Where does main function get allocated?
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When concerned with a memory layout for a process, all function calls within the process get a new stack-frame into the stack.
I'm not sure if this is true for main function as it seems like main does more things than serving as an entry-point function.
Does main function also gets its own stack-frame upon initialization of the a new process?
If this is implementation specific details, explanation for a typical Linux implementation would be useful.
process c
edited Mar 17 at 14:27
ctrl-alt-delor
12.5k52662
asked Mar 16 at 13:59
gnisgnis
136
|
show 5 more comments
When concerned with a memory layout for a process, all function calls within the process get a new stack-frame into the stack.
I'm not sure if this is true for main function as it seems like main does more things than serving as an entry-point function.
Does main function also gets its own stack-frame upon initialization of the a new process?
If this is implementation specific details, explanation for a typical Linux implementation would be useful.
process c
edited Mar 17 at 14:27
ctrl-alt-delor
12.5k52662
asked Mar 16 at 13:59
gnisgnis
136
1
Usually_startis the entry point rather thanmain- seehttps://stackoverflow.com/questions/29694564/what-is-the-use-of-start-in-c
– Torin
Mar 16 at 14:16
1
Subroutines share a stack (They have to): If they had different stack, then which stack would we activated when a subroutine returns? Andmainis just another subroutine, it is call by_start.
– ctrl-alt-delor
Mar 16 at 14:35
This is a general C/C++ language programming question rather than a Unix & Linux one, as it applies to, and could be asked in this very form about, C/C++ language programming on a lot of platforms.
– JdeBP
Mar 16 at 17:37
@ctrl-alt-delor Ifmainis just another subroutine, can I also say that it follows the same step withnon-mainfunctions when it comes to memory stack allocation?
– gnis
Mar 17 at 14:16
@JdeBP I thought it waskernelthat bootstraps things including memory layout upon process initialization, so UNIX & Linux was more adequate forum to ask about. C language itself doesn't have any authority over where and how it(the program itself) gets allocated/managed.
– gnis
Mar 17 at 14:18
|
show 5 more comments
When concerned with a memory layout for a process, all function calls within the process get a new stack-frame into the stack.
I'm not sure if this is true for main function as it seems like main does more things than serving as an entry-point function.
Does main function also gets its own stack-frame upon initialization of the a new process?
If this is implementation specific details, explanation for a typical Linux implementation would be useful.
process c
edited Mar 17 at 14:27
ctrl-alt-delor
12.5k52662
asked Mar 16 at 13:59
gnisgnis
136
When concerned with a memory layout for a process, all function calls within the process get a new stack-frame into the stack.
I'm not sure if this is true for main function as it seems like main does more things than serving as an entry-point function.
Does main function also gets its own stack-frame upon initialization of the a new process?
If this is implementation specific details, explanation for a typical Linux implementation would be useful.
process c
process c
edited Mar 17 at 14:27
ctrl-alt-delor
12.5k52662
asked Mar 16 at 13:59
gnisgnis
136
edited Mar 17 at 14:27
ctrl-alt-delor
12.5k52662
asked Mar 16 at 13:59
gnisgnis
136
edited Mar 17 at 14:27
ctrl-alt-delor
12.5k52662
edited Mar 17 at 14:27
ctrl-alt-delor
12.5k52662
edited Mar 17 at 14:27
ctrl-alt-delor
12.5k52662
12.5k52662
asked Mar 16 at 13:59
gnisgnis
136
asked Mar 16 at 13:59
gnisgnis
136
asked Mar 16 at 13:59
gnisgnis
136
136
1
Usually_startis the entry point rather thanmain- seehttps://stackoverflow.com/questions/29694564/what-is-the-use-of-start-in-c
– Torin
Mar 16 at 14:16
1
Subroutines share a stack (They have to): If they had different stack, then which stack would we activated when a subroutine returns? Andmainis just another subroutine, it is call by_start.
– ctrl-alt-delor
Mar 16 at 14:35
This is a general C/C++ language programming question rather than a Unix & Linux one, as it applies to, and could be asked in this very form about, C/C++ language programming on a lot of platforms.
– JdeBP
Mar 16 at 17:37
@ctrl-alt-delor Ifmainis just another subroutine, can I also say that it follows the same step withnon-mainfunctions when it comes to memory stack allocation?
