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[[!template id=project

title="Userspace file system and device driver code sharing"


[Antti Kantee](

duration="3 months"

As is well-known, [puffs(3)]( is the NetBSD userspace file system framework. It provides support for implementing file servers in userspace. A lesser known "cousin" of puffs is the Pass-to-Userspace Device, or [pud(4)]( framework, which provides support for implementing character and block device servers in userspace. Both use [putter(9)]( for transmitting requests to and from the kernel.

Currently, puffs includes a userspace support library: libpuffs. It provides two facets:

* file system routines and callback interface
* generic parts, including kernel request handling

On the other hand, pud is without a userspace support library and servers talk with kernel directly with `read()` and `write()`.

The goal of the project is to modify libpuffs into a generic library which pud and puffs can share, and provide libpuffs and libpud built on this base. The submission should include a rough analysis of the source modules of libpuffs and what is going to happen to them during the project.

This project is fairly straightforward, but involves a reasonable amount of work. Plenty of [documentation]( exists to make the learning curve manageable. This project is an excellent opportunity to practise getting your hands dirty with real world systems.

[[!tag gsoc]]

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