I am facing a low memory available problem in arduino. I am compiling a big sketch for arduino mega 2560.

Analysing a .elf file, the avr-size tool gives:

text    data     bss     dec     hex filename
68524   4392    2560   75476   126d4 C:\Users\LEAN...

And the avr-nm (avr-nm doc) shows only variables with t, T, b, d and B. The following is how the command is executed (the output is being saved in a file called test.txt).

   avr-nm -a -td -C -l --size-sort -r x.elf >> test.txt

Then, I perform a sum to confirm the avr-size result using this Python script:

f = open("test.txt", "r")
lines = f.readlines()
f.close()

su = 0
dsum = 0
bsum = 0
tsum = 0
gsum = 0
for line in lines:
    #print(line, end="")
    s = line.split()
    try:
        val = int(s[0])
        su = su + val
        if(s[1].lower() == 'b'):
            bsum = bsum + val
        if(s[1].lower() == 'd'):
            print(line)
            dsum = dsum + val
        if(s[1].lower() == 't'):
            tsum = tsum + val
        if(s[1].lower() == 'g'):
            gsum = gsum + val
    except:
        print("ERR: ",s[0])
print("\n\nSIZE: ", su)
print("SIZE d/D: ", dsum)
print("SIZE b/B: ", bsum)
print("SIZE t/T: ", tsum)
print("SIZE g/G: ", gsum)

and the sum result of each var type is:

SIZE:  71015
SIZE d/D:  135
SIZE b/B:  2560
SIZE t/T:  68320
SIZE g/G:  0

The question: Here d/D sums is 135 bytes. So, why the data segment reported by avr-size is 4392 bytes? how to find out what is occupying this space?

Best Regards.

EDIT

It must be a Joke!

I have a lot of like this in the code:

Serial.print("QTDE REG: ");

Just changing for this:

Serial.print(F("QTDE REG: "));

I have reduced by 10 the .data size!

So, in this way Serial.print("QTDE REG: "); "QTDE REG: " is stored as a global variable?? I thought the compiler would save locally.

EDIT 2

I have an advance running avr-objdump -s -j .data x.elf as suggested by Edgar below. Now I see that all my string literals are in data! For example:

void myFunction(){
    ...
    sprintf(buf, "{\"name\":\"Intervalo de Registros\",\"value\":\"%d\", \"unit\":\"C\"},", (int)settings.treg);
    ...
}

avr-objdump -s -j .data x.elf shows:

 800660 2c007b22 6e616d65 223a2249 6e746572  ,.{"name":"Inter
 800670 76616c6f 20646520 52656769 7374726f  valo de Registro
 800680 73222c22 76616c75 65223a22 2564222c  s","value":"%d",
 800690 2022756e 6974223a 2243227d 2c007b22   "unit":"C"},.{"