diff --git a/docs/software/communication/cray-mpich.md b/docs/software/communication/cray-mpich.md
index e06880fd..be3adb8e 100644
--- a/docs/software/communication/cray-mpich.md
+++ b/docs/software/communication/cray-mpich.md
@@ -79,6 +79,15 @@ Cray MPICH may sometimes hang on larger runs.
 
 Performance may be negatively affected by this option.
 
+#### `"cxil_map: write error"` when doing inter-node GPU-aware MPI communication
+
+This error message is sometimes triggered by applications that use GPU Direct MPI calls when they trigger a bug in gdrcopy (a low-level library used to copy buffers between GPUs).
+Setting the following option will completely disable gdrcopy.
+Note that this has a performance impact for small message sizes, so it should only be enabled on a case-by-case basis.
+```bash
+export FI_CXI_SAFE_DEVMEM_COPY_THRESHOLD=0
+```
+
 ### Resolved issues
 
 #### `"cxil_map: write error"` when doing inter-node GPU-aware MPI communication