New Linux Kernel Patch: avoids Microsoft FAT file system patents

Article Title: New Linux Kernel Patch: avoids Microsoft FAT file system patents. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.

Microsoft recently accused TomTom of infringing its own FAT file system patent. This incident has had a significant impact on the open source sector, especially enterprise users who use Linux and FAT file systems, last week, the related personnel specifically released a new kernel patch for the Linux operating system. As this patch bypasses Microsoft's patents, after installing this patch, linux users can continue to use the operating system to operate the FAT file system without being accused by Microsoft.

TomTom is a manufacturer specializing in the production of portable navigation devices. Some of their GPS products have installed Linux operating systems based on the FAT file system. In February this year, Microsoft filed a lawsuit against the company, claiming that these GPS products of TomTom infringe on their own FAT file system patents. Currently, this file system is widely used in portable storage devices. USB flash drives, flash cards, and other products often use this file system.

TomTom, who was not willing to show weakness, then launched a counterclaim. However, after the final judgment in May, TomTom lost the case and was forced to remove content related to the FAT file system from their products.

However, the results of this decision made the legitimacy of the Linux operating system using the FAT file system very vague. Although Microsoft claims that it will not sue individual Linux users who use the FAT file system, it is a headache for companies that use the FAT file system and Linux operating system. Currently, there are not a few mobile devices using the Linux operating system, and these devices must be able to read the FAT format storage body.

The Linux Foundation claims that the best way is to discard the FAT file system and re-develop a new file format. In the long run, this proposal is of course very reasonable, but it is difficult for the Linux system to immediately give up its support for the FAT format, and the launch of the new patch can solve this problem.

Microsoft FAT patent issues are mainly concentrated on a patent named "Long and Short file name General namespace. In earlier versions, the MsDOS operating system only supported 11-character file names, namely the so-called "8.3" naming mechanism. To meet the downward compatibility requirements, the patent simultaneously allocates one short File Name Record item and multiple long file name record items to the file.

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The Linux patch released last week has changed the Linux operating system's method of processing the FAT file system. Now, Linux does not allocate long/short file name records for the same file at the same time. If the length of the file name is not more than 11 characters, the system will allocate only one short File Name Record item to the file. If the file name is more than 11 characters, the system will allocate only one long file name record item to this file, and fill in 11 invalid characters in the original short File Name Record item, in this way, the short file name record items of a long file name will be regarded as illegal by the operating system and will not be displayed.

The patch author explained: "Two patents related to Microsoft's VFAT file system use the method of allocating long/short file name record entries for the same file at the same time, however, our patch will only allocate one available File Name Record item to the same file."

After patching, the short file name record items of the original long file name will be filled with invalid characters. These invalid characters will be randomly generated. Instead of simply filling in a value of 0, because filling in specific numbers in these record items may cause Windows XP to crash, the random generation of invalid characters can be avoided as much as possible.

This is the second patch released by the patch author for the FAT patent incident. In the patch first released by the author, he completely abolished the long file name, the new patch is more practical and popular with users because it retains long file names.

Despite this, the Linux Foundation still believes that Microsoft's so-called FAT patent is illegal, and they just want to make some Enterprise Linux users try not to be harassed by Microsoft, the latter has even been dragged into a difficult lawsuit.