Revert "kernel: Enable interrupts for MULTITHREADING=n on supported arch's"

This reverts commit 17e9d623b4.

Single thread keep introducing more issues, decided to remove the
feature completely and push any required changes for after 1.13.

See #9808

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

include/arch/arm/cortex_m/asm_inline_gcc.h

@@ -175,8 +175,6 @@ static ALWAYS_INLINE void _arch_irq_unlock(unsigned int key)
 #endif /* CONFIG_ARMV6_M_ARMV8_M_BASELINE */
 }
 
-/* Used to unconditionally enable interrupts when MULTITHREADING=n */
-#define Z_ARCH_INT_ENABLE() _arch_irq_unlock(0)
 
 #endif /* _ASMLANGUAGE */
 

include/arch/x86/arch.h

@@ -445,9 +445,6 @@ static ALWAYS_INLINE void _arch_irq_unlock(unsigned int key)
 	_do_irq_unlock();
 }
 
-/* Used to unconditionally enable interrupts when MULTITHREADING=n */
-#define Z_ARCH_INT_ENABLE() _arch_irq_unlock(0x200)
-
 /**
  * The NANO_SOFT_IRQ macro must be used as the value for the @a irq parameter
  * to NANO_CPU_INT_REGISTER when connecting to an interrupt that does not

kernel/init.c

@@ -436,18 +436,6 @@ sys_rand32_fallback:
 extern uintptr_t __stack_chk_guard;
 #endif /* CONFIG_STACK_CANARIES */
 
-#ifndef CONFIG_MULTITHREADING
-static void enable_interrupts(void)
-{
-#ifdef Z_ARCH_INT_ENABLE
-	Z_ARCH_INT_ENABLE();
-#else
-# pragma message "Z_ARCH_INT_ENABLE not defined for this architecture."
-# pragma message "Entry to MULTITHREADING=n app code will be with interrupts disabled."
-#endif
-}
-#endif
-
 /**
  *
  * @brief Initialize kernel
@@ -502,7 +490,6 @@ FUNC_NORETURN void _Cstart(void)
 	prepare_multithreading(dummy_thread);
 	switch_to_main_thread();
 #else
-	enable_interrupts();
 	bg_thread_main(NULL, NULL, NULL);
 
 	irq_lock();