I started coding in vhdl and I'm currently using emacs with its vhdl mode as editor on Ubuntu 16.04 OS. However i was wondering if its possible to start emacs already in vhdl mode, meaning I won't have to enable the vhdl mode every time after starting emacs (m-x vhdl-mode).
Emacs as a whole doesn't have a "vhdl-mode", because you can use several buffers at the same times in the same Emacs session, with some buffers using vhdl-mode while others use verilog-mode.
The mode used for a file is usually decided based on the file name, using
auto-mode-alist. So what you want to do is to make sure your files have names that are recognized as "files using vhdl-mode" by
If your file names have the shape
<foo>.vhd then Emacs should automatically use
vhdl-mode for them. If your file names look different (e.g. they have the shape
<foo>.myext), then explain it to Emacs:
(add-to-list 'auto-mode-alist '("\\.myext\\'" . vhdl-mode))