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-# Hello dynamic linking
-
-In `dynamic linking` a program can use code that is not contained in the
-program file itself but rather in separate library files, so called shared
-objects.
-
-In comparison a statically linked program contains all the `code` & `data` that
-it needs to run from start until completion. The program will be loaded by the
-Linux Kernel from the disk into the virtual address space and control is handed
-over to the mapped program which then executes.
-```text
-                          @vm
-                         |        |
- @disk                   |--------|
-+--------+   execve(2)   |        | <- $rip
-| prog A | ------------> | prog A |
-+--------+               |        |
-                         |--------|
-                         |        |
-```
-
-A dynamically linked program on the other hand needs to specify a `dynamic
-linker` which is basically a runtime interpreter. The Linux Kernel will additionally load
-that interpreter into the virtual address space and give control to the
-interpreter rather than the user program.
-The interpreter will prepare the execution environment for the user program by
-for example loading dependencies and running initialization routines. After the
-environment is set up the dynamic linker passes control to the user program.
-```text
-                                @vm                      @vm
-                               |        |               |          |
- @disk                         |--------|               |----------|
-+--------------+   execve(2)   |        |               |          | <- $rip
-| prog A       | ------------> | prog A |               | prog A   |
-+--------------+               |        |   load deps   |          |
-| interp ldso  |               |--------| ------------> |----------|
-+--------------+               |        |               |          |
-| dep libgreet |               |--------|               |----------|
-+--------------+               | ldso   | <- $rip       | ldso     |
-                               |--------|               |----------|
-                                                        |          |
-                                                        |----------|
-                                                        | libgreet |
-                                                        |----------|
-```
-> NOTE: Technically the Linux Kernel does not need to load the dynamically
-> linked user program itself, but that detail is not important here.
-
-In the `ELF` binary format the name of the dynamic linker is specified as a
-string in the special section `.interp`.
-```bash
-readelf -W --string-dump .interp main
-
-String dump of section '.interp':
-  [     0]  /lib64/ld-linux-x86-64.so.2
-```
-
-The `.interp` section is referenced by the `PT_INTERP` segment in the program
-headers. This segment is used by the Linux Kernel during the `execve(2)`
-syscall in the [`load_elf_binary`][load_elf_binary] function to check if the
-program needs a dynamic linker and if so to retrieve its name.
-```bash
-readelf -W --sections --program-headers main
-
-Section Headers:
-  [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
-  [ 0]                   NULL            0000000000000000 000000 000000 00      0   0  0
-  [ 1] .interp           PROGBITS        00000000000002a8 0002a8 00001c 00   A  0   0  1
-  ...
-
-Program Headers:
-  Type           Offset   VirtAddr           PhysAddr           FileSiz  MemSiz   Flg Align
-    PHDR           0x000040 0x0000000000000040 0x0000000000000040 0x000268 0x000268 R   0x8
-    INTERP         0x0002a8 0x00000000000002a8 0x00000000000002a8 0x00001c 0x00001c R   0x1
-        [Requesting program interpreter: /lib64/ld-linux-x86-64.so.2]
-    ...
-```
-
-With the use of `gdb` it can be easily verified that the control is first
-passed to the dynamic linker and not the user program. This is shown by
-stopping at the first instruction of the new process (`starti`) and examining
-the backtrace (`bt`). Where `ld-linux-x86-64.so` is the dynamic linker as shown
-in the `.interp` section above.
-```bash
-gdb -q --batch -ex 'starti' -ex 'bt' ./main
-
-Program stopped.
-0x00007ffff7fd2090 in _start () from /lib64/ld-linux-x86-64.so.2
-#0  0x00007ffff7fd2090 in _start () from /lib64/ld-linux-x86-64.so.2
-#1  0x0000000000000001 in ?? ()
-#2  0x00007fffffffe43e in ?? ()
-#3  0x0000000000000000 in ?? ()
-```
-> NOTE: Frames `#1 - #3` don't actually exist, gdb's unwinder just tried to further unwind the stack.
-
-## Things to remember
-- Dynamically linked programs use code contained in separate library files.
-- The `dynamic linker` is an interpreter loaded by the Linux Kernel and gets
-  control before the user program.
-- A dynamically linked program specifies the dynamic linker needed in the
-  `.interp` section.
-
-[load_elf_binary]: https://elixir.bootlin.com/linux/v5.9.8/source/fs/binfmt_elf.c#L850