STM32 storage allocation problem

After keil compilation, the following information is generated:
Program Size: Code=37970 RO-data=7598 RW-data=212 ZI-data=12340  What do code ro-data rw-data zi-data mean respectively
?

Answer:
Code segment + initialized data segment = FLASH, data segment + 0 initialized data segment = RAM; 


RO, RW and ZI DATA segments in ARM compilation
ARM program (referring to the program being executed in the ARM system, not the bin file saved in ROM) composition
An ARM program contains 3 parts: RO segment, RW segment and ZI segment
RO is the instruction and constant in the program
RW is the initialized variable in the program
ZI is the uninitialized variable in the program
The above 3 points can be understood as:
RO is readonly,
RW is read/write,
ZI is zero
Composition of ARM image file
The so-called ARM image file refers to the bin file burned into ROM, also known as image file. It is called Image file below.
Image file contains RO and RW data.
The reason why Image file does not contain ZI data is that ZI data is all 0, so it is not necessary to include it. Just clear the area where ZI data is before running the program. Including it will waste storage space.

Q: Why must RO and RW be included in the Image?
A: Because the instructions and constants in RO and the variables initialized in RW cannot be created out of nothing like ZI. From the above two points, we can know that
the execution process of the ARM program
is not exactly the same as the image file burned into the ROM and the ARM program in actual operation. Therefore, it is necessary to understand how the ARM program reaches the actual running state from the image in the ROM.
In fact, the instructions in RO should at least have the following functions:
1. Move RW from ROM to RAM, because RW is a variable and variables cannot exist in ROM.
2. Clear all RAM areas where ZI is located, because the ZI area is not in the Image, so the program needs to clear the corresponding RAM area according to the ZI address and size given by the compiler. ZI is also a variable. Similarly: variables cannot exist in ROM. In the
initial stage of program operation, the C program can access variables normally only after the instructions in RO complete these two tasks. Otherwise, only code without variables can be run.
After all the above, you may still be confused. What are RO, RW and ZI? Below I will give a few examples to explain what RO, RW and ZI mean in C. 
1; RO
Look at the following two programs. There is a statement between them, which is to declare a character constant. Therefore, according to what we said before, there should only be one byte difference in RO data (character constant is 1 byte).
Prog1:
#include 
void main(void)
{
;
}
Prog2:
#include 

const char a = 5；
void main(void)
{
;
}
The compiled information of Prog1 is as follows:
======================================================================================
Code RO Data RW Data ZI Data Debug
948 60 0 96 0 Grand Totals
=======================================================================================================
Total RO Size(Code + RO Data) 1008 ( 0.98kB)
Total RW Size(RW Data + ZI Data) 96 ( 0.09kB)
Total ROM Size(Code + RO Data + RW Data) 1008 ( 0.98kB)
==========================================================================================
The information after Prog2 compiles is as follows:
===================================================================================================
Code RO Data RW Data ZI Data Debug
948 61 0 96 0 Grand Totals
==================================================================================
Total RO Size(Code + RO Data) 1009 (0.99kB)
Total RW Size(RW Data + ZI Data) 96 (0.09kB)

Total ROM Size(Code + RO Data + RW Data) 1009 ( 0.99kB )
=== ... Prog3: #include  void main(void) { ; } Prog4: #include  char a = 5; void main(void) { ; }

The information after Prog3 compiles is as follows:
=================================================================================
Code RO Data RW Data ZI Data Debug
948 60 0 96 0 Grand Totals
=======================================================================================================
Total RO Size(Code + RO Data) 1008 ( 0.98kB)
Total RW Size(RW Data + ZI Data) 96 ( 0.09kB)
Total ROM Size(Code + RO Data + RW Data) 1008 ( 0.98kB)
==============================================================================================
The information compiled by Prog4 is as follows:
========================================================================================================
Code RO Data RW Data ZI Data Debug
948 60 1 96 0 Grand Totals
================================================================================
Total RO Size(Code + RO Data) 1008 (0.98kB)
Total RW Size(RW Data + ZI Data) 97 (0.09kB)
Total ROM Size(Code + RO Data + RW Data) 1009 (0.99kB)
===
...

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​
​
​ 
​

}
;
}
Prog4:
#include 
char a；
void main(void)
}
;
}
The compiled information of Prog3 is as follows:
=========================================================================================
Code RO Data RW Data ZI Data Debug
948 60 0 96 0 Grand Totals
==============================================================================================================
Total RO Size(Code + RO Data) 1008 ( 0.98kB)
Total RW Size(RW Data + ZI Data) 96 ( 0.09kB)
Total ROM Size(Code + RO Data + RW Data) 1008 ( 0.98kB)
===========================================================================================
The information compiled by Prog4 is as follows:
=====================================================================================================
Code RO Data RW Data ZI Data Debug
948 60 0 97 0 Grand Totals
==========================================================================
Total RO Size(Code + RO Data) 1008 ( 0.98kB)
Total RW Size(RW Data + ZI Data) 97 ( 0.09kB)
Total ROM Size(Code + RO Data + RW Data ) 1008 ( 0.98kB)
===
...
​
​
​
​
​
​
Appendix:
Program compilation command (assuming the C program is named tst.c):
armcc -c -o tst.o tst.c
armlink -noremove -elf -nodebug -info totals -info sizes -map -list aa.map -o tst.elf
The compiled information of tst.o is in the aa.map file.
ROM mainly refers to: NAND Flash, Nor Flash
RAM mainly refers to: PSRAM, SDRAM, SRAM, DDRAM