– gnis
Mar 17 at 14:16
@JdeBP I thought it waskernelthat bootstraps things including memory layout upon process initialization, so UNIX & Linux was more adequate forum to ask about. C language itself doesn't have any authority over where and how it(the program itself) gets allocated/managed.
– gnis
Mar 17 at 14:18
|
show 5 more comments
1
Usually_startis the entry point rather thanmain- seehttps://stackoverflow.com/questions/29694564/what-is-the-use-of-start-in-c
– Torin
Mar 16 at 14:16
1
Subroutines share a stack (They have to): If they had different stack, then which stack would we activated when a subroutine returns? Andmainis just another subroutine, it is call by_start.
– ctrl-alt-delor
Mar 16 at 14:35
This is a general C/C++ language programming question rather than a Unix & Linux one, as it applies to, and could be asked in this very form about, C/C++ language programming on a lot of platforms.
– JdeBP
Mar 16 at 17:37
@ctrl-alt-delor Ifmainis just another subroutine, can I also say that it follows the same step withnon-mainfunctions when it comes to memory stack allocation?
– gnis
Mar 17 at 14:16
@JdeBP I thought it waskernelthat bootstraps things including memory layout upon process initialization, so UNIX & Linux was more adequate forum to ask about. C language itself doesn't have any authority over where and how it(the program itself) gets allocated/managed.
– gnis
Mar 17 at 14:18
1
1
Usually
_start is the entry point rather than main - seehttps://stackoverflow.com/questions/29694564/what-is-the-use-of-start-in-c– Torin
Mar 16 at 14:16
Usually
_start is the entry point rather than main - seehttps://stackoverflow.com/questions/29694564/what-is-the-use-of-start-in-c– Torin
Mar 16 at 14:16
1
1
Subroutines share a stack (They have to): If they had different stack, then which stack would we activated when a subroutine returns? And
main is just another subroutine, it is call by _start.– ctrl-alt-delor
Mar 16 at 14:35
Subroutines share a stack (They have to): If they had different stack, then which stack would we activated when a subroutine returns? And
main is just another subroutine, it is call by _start.– ctrl-alt-delor
Mar 16 at 14:35
This is a general C/C++ language programming question rather than a Unix & Linux one, as it applies to, and could be asked in this very form about, C/C++ language programming on a lot of platforms.
– JdeBP
Mar 16 at 17:37
This is a general C/C++ language programming question rather than a Unix & Linux one, as it applies to, and could be asked in this very form about, C/C++ language programming on a lot of platforms.
– JdeBP
Mar 16 at 17:37
@ctrl-alt-delor If
main is just another subroutine, can I also say that it follows the same step with non-main functions when it comes to memory stack allocation?– gnis
Mar 17 at 14:16
@ctrl-alt-delor If
main is just another subroutine, can I also say that it follows the same step with non-main functions when it comes to memory stack allocation?– gnis
Mar 17 at 14:16
@JdeBP I thought it was
kernel that bootstraps things including memory layout upon process initialization, so UNIX & Linux was more adequate forum to ask about. C language itself doesn't have any authority over where and how it(the program itself) gets allocated/managed.– gnis
Mar 17 at 14:18
@JdeBP I thought it was
kernel that bootstraps things including memory layout upon process initialization, so UNIX & Linux was more adequate forum to ask about. C language itself doesn't have any authority over where and how it(the program itself) gets allocated/managed.– gnis
Mar 17 at 14:18
|
show 5 more comments
1 Answer
1
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oldest
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Usually _start is the entry point rather than main.
main is just another subroutine, it is call by _start. It gets a stack-frame, on the stack, just like any other subroutine.
However the kernel does not do as much as you may think. There is code in the process run before main (it _start it is generated by the C compiler, but not part of the C program), that does a lot. There is even code run before exec (before the C program runs), such as setting up stdin, stdout and stderr.
The kernel may do some tricks with _start, it can not be run like other subroutines, but it will look like it is: The kernel will set up the process as if _entry had just been called (but it was not). If control passes back to _start then exit is called.
