*BSD News Article 28471


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From: zheng@golem.wcc.govt.nz (Chuck Zheng)
Newsgroups: comp.os.386bsd.questions
Subject: NetBSD-0.9 LCALL
Date: 20 Mar 1994 22:08:17 +1200
Organization: Wellington City Council
Lines: 20
Message-ID: <2mh7ah$jf8@golem.wcc.govt.nz>
NNTP-Posting-Host: golem.wcc.govt.nz

Hello,

I have been trying to figure out how does system call works on
NetBSD-0.9, and found LCALL(0x7,0x0) being used in several related
places. It is a macro def to ".byte 0x9a .long 0 .word 0x7". 
According to my understanding of 386, this maps to a "call" instruction
with selector 0 from LDT, and request-privilige-level=3 and displacement
from the selector base address being 0.  Can somebody please tell me,

1. do I interpret it correctly?

2. If so, how is the LDT descriptor 0 set up? why RPL=3?

BTW, where do I get GAS man page for 386?

Thanks in advance,

cheers
chuck