Date: Tue, 20 Oct 1998 07:43:52 -0700 (PDT) From: David Wolfskill <dhw@whistle.com> To: grog@lemis.com Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Assembly Language Documentation Message-ID: <199810201443.HAA28327@pau-amma.whistle.com> In-Reply-To: <19981020111612.F433@freebie.lemis.com>
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>Date: Tue, 20 Oct 1998 11:16:12 +0930 >From: Greg Lehey <grog@lemis.com> >> Is any part of FreeBSD documented in assembly language? >I'm not sure if I understand you correctly. Assembly language is used >for programming, not documntation. Given the 12 years I spent as an MVS (IBM mainframe) systems programmer, I am forced to admit that I have a somewhat different perspective on this: there are environments and contexts in which assembly code is used to document such things as parameter lists and internal structures. Indeed, during that time, the system interfaces that were documented in any other way were quite rare: usually, the *only* supported interface to the OS was via assembly language "macros". (I did manage to write an assembly language routine that could be called by a C program, and which would invoke an arbitrary SVC (similar to a syscall), providing a parameter list that had been fabricated by the calling program. I was subsequently able to use this to accomplish an objective similar to the UNIX (courtesy of dmr) "setuid" flag on an executable -- with an arguably interesting wrinkle: I made the use of the facility dependent on the successful checking of an ACL for the particular program in question. And the UID to which the eUID was set wasn't dependent on static information such as the "owner" of the program. That was one of the more "interesting" bits of somewhat useful code I managed to cobble up in C in an MVS environment....) All that said, I certainly would *not* want to hold up the MVS approach to system interfaces as a model to emulate. :-} david -- David Wolfskill UNIX System Administrator dhw@whistle.com voice: (650) 577-7158 pager: (650) 371-4621 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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