Date: Mon, 10 Jan 2022 03:55:39 -0500 From: "John Ericson" <list@johnericson.me> To: freebsd-arch@freebsd.org Subject: Leveraging process descriptors for process creation without fork Message-ID: <af2e4b58-9947-710a-5b72-d237b6c62e80@JohnEricson.me>
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Hi, I have long been interested in seeing an alternative to fork+exec implemented in a real-world Unix OS. What I have in mind is: 1. Load an executable into a fresh new unscheduled process (we might call this an "embryonic" process) 2. Set file descriptors and other state on that process 3. Submit it to the scheduler I am far from the first person to think of this interface, of course. Since becoming interested in this, I have been referred to this paper[1], which very nicely describes the concept in detail, and also evaluates an all-userspace implementation of it. I must admit I first emailed the Linux mailing list about this.[2] The reception was positive, but the multitude of other features[3] supported in the relevant code makes refactoring it to elegantly implement both the existing and new interfaces a rather large task. I checked, and FreeBSD's fork and exec code is, surprise surprise, a great deal simpler, and therefore a better venue for demonstrating this feature's viability. Also, as I am interested in the feature in the context of efforts like Capsicum and CloudABI, FreeBSD is a natural starting point for cultural and historical reasons. I am under no illusion that, even with FreeBSD's comparative simplicity, I will have time to finish this project in the near future, but I hope it is still OK to discuss the merits of the idea itself. Thanks, John [1]: http://catern.com/rsys21.pdf [2]: https://lore.kernel.org/lkml/f8457e20-c3cc-6e56-96a4-3090d7da0cb6@JohnEricson.me/T/#m6be1994668e6f34837496c86f37f9fe52bfae990 [3]: Especially binfmt_misc, if anyone was curious
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