Difference between physical/logical/virtual memory address

Question

I am a little confused about the terms physical/logical/virtual addresses in an Operating System(I use Linux- open SUSE)

Here is what I understand:

Answer 1

when u write a small program eg:

int a=10;
int main()
{
 printf("%d",a);
}   


compile: >gcc -c fname.c
>ls 
fname.o //fname.o is generated
>readelf -a fname.o >readelf_obj.txt

/readelf is a command to understand the object files and executabe file which will be in 0s and 1s. output is written in readelf_onj.txt file/

`>vim readelf_obj.txt`

/* under "section header" you will see .data .text .rodata sections of your object file. every starting or the base address is started from 0000 and grows to the respective size till it reach the size under the heading "size"----> these are the logical addresses.*/

>gcc fname.c
>ls
a.out //your executabe
>readelf -a a.out>readelf_exe.txt
>vim readelf_exe.txt 

/* here the base address of all the sections are not zero. it will start from particular address and end up to the particular address. The linker will give the continuous adresses to all the sections (observe in the readelf_exe.txt file. observe base address and size of each section. They start continuously) so only the base addresses are different.---> this is called the virtual address space.*/

Physical address-> the memory ll have the physical address. when your executable file is loaded into memory it ll have physical address. Actually the virtual adresses are mapped to physical addresses for the execution.