Date: Sat, 4 Mar 2000 20:39:13 +0100 From: "Marco van de Voort" <marcov@stack.nl> To: Hackers@freebsd.org Subject: Re: Can't write to stdout in assembly Message-ID: <20000304194140.48F3D2E803@hermes.tue.nl> In-Reply-To: <38C0EA12.A4252C20@mail.ptd.net>
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> >From what I understand, the following should print "Hello, world." on > stdout. I stole the code from the Linux HOWTO, but I think it should > work on FreeBSD as well. Instead, the call to write returns 9 (EBADF). I disassembled FreeBSD programs (create a small C prog, compile, and use objdump), and it looks more like this: (I haven't tested this yet, but it is definitely stack based, not register based, the part which I haven't tested is if the placing the int $0x80 behind a call is required) pusl $len pushl $Msg pushl $1 mov $4,%eax call _basicsyscall addl $12,%esp . . . _basicsyscall: int $0x80 ret > As a related question, can anyone point me to the source for the int > 0x80 handler? I've looked all over but can't find it. On the libc side? It is very fragmented in several files using a lot of macro code. If you wish I can look up the names for you (I did this some weeks ago) I never searched for the kernel side. (the actual 0x80 handler) Marco van de Voort (MarcoV@Stack.nl) <http://www.stack.nl/~marcov/xtdlib.htm>; To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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