Linux: Where to use packed structures

Not sure if the structure should be packed or not? When to use one vs the other? What is the default behavior? What do they do?

For answering these questions, please download this PDF tutorial.

Typically this stems from the question, "what is the size of this struct"?

struct test_A
{
char a;
int b;
char c;
} x;

PDF Download

Citation:
Gautam Bhanage, "Padding versus Packing in Embedded Systems Programming", Published online at www.bhanage.com. May 2020. [PDF]