alt Hacker NewsNot to be too facetious but a great place for communicating with the kernel where there are a ton of other driver subsystems is... the kernel.
Possibly a good addition to the article would be parallel development of an lkm. I guess it wouldn't have that windows interop but I would also be interested to see how this driver would be implemented on Windows. If it's idk 10x as many lines in the kernel vs userspace, that's a great benefit to the userspace approach.
Replies
Arguably all these other subsystems shouldn't be in the Kernel either but that's a different topic :)
There are quite a few benefits to doing these things in userspace over the Kernel, not really necessarily just because of the code size:
- The code is much easier to write and debug, you just write code like you always would.
- Bugs don't have the possibility to taking down your entire system or introduce vulnerabilities
- Especially on Windows, everyone can do this without requiring an impossible to get driver signing certificate
In HFT user-space networking drivers have a long history - there is too much latency induced by switching from kernel to user space to handle networking.
> OpenOnload: A user-space network stack that intercepts socket calls to bypass the kernel network stack, accelerating standard socket operations for faster networking.
> Netmap: A framework providing a simple API for high-speed packet I/O in user space, bypassing much of the kernel overhead for efficient packet forwarding and filtering.
https://dysnix.com/blog/high-frequency-trading-infrastructur...
Driver signing is a killer issue on Windows; if you put your machine into dev/unsigned mode you get an ugly banner that can't be turned off.
Much easier to design the device to avoid that. E.g. by abusing USB-HID. The desktop USB missile launcher toy is USB HID, for example.