storage devices such as USB drives and SD cards in 2006 with exFAT. Both FAT and exFAT are used in hundreds of millions of storage devices. Indeed, exFAT is the official file system for SD Card Association's standard large capacity SD cards.

Now, Microsoft states:

It's important to us that the Linux community can make use of exFAT included in the Linux kernel with confidence. To this end, we will be making Microsoft's technical specification for exFAT publicly available to facilitate the development of conformant, interoperable implementations. We also support the eventual inclusion of a Linux kernel with exFAT support in a future revision of the Open Invention Network's Linux System Definition, where, once accepted, the code will benefit from the defensive patent commitments of OIN's 3040+ members and licensees.

Specifically, according to a Microsoft representative, "Microsoft is supporting the addition of the exFAT file system to the Linux kernel and the eventual inclusion of a Linux kernel with exFAT support in a future revision of the Open Invention Network's Linux System Definition."

When Microsoft first started loosening its grip on Linux-related patents, Bradley Kuhn, president of the Software Freedom Conservancy, asked for "Microsoft, as a sign of good faith and to confirm its intention to end all patent aggression against Linux and its users, to now submit to upstream the exfat code themselves under GPLv2-or-late."

Microsoft isn't doing that. Instead, said a Microsoft representative, "We are supporting the inclusion of exFAT in the Linux kernel and to facilitate that, we are making Microsoft's technical specification for exFAT publicly available.  We will also support the eventual inclusion of a Linux kernel with exFAT support in a future revision of the OIN's Linux System Definition." But while "we are supporting the inclusion of exFAT in the Linux kernel, the code submission is being performed by other members of the community."

The Microsoft speaker added the company has "no on-going patent litigation involving exFAT."

Why is Microsoft doing this considering over the years it's made tens of millions from its FAT patents? Stephen Walli, Microsoft's principal program manager for Azure, explained at Open Source Summit Europe last year that "Open source changed everything. Customers have changed. Fifteen years ago, a CIO would have said, 'we have no open source, they would have been wrong, but that's what they thought.' Now, CIOs know open source's essential … Microsoft has always been a company by, of, and for developers. At this point in history, developers love open source."

Keith Bergelt, OIN's CEO, welcomed this news. "We're happy and heartened to see that Microsoft is continuing to support software freedom. They are giving up the patent levers to create revenue at the expense of the community. This is another step of Microsoft's transformation in showing it's truly committed to Linux and open source."

When the next edition of the Linux System Definition is released in the first quarter of 2020, any member of the OIN will be able to use exFAT without paying a patent royalty. Bergelt noted that membership in the open-source patent protection consortium is free for any company willing to share its patents with others. However, a company need not have patents to join the OIN. 

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