Add todo

TODO.md

@@ -0,0 +1,26 @@
+# TODO
+
+## Global
+
+- Port to ARM (using NEON in place of SSE)
+
+- GCC 9: test flags before ?
+  
+  ```/usr/lib/gcc/x86_64-linux-gnu/9/include/mwaitxintrin.h:41:1: error: '-mindirect-branch' and '-fcf-protection' are not compatible```
+
+## Spectre_v2 
+
+- Use `size_t` instead of `char*` for _target_addr_
+
+## Makefile
+
+- `$REVISION`: use `cat .git/refs/heads/main` instead of `git rev-short`:
+  
+  ```
+  fatal: unsafe repository ('/tmp/octopus' is owned by someone else)
+  To add an exception for this directory, call:
+    git config --global --add safe.directory /tmp/octopus
+  fatal: unsafe repository ('/tmp/octopus' is owned by someone else)
+  To add an exception for this directory, call:
+    git config --global --add safe.directory /tmp/octopus
+  ```