Saturday, May 23, 2020

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

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

Saturday, May 2, 2020

Linux: Kernel Stack Corruption

What do you do when you see a crash trace like this one?

-- snip --
task: ffffffc07d4d8000 ti: ffffffc07d4d4000 task.ti
PC is at 0xc72kf
LR is at 0xc72kf
pc : [<00000000000c70c0>] lr : [<00000000000c70c0>]
sp : ffffffc07d4d7920
x29: ffffffc07d4d7720 x28: ffffffc07d4d7a58
x27: 0000000000000001 x26: ffffffc07d477780
x25: 0000000000000001 x24: ffffffc00088f000
 [<00000000000c70c0>] (suspected corrupt symbol)