Kernel mode GPGPU usage

Question

Is it possible to run CUDA or OpenCL applications from a Linux kernel module? I have found a project which is providing this functionality, but it needs a userspace helper in order to run CUDA programs. (https://code.google.com/p/kgpu/)

While this project already avoids redundant memory copying between user and kernel space I am wondering if it is possible to avoid the userspace completely?

EDIT: Let me expand my question. I am aware that kernel components can only call the API provided by the kernel and other kernel components. So I am not looking to call OpenCL or CUDA API directly. CUDA or OpenCL API in the end has to call into the graphics driver in order to make its magic happen. Most probably this interface is completely non-standard, changing with every release and so on....

But suppose that you have a compiled OpenCL or CUDA kernel that you would want to run. Do the OpenCL/CUDA userspace libraries do some heavy lifting before actually running the kernel or are they just lightweight wrappers around the driver interface?

I am also aware that the userspace helper is probably the best bet for doing this since calling the driver directly would most likely get broken with a new driver release...

Answer 1

The short answer is, no you can't do this.

There is no way to call any code which relies on glibc from kernel space. That implies that there is no way of making CUDA or OpenCL API calls from kernel space, because those libraries rely on glibc and a host of other user space helper libraries and user space system APIs which are unavailable in kernel space. CUDA and OpenCL aren't unique in this respect -- it is why the whole of X11 runs in userspace, for example.

A userspace helper application working via a simple kernel module interface is the best you can do.

[EDIT] The runtime components of OpenCL are not lightweight wrappers around a few syscalls to push a code payload onto the device. Amongst other things, they include a full just in time compilation toolchain (in fact that is all that OpenCL has supported until very recently), internal ELF code and object management and a bunch of other stuff. There is very little likelihood that you could emulate the interface and functionality from within a driver at runtime.