Date: Tue, 9 Nov 2004 09:41:25 +0200 From: Andrey Simonenko <simon@comsys.ntu-kpi.kiev.ua> To: Dan Strick <strick@covad.net> Cc: freebsd-hackers@freebsd.org Subject: Re: Where is the source to the system calls? Message-ID: <20041109074125.GB238@pm514-9.comsys.ntu-kpi.kiev.ua> In-Reply-To: <200411081857.iA8Iv725000576@mist.nodomain> References: <200411081857.iA8Iv725000576@mist.nodomain>
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On Mon, Nov 08, 2004 at 10:57:07AM -0800, Dan Strick wrote: > > Perhaps I did not make it clear that I was looking for the definitions > of the subroutines in libc that converted C-language function calls, > such as open(), into assembler language system calls. For example, in > version 7 pdp11 unix, the open() system call was defined in the very > straight forward assembler language program /usr/src/libc/sys/open.s: [ skipped ] Almost the same is done in FreeBSD, but under i386 int $0x80 is a trap gate for system calls (search int0x80_syscall in /sys/i386/i386/exception.s). If that SYS.h is unclear for you for the first time, so read paragraphs about x86 Assembler and syscalls in Developers' Handbook. > I still don't understand all the details but I do understand enough > to realize that I don't want to understand any more. Assembler sources for syscalls are created from the src/lib/libc/sys/ Makefile.inc file. Find #include "SYS.h" in this file. The names of syscalls are generated from the /sys/sys/syscall.mk, which is generated from sys/kern/syscalls.master. Try to discover how this works backtracing Makefile.inc from the line with #include "SYS.h".
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