What is the section for uninitialized global data? - gcc

Question

I am a little confused as to where uninitialized global variables go in the ELF file. I have this simple program to test in which sections the variables will be located:
const int a = 11;
int b = 10;
int c;
int main()
{
return 0;
}
I know that uninitialized global variable should be put into .bss section of ELF file, but objdump -h gives me the following output:
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 0000000a 00000000 00000000 00000034 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .data 00000004 00000000 00000000 00000040 2**2
CONTENTS, ALLOC, LOAD, DATA
2 .bss 00000000 00000000 00000000 00000044 2**2
ALLOC
3 .rodata 00000004 00000000 00000000 00000044 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
4 .comment 00000024 00000000 00000000 00000048 2**0
CONTENTS, READONLY
5 .note.GNU-stack 00000000 00000000 00000000 0000006c 2**0
CONTENTS, READONLY
So the variable a goes to .rodata, b goes to .data, and c goes nowhere? When i change the code to:
int c = 0;
everything is as expected - .bss section has the length 4, but what happens with the variable c when it is not initialized?

Answer 1

It goes into a "common section". You can see it with objdump -t or by using nm.
I'm not quite sure I understand what this is about, but the reference to the ld -warn-common flag says this:
int i;
A common symbol. If there are only
(one or more) common symbols for a
variable, it goes in the uninitialized
data area of the output file. The
linker merges multiple common symbols
for the same variable into a single
symbol. If they are of different
sizes, it picks the largest size. The
linker turns a common symbol into a
declaration, if there is a definition
of the same variable.
(Found via the nm man page.) There is more information after that in the man page itself.