Best way of implementing heap allocation in user space?

[ChocolateLoverRaj]

This is how I currently manage user space memory:

• 0x0-size of elf: The ELF
• size of elf-size of elf + stack size: The stack
• Last 0x40000000 bytes before 0xFFFF_8000_0000_0000 (where kernel addresses start): Maps to the frame buffer (if the user space process requests it)

I have a few ideas on how I can implement syscalls for the user space to have a global allocator:

Linear +/-

Heap address starts after the stack end. The user space can say to the kernel "I want 5 total pages" and the kernel will allocate some phys frames for the user space program and map the memory to those phys frames. The kernel will also remove from the end of the heap if the user space program requests for less pages than already exist.

User space requests the specific pages it wants

The user space program says to the kernel "I want this page range to be mapped to some fresh phys frames" and the kernel maps them.

[tsatke]

I'd say that the heap address is wherever the userspace program says the heap is. It requests memory with sys_mmap (or your equivalent) and can use that however it pleases. That syscall then allocates physical memory, maps it to the specified address and returns.