Increase background stack size to fix overflows

[c1728p9]

Description

On platforms using both tickless and the low power ticker wrapper so much of the background stack is used that it overflows. To ensure the background thread's stack doesn't overflow in any configuration increase this size by 256 bytes. Worst case usage on the NUCLEO_F476RG was recorded at 656 when tickless is turned on so this increased size should safely prevent overflows.

Pull request type

[x] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Docs update
[ ] Test update
[ ] Breaking change

[c1728p9]

This is one possible fix for #8184

[jeromecoutant]

There is no condition on TICKLESS ?

[c1728p9]

Right now this patch bumps the background stack size regardless of if tickless is on. If this is too much overhead I could make two configs - one for with tickless and one for without.

[deepikabhavnani]

Right now this patch bumps the background stack size regardless of if tickless is on. If this is too much overhead I could make two configs - one for with tickless and one for without.

We have few devices with limited RAM, I am 90% sure we will see failures in CI for those specific targets, but in few test we skip if enough memory is not available. Good to have it configurable

[c1728p9]

I updated this PR to only increase the background stack size when tickless is enabled.

[0xc0170]

/morph build

[mbed-ci]

Build : FAILURE

Build number : 3554
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/8551/

[0xc0170]

Please review the build failures. Few small targets fail for IAR (placement errors)

[c1728p9]

I updated this PR so the background thread stack is only increased if both MBED_TICKLESS and LPTICKER_DELAY_TICKS are used. This should allow the small devices without enough ram to build as these are not using LPTICKER_DELAY_TICKS.

[cmonr]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 3565
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/8551/

Triggering tests

/morph test
/morph export-build
/morph mbed2-build

[mbed-ci]

Exporter Build : FAILURE

Build number : 3172
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/8551/

[0xc0170]

/morph export-build

[mbed-ci]

Test : SUCCESS

Build number : 3345
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/8551/3345

[mbed-ci]

Exporter Build : FAILURE

Build number : 3178
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/8551/

[cmonr]

Note: This PR is now a part of a rollup PR (#8675).

Jenkins CI export nodes experienced many drops throughout the day causing false failures. In an attempt to get those PRs through CI, while keeping CI load low, several PRs have been bundled into a single rollup PR.

If any more commits are made in this PR, this PR will remain open and have to go through CI on its own.