(I may have glossed over some detail, including _entry).
answered Mar 17 at 14:40
ctrl-alt-delorctrl-alt-delor
12.5k52662
add a comment |
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Usually _start is the entry point rather than main.
main is just another subroutine, it is call by _start. It gets a stack-frame, on the stack, just like any other subroutine.
However the kernel does not do as much as you may think. There is code in the process run before main (it _start it is generated by the C compiler, but not part of the C program), that does a lot. There is even code run before exec (before the C program runs), such as setting up stdin, stdout and stderr.
The kernel may do some tricks with _start, it can not be run like other subroutines, but it will look like it is: The kernel will set up the process as if _entry had just been called (but it was not). If control passes back to _start then exit is called.
(I may have glossed over some detail, including _entry).
answered Mar 17 at 14:40
ctrl-alt-delorctrl-alt-delor
12.5k52662
add a comment |
Usually _start is the entry point rather than main.
main is just another subroutine, it is call by _start. It gets a stack-frame, on the stack, just like any other subroutine.
However the kernel does not do as much as you may think. There is code in the process run before main (it _start it is generated by the C compiler, but not part of the C program), that does a lot. There is even code run before exec (before the C program runs), such as setting up stdin, stdout and stderr.
The kernel may do some tricks with _start, it can not be run like other subroutines, but it will look like it is: The kernel will set up the process as if _entry had just been called (but it was not). If control passes back to _start then exit is called.
(I may have glossed over some detail, including _entry).
answered Mar 17 at 14:40
ctrl-alt-delorctrl-alt-delor
12.5k52662
add a comment |
Usually _start is the entry point rather than main.
main is just another subroutine, it is call by _start. It gets a stack-frame, on the stack, just like any other subroutine.
However the kernel does not do as much as you may think. There is code in the process run before main (it _start it is generated by the C compiler, but not part of the C program), that does a lot. There is even code run before exec (before the C program runs), such as setting up stdin, stdout and stderr.
The kernel may do some tricks with _start, it can not be run like other subroutines, but it will look like it is: The kernel will set up the process as if _entry had just been called (but it was not). If control passes back to _start then exit is called.
(I may have glossed over some detail, including _entry).
answered Mar 17 at 14:40
ctrl-alt-delorctrl-alt-delor
12.5k52662
Usually _start is the entry point rather than main.
main is just another subroutine, it is call by _start. It gets a stack-frame, on the stack, just like any other subroutine.
However the kernel does not do as much as you may think. There is code in the process run before main (it _start it is generated by the C compiler, but not part of the C program), that does a lot. There is even code run before exec (before the C program runs), such as setting up stdin, stdout and stderr.
The kernel may do some tricks with _start, it can not be run like other subroutines, but it will look like it is: The kernel will set up the process as if _entry had just been called (but it was not). If control passes back to _start then exit is called.
(I may have glossed over some detail, including _entry).
answered Mar 17 at 14:40
ctrl-alt-delorctrl-alt-delor
12.5k52662
answered Mar 17 at 14:40
ctrl-alt-delorctrl-alt-delor
12.5k52662
answered Mar 17 at 14:40
ctrl-alt-delorctrl-alt-delor
12.5k52662
answered Mar 17 at 14:40
ctrl-alt-delorctrl-alt-delor
12.5k52662
12.5k52662
add a comment |
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Usually
_startis the entry point rather thanmain- seehttps://stackoverflow.com/questions/29694564/what-is-the-use-of-start-in-c– Torin
Mar 16 at 14:16
1
Subroutines share a stack (They have to): If they had different stack, then which stack would we activated when a subroutine returns? And
mainis just another subroutine, it is call by_start.– ctrl-alt-delor
Mar 16 at 14:35
This is a general C/C++ language programming question rather than a Unix & Linux one, as it applies to, and could be asked in this very form about, C/C++ language programming on a lot of platforms.
– JdeBP
Mar 16 at 17:37
@ctrl-alt-delor If
mainis just another subroutine, can I also say that it follows the same step withnon-mainfunctions when it comes to memory stack allocation?– gnis
Mar 17 at 14:16
@JdeBP I thought it was
kernelthat bootstraps things including memory layout upon process initialization, so UNIX & Linux was more adequate forum to ask about. C language itself doesn't have any authority over where and how it(the program itself) gets allocated/managed.– gnis
Mar 17 at 14:18