Is there a clear, simple explanation of how to setup the gcc linker scripts?

[Mron]

I've been trying to run some of the examples provided with the SDK's. Blinky is the only one I've gotten to work for sure. I think I haven't set up the linker scripts properly.

I've been looking at a couple linker scripts for nrf51822's. The number of sections change, the values to allocate rom and ram change. Is there a clear tutorial or document that explains the use and proper structure of these files? I understand the amount of rom and ram vary depending on the device and model. I need to understand how to properly allocate these resources.

What effects these allocations? For instance, does adding a library require a change the linker script?

[Mron]

I've run down info on linker script syntax and function. I would like to know when and how to modify them.

[Turbo J]

There are a lot of them in the SDK examples, and they should work for most custom projects without any modifications.

[Mron]

Thanks for your reply. i have found many .ld scripts to look at., Very few are well documented. I've had trouble getting examples to run, and several times it's because I picked the wrong .ld. Having one or two well documented examples would help me understand what i'm looking at when I open a .ld file. For instance few use .ld math. For instance:

FLASH (rx) : ORIGIN = 0x1b000, LENGTH = 0x40000 - 0x1b000 <- clearer to me
vs

FLASH (rx) : ORIGIN = 0x1b000, LENGTH = 0x25000 <- where did this number come from?

and .ld files for the same board and same soft device will have different values:

RAM (rwx) :  ORIGIN = 0x20002bd8, LENGTH = 0x5428 <- sometimes it's this

RAM (rwx) :  ORIGIN = 0x20001eb0, LENGTH = 0x6150 <- and sometimes this --- Why did this one need less RAM for the soft device ?

[Turbo J]

Elementary Math: 0x40000 - 0x1b000 = 0x25000

Softdevice RAM usage depends on how many features you enable. See documentation for sd_ble_enable() function call.

[Mron]

"ORIGIN = 0x1b000, LENGTH = 0x40000 - 0x1b000"  is more understandable. As my elementary school teacher would say- "Show your work".

This is the info I needed: "Softdevice RAM usage depends on how many features you enable. See documentation for sd_ble_enable() function call."

Thanks