# regarding system calls and kernel v8.1



## bronzebeard (Aug 30, 2010)

good day guys!
if finally get the guts to post in one of these forums after just browsing for a while now.... and hopefully my attitude towards programming is also positively progressing..
anyway freebsd! ive read pretty much the documentation and it was a long one. 
coming from a not so techie with minimal C programming background, you can understand what a painful process that was.. trying to understand things..

mods if im posting at wrong section please feel free to move this thread.

um guys if anyone would be so kind as to guide me on 'how i can add system call' i have had success on building and installing a custom kernel. but based only on what was written on the documentation. aside from that i dont have much clue as to the 'little things' that happen on the background while i make freebsd run my systemcall. 

sadly ive only gone so far as pre-syscalls.master... i always get error, do i replace a value there? or just add a new line? T_T a simple helloworld would make me very happy.

hope i dont get laughed at here.. i am really trying my best to understand new stuff aside from what they teach me in school.


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## eyebone (Aug 30, 2010)

hi,

fiddling around with system calls is quite funny. i do not have a example module here currently, but i would suggest you get "Designing BSD Rootkits", it was written for FreeBSD6 or 7, but you will get the idea pretty fast. 
If you speak german here is a link to a talk which gives a short overview about some things you can do, there is example code as well

http://ftp.ccc.de/events/gpn10/gpn10-appcontrol.mkv

btw. iirc there is example module code for simple modules in freebsd sourcetree as well,i do not remember the place but there was something like that.

good luck and have fun,


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## bronzebeard (Aug 31, 2010)

thank you kind sir!
sadly i dont know german.. but i will check that link out nonetheless

does implementing new system calls entail usage of the modular aspects of freebsd?
can i not just add system call as it is? and then build kernel? 

if i understand the texts. it is in assembly? T_T assembly gives more headaches LOL


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