A few noob question regarding system calls on x86/x64

[Aleksander Alekseev]

Hello.

Currently I'm exploring how system calls work in FreeBSD. For now I'm
interested only in x86 and x64 architectures and not considering Linux
ABI support. I've found a few good articles [1][2], however I would
like to clarify something:

* In general: 'int 80h' on x86, 'syscall' on x64 - right?
* Do I right understand that there is no such thing as system calls
  through 'sysenter' in FreeBSD?
* I've found a mentioning of vDSO in FreeBSD but there is little
  information on this topic. There is currently only one vDSO
  implementation in FreeBSD, not two like in Linux (vdso/vsyscall)?
  Where can I find more details on vDSO implementation?

[1]
https://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/x86-system-calls.html

[2]
https://thebrownnotebook.wordpress.com/2009/10/27/native-64-bit-hello-world-with-nasm-on-freebsd/

-- 
Best regards,
Aleksander Alekseev