Unclear in what mode I work and how to use uint64_t

[mrjbom]

I'm using GRUB to boot and expect it to boot me into protected mode, but it looks like it's booting me into long mode.

I ran my operating system on a virtual machine with 5120 megabytes of RAM and got this output:

THIS INT32 OUTPUT SECTION
ram_available = 1073282048 bytes
ram_available = 1023 MB
THIS UINT32 OUTPUT SECTION
ram_available = 1073282048 bytes
ram_available = 1023 MB

It is obvious that I get such numbers because of variable overflow, but I expected to see 4 GB because in protected mode it is no longer available. In the end, you can see that all 5 GB are indexed but they are not impossible to remove.
I tried using uint64_t to implement the char* itoaUINT64(uint64_t value, char* result, int base); function, but got a compilation error: Undefined reference to '__divdi3'.

-static-libgcc -lgcc not help.

Source code here
gcc args here in string №73
itoaUINT64() here

How do I solve this problem?

[Octocontrabass]

It is obvious that I get such numbers because of variable overflow, but I expected to see 4 GB because in protected mode it is no longer available.

If you use PAE, you can access all memory even in protected mode.

I tried using uint64_t but got a compilation error: Undefined reference to '__divdi3'.

All code compiled with GCC must be linked with libgcc. You can do that by changing line 94 to use GCC instead of LD for linking, and adding "-lgcc" to the command line after your object files. (You may also need to add ./i386-elf-4.9.1-Linux-x86_64/bin/ to your $PATH.)

[iocoder]

-static-libgcc -lgcc not help.

Because in your build_all_crosscompile.sh, you added '-lgcc' to your compiler command line, not the linker...

[mrjbom]

It is obvious that I get such numbers because of variable overflow, but I expected to see 4 GB because in protected mode it is no longer available.

If you use PAE, you can access all memory even in protected mode.

I tried using uint64_t but got a compilation error: Undefined reference to '__divdi3'.

All code compiled with GCC must be linked with libgcc. You can do that by changing line 94 to use GCC instead of LD for linking, and adding "-lgcc" to the command line after your object files. (You may also need to add ./i386-elf-4.9.1-Linux-x86_64/bin/ to your $PATH.)

Thanks.