Former Microsoft CEO Steve Ballmer once said, "Linux is a cancer".
He also said that open-source "should therefore be regarded as a violation of the public trust."
As years pass, Microsoft and the open-source community remain strong, with each having their own market. But in the 2005 and 2007, Microsoft submitted its Microsoft Community License and the Microsoft Permissive License to the OSI.
And later, Azure gave Microsoft the reasons to love rather to hate Linux.
Then the affair has gone further as the company announced that it has joined the Open Source Initiative (OSI) as a Premium Sponsor.
What this means, Microsoft joins the likes of Google, Facebook, IGM, HPE, AdblockPlus, GitHub and Heptio as top sponsors of the project. Other sponsors also include RedHat, The Linux Foundation, Mozilla and HP.
The move by Microsoft follows its previous move to become a Platinum member of The Linux Foundation, which is also a member of OSI.
According to Microsoft's director of open-source engineering Jeff McAffer, Microsoft's OSI membership is part of the company's developing relationship with open source.
OSI's announcement describes Microsoft's membership as its "most dramatic step" yet towards supporting the open-source software movement.
"This is a significant milestone for the OSI and the open-source software movement more broadly," said Patrick Masson, OSI general manager and board director.
"I don't think there could be any greater testament to the maturity, viability, interest, and success of open-source software than not only Microsoft's recognition, but also their support as a sponsor, as well as their participation as contributors to so many open-source projects and communities."
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With Microsoft sponsoring OSI, this is another sign that the company's attitude towards open source has changed.
Microsoft developers are the top contributors to GitHub and have worked with FreeBSD Foundation to support it on Azure. Microsoft has even open-sourced its Chakra JavaScript engine for its Edge web browser.
The company has also put several milestone, including the release of open-source .Net Core 1.0 in 2014, working with Canonical to bring Ubuntu to Windows 10 along with the Linux Subsystem for Windows 10, and open-sourcing Xamarin.
What's more, Microsoft co-founder, Bill Gates, admitted that he uses a smartphone with a Linux kernel and not a Windows Phone.