Date: Tue, 22 Oct 1996 22:30:51 -0700 From: David Greenman <dg@root.com> To: johnson@charming.nrtc.northrop.com Cc: questions@FreeBSD.ORG Subject: Re: Virtual memory question: map first page? Message-ID: <199610230530.WAA02352@root.com> In-Reply-To: Your message of "Tue, 22 Oct 1996 22:14:59 MDT." <9610230515.AA02752@charming.nrtc.northrop.com>
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>I noticed that in imgact_aout.c the text segment gets mapped starting at >linear address 4096. Right. >Is it possible to map the first page of linear memory? What I would like >to be able to do is set up a process in which linear addresses starting >at 0 are mapped. Yes, it's possible. >When I modified imgact_aout.c to map the first linear page of memory as >an experiment, and then ran a specially cooked executable to exercise that >code, the machine immediately hung. Operator error. :-) >Is there something special on the first linear page of a user process? No. In fact if my memory isn't failing, the original "ZMAGIC" format of 386BSD (which we still support) maps the executable starting at virtual address 0 (although to skip over the image header, the file offset is 4096). -DG David Greenman Core-team/Principal Architect, The FreeBSD Project
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