How to use custom linker script with mbed-cli?

[drahnr]

Description

mbed-os 5.9.1-rc1
mbed-cli 1.7.2

Trying to use a custom linker file always fails:
Just placing it under my custom target dir still yields the issue as described in ARMmbed/mbed-cli#687 and #6914

Also trying to explicitly set the linker file via the cmd line opt -l fails the same way:

mbed compile --target MY_TARGET --app-config ./config/mbed_app.json --profile ./config/debug.json -N artifact -DLAUNCH_APP=18 -l ./src/TARGET_MY_TARGET/MY_TARGET.ld

The underlying question is more, on how to properly use a custom linker file by means of defineing a custom target and exploiting the implicit directory structure, such that the derived MCU linker file does not collide with the custom linker script?

Issue request type

[x] Question
[ ] Enhancement
[x] Bug

[ciarmcom]

ARM Internal Ref: MBOTRIAGE-422

[0xc0170]

This should be fixed soon (those misleading error msg). I tested building mbed 2 on 5.9 rc2 candidate.

#7124 - this PR should fix it (one more commit to be added there).

[drahnr]

But this does not really fix the usecase of a custom linker file? Does it?

[theotherjimmy]

@drahnr it does fix the error, the custom linker scirpt thing is supposed to work, aside from that bug.

[drahnr]

@theotherjimmy thanks for clarifying, tracking that PR, thanks!

[theotherjimmy]

@drahnr, @0xc0170 is mistaken, the PR he mentioned, #7124, has nothing to do with linker scripts. The PR that fixed it is #6914

[0xc0170]

Closing as resolved, please reopen if there is still a problem

[mattbrown015]

@theotherjimmy sorry to start going over old ground but the comments above confused me a bit...

Just to be clear, placing a linker script in custom target folder is the correct thing to(?).

I created TARGET_MYTARGET\my-script.ld and it appeared to be found and used.

The warning I get is by design and the issues discussed above are because, for a while, an error occurred.

Warning: Multiple linker scripts detected: .\mbed-os\targets\TARGET_STM\TARGET_STM32L4\TARGET_STM32L432xC\device\TOOLCHAIN_GCC_ARM\STM32L432XX.ld -> .\TARGET_MYTARGET\my-script.ld

Mbed CLI 1.7.5
Mbed OS f4382d9

[theotherjimmy]

@mattbrown015 Yes, the warning is by design, as we can probably arbitrarily pick a linker script. There may have been an error in the past, yes.

[mattbrown015]

as we can probably arbitrarily pick a linker script

@theotherjimmy words like 'arbitrary' are a bit of a problem in the context of a build system :-}

Are you suggesting it may use the custom target linker script or it may use the base target linker script, depending on which one it found first?

If this is the case it sounds like a problem to me. Hopefully you don't mean this and it knows the custom target is more important but the warning is for other situations.

[drahnr]

Event the warning is a bit of a red hering and not clear which linker script is used at first glance.

Maybe printing all found linker scripts and then marking the one that is used would be clearer.