third draft of docs

Author: claudia-lola

docs/eessi.md

@@ -1,9 +1,7 @@
 # EESSI Guide
 
 ## How to Load EESSI
-EESSI can be initialised using the following method.
-
-The EESSI environment is sourced (in a non-reversible way) by running:
+The EESSI environment can be initialise by running:
 ```[bash]
 source /cvmfs/software.eessi.io/versions/2023.06/init/bash
 ```
@@ -12,20 +10,20 @@ This is non-reversible because it:
 - Changes your `$PATH`, `$MODULEPATH`, `$LD_LIBRARY_PATH`, and other critical environment variables.
 - Sets EESSI-specific variables such as `EESSI_ROOT`.
 
-This is the recommended method because it:
-- Detects your CPU architecture and OS.
+However, it is the recommended method because it:
+- Detects system CPU architecture and OS.
 - Detects and configures GPU support.
 - Prepares the full EESSI software stack.
 - Sets up Lmod (environment module system).
 
-The [EESSI docs](https://www.eessi.io/docs/using_eessi/setting_up_environment/) offer another method to load EESSI, in addition to one above. The alternative method only initialises the Lmod module system and does not load a platform-specific setup. For these reasons, it is recommened to use the method detailed above.
+The [EESSI docs](https://www.eessi.io/docs/using_eessi/setting_up_environment/) offer another method to load EESSI. This alternative method only initialises the Lmod module system and does not load a platform-specific setup. For these reasons, it is recommended to use the method detailed above.
 
 Successful environment setup will show `{EESSI 2023.06}` at the start of your CLI.
 
-To deactivate your EESSI environment you can either restart your shell using `exec bash` or exit the shell by `exit`.
+To deactivate your EESSI environment you can either restart your shell using `exec bash` or exit the shell by running `exit`.
 
 ## GPU Support with EESSI
-To enable GPU support, you need a site-specific build that has CUDA enabled. For a guide on how to do this, please refer to [docs/image-build.md](../image-build.md).
+To enable GPU support, the cluster must be running a site-specific image build that has CUDA enabled. For a guide on how to do this, please refer to [docs/image-build.md](../image-build.md).
 
 ### Using GPUs
 All CUDA-enabled software in EESSI expects CUDA drivers in a specific `host_injections` directory.
@@ -51,10 +49,23 @@ export PATH=/usr/local/cuda/bin:$PATH
 #### Loading EESSI module for the GCC compiler
 
 Running `which gcc` with EESSI initialised should initially show a path `.../2023.06/compat...` which points to the compatibility compiler.
-It is important to load a `gcc` version that is compatible with the host's CUDA version:
+
+It is important to load a `gcc` version that is compatible with the host's CUDA version. This can be found by referring to the table below:
+
+To find your cuda version run `nvcc --version`
+| **CUDA Version**     | **Recommended GCC Module (EESSI 2023.06)**                          |
+|----------------------|---------------------------------------------------------------------|
+| CUDA 13.0            | GCC/12.3.0                                                          |
+| CUDA 12.3 – 12.5     | GCC/12.3.0 or GCC/12.2.0 (officially supports GCC 12.x)             |
+| CUDA 12.0 – 12.2     | GCC/12.2.0 (officially listed supported version)                    |
+| CUDA 11.4 – 11.8     | no matching GCC module in EESSI 2023.06                             |
+| CUDA < 11.4          | not supported                                                       |
+
+To load correct ESSI module run, substituing x for the compatible GCC version: 
 ```[bash]
-module load GCC/12.3.0
+module load GCC/12.x.0
 ```
+
 Running `which gcc` will now give a path `.../2023.06/software...` which is the full compiler provided by EESSI. This is what we want for CUDA builds.
 
 Now you can run `cmake` and `make` to compile CUDA using EESSI's `gcc`.