show expected and problematic output produced by deviceQuery in GPU docs

[boegel]

showing output in case it doesn't work is useful for searching purposes...

[ocaisa]

This shouldn't actually happen though, because of the Lmod guards the only scenario I can see where you would reach this is where you are using a container and the system drivers are too old

[boegel]

I triggered it by cleaning out the host_injections directory after loading the module.

I agree it's very unlikely that it happens, but we should mention it in the docs regardless, if only to let people easily find this page when searching for error messages.

[ocaisa]

My concern here is that the placement here makes it seem like it not working is likely, but reaching this message is actually very unlikely

[ocaisa]

Maybe a little box saying What does it look like if the command fails?

[casparvl]

Currently, this only treats testing if you can run CUDA-enabled software from EESSI. Maybe we can also include a small instruction for testing if building new CUDA software on top of EESSI works properly. Something like this:
First, create a file hello_cuda.cu with the contents

#include <stdio.h>

__global__ void helloCUDA()
{
    printf("Hello, CUDA!\n");
}

int main()
{
    helloCUDA<<<1, 1>>>();
    cudaDeviceSynchronize();
    return 0;
}

Then

module load CUDA/<some_version>
nvcc -o hello_cuda.cu -o hello_cuda
chmod u+x hello_cuda
./hello_cuda 

[casparvl]

And mention they should test this for each version of CUDA they installed in host_injections

[boegel]

Makes sense, but that should be done in a separate PR?

[casparvl]

If you want, sure. I won't block this one over it :) Although I would consider it to be an integral part of "Testing the GPU support" to be honest :)

[ocaisa]

I don't see it as so integral if we are focused on software consumers, it's only integral if you want to do development-type work

[ocaisa]

Suggested change

	If the `deviceQuery` command can not access your GPU, you will see an error message like:
	```
	cudaGetDeviceCount returned 35
	-> CUDA driver version is insufficient for CUDA runtime version
	Result = FAIL
	```
	```
	!!! note "What if the `deviceQuery` command fails?"
	If the `deviceQuery` command cannot access your GPU, you will see an error message like:
	```
	cudaGetDeviceCount returned 35
	-> CUDA driver version is insufficient for CUDA runtime version
	Result = FAIL
	```