os-tutorial/22-malloc

Concepts you may want to Google beforehand: malloc

Goal: Implement a memory allocator

We will add a kernel memory allocator to libc/mem.c. It is implemented as a simple pointer to free memory, which keeps growing.

The kmalloc() function can be used to request an aligned page, and it will also return the real, physical address, for later use.

We'll change the kernel.c leaving all the "shell" code there, Let's just try out the new kmalloc(), and check out that our first page starts at 0x10000 (as hardcoded on mem.c) and subsequent kmalloc()'s produce a new address which is aligned 4096 bytes or 0x1000 from the previous one.

Note that we added a new strings.c:hex_to_ascii() for nicer printing of hex numbers.

Another cosmetic modification is to rename types.c to type.c for language consistency.

The rest of the files are unchanged from last lesson.