Malloc returns NULL

1) Stop making any calls to _init_alloc.

2) You should be getting a link error on TEST2, no compile error. See #4 below. This would only seem to be if you exported __heap_limit, __heap_base and __initial_sp. If you export these, it will compile and link fine using both microlib and standardlib, but will not actually work in standardlib mode. Did you somehow change the standard code in a way that these variables were exported when not using the microlib? You may notice in the map file that sys_stackheap_outer.o references a __user_inital_stackheap that resides in sys_stackheap_outer.o when these are exported. If you do not export these variables, it will reference the __user_initial_stackheap in YOUR startup.s file. This is why your __user_initial_stackheap is not being called. i.e. You are not using the "standard" code at all, you have modified it to not work and then complained about it not working.

3) Look at your map file

USING:__user_setup_stackheap,

your map file should show __rtentry4.o referencing __user_setup_stackheap in your startup.s file.  There is no reference to __user_initial_stackheap.

USING: __user_initial_stackheap

your mapfile should show sys_stackheap_outer.o referenceing __user_initial_stackheap in your startup.s file.  You will also see __user_setup_stackheap referenceing sys_stackheap_outer.o

4) I have never seen __heap_limit defined as a variable when not using the microlib. I think the "standard" startup code is very specific in NOT creating a __heap_limit or __heap_base variable when not using the microlib. Don't define this as a variable.

1) Stop making any calls to _init_alloc.

2) You should be getting a link error on TEST2, no compile error. See #4 below. This would only seem to be if you exported __heap_limit, __heap_base and __initial_sp. If you export these, it will compile and link fine using both microlib and standardlib, but will not actually work in standardlib mode. Did you somehow change the standard code in a way that these variables were exported when not using the microlib? You may notice in the map file that sys_stackheap_outer.o references a __user_inital_stackheap that resides in sys_stackheap_outer.o when these are exported. If you do not export these variables, it will reference the __user_initial_stackheap in YOUR startup.s file. This is why your __user_initial_stackheap is not being called. i.e. You are not using the "standard" code at all, you have modified it to not work and then complained about it not working.

3) Look at your map file

USING:__user_setup_stackheap,

your map file should show __rtentry4.o referencing __user_setup_stackheap in your startup.s file.  There is no reference to __user_initial_stackheap.

USING: __user_initial_stackheap

your mapfile should show sys_stackheap_outer.o referenceing __user_initial_stackheap in your startup.s file.  You will also see __user_setup_stackheap referenceing sys_stackheap_outer.o

4) I have never seen __heap_limit defined as a variable when not using the microlib. I think the "standard" startup code is very specific in NOT creating a __heap_limit or __heap_base variable when not using the microlib. Don't define this as a variable.

It works now as expected, it was all related to one of all of the added lines at the top of startup_LPC..

                EXPORT  __initial_sp
                EXPORT  __heap_base
                EXPORT  __heap_limit

If any of them, even if the program only have "EXPORT __initial_sp" (and not the other two) the heap dont get initalized. If none of them are exported then the runtime library will call __user_initial_stackheap as expected.

It is neccessary to export a new/seperate variabel if the stack top is going to be used
somewhere else, like this

                EXPORT  __initial_stack_top


Stack_Size      EQU     0x00000800

                AREA    STACK, NOINIT, READWRITE, ALIGN=3
Stack_Mem       SPACE   Stack_Size
__initial_sp
__initial_stack_top

One interesting observation was that if the program had

                EXPORT  __initial_sp
                EXPORT  __heap_base
                EXPORT  __heap_limit

The map file will contain
__rtentry4.o(.ARM.Collect$$rtentry$$00000004) refers to sys_stackheap_outer.o(.text) for __user_setup_stackheap
sys_stackheap_outer.o(.text) refers to startup_lpc17xx.o(.text) for __user_initial_stackheap

But they was never called

Conclusive:
Dont export any of __initial_sp, __heap_base or __heap_limit form the startup_XXXX.s