[eclipse-iceoryx#436] Document payload type restrictions

FAQ.md

@@ -1,5 +1,19 @@
 # Frequently Asked Questions
 
+## Encountered a SEGFAULT. What Kind Of Data Types Can Be Transmitted Via iceoryx2
+
+iceoryx2 stores all data in shared memory, which imposes certain restrictions.
+Only data that is self-contained and does not use pointers to reference itself
+is allowed. This is because shared memory is mapped at different offsets in
+each process, rendering absolute pointers invalid. Additionally, if the data
+structure uses the heap, it is stored locally within a process and cannot be
+accessed by other processes. As a result, data types such as `String`, `Vec`,
+or `HashMap` cannot be used as payload types.
+
+To address this, iceoryx2 provides shared-memory-compatible data types. You
+can refer to the [complex data types example](examples/rust/complex_data_types),
+which demonstrates the use of `FixedSizeByteString` and `FixedSizeVec`.
+
 ## How To Send Data Where The Size Is Unknown At Compilation-Time?
 
 Take a look at the

examples/README.md

@@ -1,7 +1,8 @@
 # Examples
 
-> [!IMPORTANT] The examples are not yet functional in all languages. Check the
-> list below to see what is already working!
+> [!IMPORTANT]
+> The examples are not yet functional in all languages. Check the list below to see
+> what is already working!
 
 ## Foundations of Communication in iceoryx2 Applications
 
@@ -40,6 +41,29 @@ intend. The service port factory allows you to fine-tune the settings and
 behavior of individual ports, giving you precise control over how they interact
 and exchange data.
 
+## Payload Type Restrictions
+
+> [!CAUTION]
+> iceoryx2 stores payload data in shared memory, which imposes the restriction that
+> the payload type must be self-contained and cannot use heap memory. Additionally,
+> internal pointers are not allowed because the shared memory is mapped at different
+> offsets in each process, making absolute pointers invalid and potentially leading
+> to segmentation faults.
+
+To address these limitations, we provide data types that are compatible with shared
+memory. For Rust, we offer:
+
+* `FixedSizeByteString`
+* `FixedSizeVec`
+
+For C++, we provide:
+
+* `iox::vector`
+* `iox::string`
+* `iox::list`
+
+These types are demonstrated in the complex data types example.
+
 ## Overview
 
 | Name                               | Language                                                                                                                                | Description                                                                                                                                                                                                     |