samples: smp_svr: enable support for both small and big heaps

[butok]

• Fix non-functional smp_svr for platforms with RAM < 256KB. By default they have support for small heaps only (CONFIG_SYS_HEAP_SMALL_ONLY).
• Use CONFIG_SYS_HEAP_AUTO=y for the project. It enables support for both small and big heaps.
• Proven on a platform with 128KB RAM.

[nordicjm]

What here is needing heap? Heap is disabled by default when you configure this and I've ran this many times on devices with less than 256KiB of RAM without issue

[butok]

Hi @nordicjm

What here is needing heap? Heap is disabled by default when you configure

Right, even if KERNEL_MEM_POOL is enabled, the heap size is zero.

and I've ran this many times on devices with less than 256KiB of RAM without issue

Switching from SYS_HEAP_SMALL_ONLY to CONFIG_SYS_HEAP_AUTO has helped for frdm-mcxa156.
I will try to find other boards with 128KB of RAM,
and to investigate if this is a common issue or a problem specific to mcxa156.

It's not critical. If you want, I can close the PR for further investigation.

[nordicjm]

What transport/commands are you running or where is the error shown/in response to what? Will try it on a board here

[butok]

Closing, after further testing, a problem was on my side.