FlashCache at Facebook from 2010 to 2013 and beyond
1–10 of 16 posts
Re: FlashCache at Facebook from 2010 to 2013 and beyond
#2For reference, the FlashCache project and source code is publicly available on github: https://github.com/facebook/flashcache/
Re: FlashCache at Facebook from 2010 to 2013 and beyond
#3Too bad it is GPL v2. https://github.com/facebook/flashcache/blob/master/LICENSE
Re: FlashCache at Facebook from 2010 to 2013 and beyond
#4Too bad it is GPL v2. https://github.com/facebook/flashcache/blob/master/LICENSE
Why would the license matter for a kernel module? You know that the linux kernel is also GPL v2 right?
Re: FlashCache at Facebook from 2010 to 2013 and beyond
#5Too bad it is GPL v2. https://github.com/facebook/flashcache/blob/master/LICENSE
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Re: FlashCache at Facebook from 2010 to 2013 and beyond
#6How does flashcache compare to dm-cache / bcache, integrated into linux kernels 3.9 and 3.10?
The text mentions that it works as a device mapper module, so does it actually work with dm-cache?
The readme on github suggests that it targets older kernel versions, most of which look like versions that ship in RHEL & Ubuntu LTS.
Re: FlashCache at Facebook from 2010 to 2013 and beyond
#7Too bad it is GPL v2. https://github.com/facebook/flashcache/blob/master/LICENSE
Why would the license matter for a kernel module? You know that the linux kernel is also GPL v2 right?
How about the usual reason? Because it can't be pulled into non-GPL projects.
This is actually relevant, at least, to me. I've been porting Twitter's fatcache[1] to iOS, and wouldn't be if it was GPL'd. I haven't even looked at Facebook's code, due to the GPL license, which makes it—literally—unusable to me on iOS and Android.
Re: FlashCache at Facebook from 2010 to 2013 and beyond
#8Earlier quoted context omitted.
Why would the license matter for a kernel module? You know that the linux kernel is also GPL v2 right?
How about the usual reason? Because it can't be pulled into non-GPL projects. This is actually relevant, at least, to me. I've been porting Twitter's fatcache[1] to iOS, and wouldn't be if it was GPL'd. I haven't even looked at Facebook's code, due to the GPL license, which makes it—literally—unusable to me on iOS and Android. [1] https://github.com/twitter/fatcache
It's indeed terribly unfortunate that you can't take free software and make it nonfree.
Re: FlashCache at Facebook from 2010 to 2013 and beyond
#9Earlier quoted context omitted.
Why would the license matter for a kernel module? You know that the linux kernel is also GPL v2 right?
How about the usual reason? Because it can't be pulled into non-GPL projects. This is actually relevant, at least, to me. I've been porting Twitter's fatcache[1] to iOS, and wouldn't be if it was GPL'd. I haven't even looked at Facebook's code, due to the GPL license, which makes it—literally—unusable to me on iOS and Android. [1] https://github.com/twitter/fatcache
But it is kernel code. Would you expect it to be trivial to port a device mapper kernel module from Linux to Darwin? Seems like a bit of a stretch
Re: FlashCache at Facebook from 2010 to 2013 and beyond
#10Earlier quoted context omitted.
Why would the license matter for a kernel module? You know that the linux kernel is also GPL v2 right?
How about the usual reason? Because it can't be pulled into non-GPL projects. This is actually relevant, at least, to me. I've been porting Twitter's fatcache[1] to iOS, and wouldn't be if it was GPL'd. I haven't even looked at Facebook's code, due to the GPL license, which makes it—literally—unusable to me on iOS and Android. [1] https://github.com/twitter/fatcache
It is possible to make a legal argument that a Linux-specific device driver is in fact derivative of the Linux kernel code that it interacts with. If said argument is made, then no matter what the author of said code says, it may actually be forced to be GPL v2.
I am not a lawyer, and I have no real idea how likely said argument is to hold up in an actual court. It also seems unlikely that anyone would actually file a lawsuit about this sort of stuff. But if you want to be as careful as you can be, you won't go wrong if you use the GPL v2 on principle for a Linux device driver.
On this topic it is worth noting that Linus Torvalds has stated different seeming opinions at different times. In general as more and more of the Linux kernel has been made available to loadable modules, he's become less and less inclined towards the argument that they are not derivative works. See http://linuxmafia.com/faq/Kernel/proprietary-kernel-modules.... for a comparison of his views at two points in time. (I don't know his current views.)