Implementing a make command

Martijn van Oosterhout kleptog at
Sun Feb 17 16:50:18 EST 2002

On Sun, Feb 17, 2002 at 04:20:18PM +1100, Michael Still wrote:
> On Sun, 17 Feb 2002, Simon Fowler wrote:
> I was hoping for a userland only solution, because this strikes me as
> being a lot easier to debug, and less likely to take my machine to a
> better place.

There was a library that trapped libc calls that tried to implement various
userspace filesystems. Dunno what happened to that.

> I wrote a three line mount program (just says hello in main()), and put it
> in /usr/local/bin (the same location as smbmount). When I try a mount -t
> mikal blah /tmp/blah I get a message saying 'mikal' isn't supported by the
> kernel.

Ofcourse, mount pretty much copies the arguments straight to the kernel. And
the kernel knows nothing about that filesystem. So in that sense it does
need to be in the kernel.

> Does this imply that it is impossible to have a userland only filesystem?

You do need at least some kernel intervention. However, I strongly recommend
UML (User Mode Linux). It allows you to run a kernel in userspace, meaning
that if you kill something, you don't take your machine with it. You can
also gdb your kernel module without killing anything.

Martijn van Oosterhout <kleptog at>
> Terrorists can only take my life. Only my government can take my freedom.

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