Date: Mon, 16 Jan 2012 07:13:57 +0100 From: "Julian H. Stacey" <jhs@berklix.com> To: "Conrad J. Sabatier" <conrads@cox.net> Cc: freebsd-questions@freebsd.org Subject: Re: COMPAT_* kernel config options -- some housecleaning overdue? Message-ID: <201201160614.q0G6DvjH012679@fire.js.berklix.net> In-Reply-To: Your message "Sun, 15 Jan 2012 19:13:34 CST." <20120115191334.385bd3eb@cox.net>
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Hi, "Conrad J. Sabatier" wrote: > I've been wondering for a while now about the accuracy of some of the > comments in /sys/conf/NOTES re: the various COMPAT_* options, and now, > with 9.0-RELEASE already out the door and 10.0-CURRENT as the current > development branch, it seems even more relevant to ask just how > necessary or useful some of these options are anymore. > > Let me preface the following by saying that I just recently built a > 10.0-CURRENT kernel with no COMPAT_* options besides COMPAT_FREEBSD32 > and COMPAT_LINUX32, and everything seems to be working just fine (yes, > including Linux emulation). > > First and foremost, the comment re: COMPAT_43: "You probably do NOT > want to remove this as much current code still relies on the 4.3 > emulation." This might not be just refering to code runing on FreeBSD, but perhaps also code running on older other legacy net machines ? I suspect I may have needed it to talk to eg my Symmetric 375 (a 4.2BSD Bill Jollitz product pre 386BSD pre FreeBSD http://www.berklix.com/~jhs/symmetric/ ) (Not that I put that comment in), it might be an ifdef that allows adaptive detection of logic low & high for TCP broadcast address ? Whatever, searching & updated comments on what they all do would be nice. Feel free to search the source with find & grep & use send-pr to update the comments, would be useful :-) cd /usr/src vi -c/COMPAT_43TTY `find . -type f -exec grep -l COMPAT_43TTY {} \;` dmesg .... > This would appear to no longer be true. And similarly, > how relevant or viable is COMPAT_43TTY anymore? Why would one want to > use this? To support legacy code/ apps. Warning "There be dragons" as it says on old maps ;-) ie tty in Unix has traditionaly been a complex place to mess around, personaly I'd stear clear & leave it to those willing to futz about with tty :-). > I suspect that neither of these options has any real effect > anymore and both may, in fact, be essentially NOOPs. How close to the > real picture is that? > > It is my understanding that, on 64-bit platforms, COMPAT_FREEBSD32 > *is* necessary if COMPAT_LINUX32 is enabled, which seems perfectly > reasonable. However, the comment accompanying COMPAT_LINUX32 states > that COMPAT_43 is also required, which simply is not true. > And speaking of Linux compatibility, we still have an erroneous reference to > COMPAT_LINUX instead of COMPAT_LINUX32 accompanying 'device tdfx'. dmesg then > Then, of course, there are the various COMPAT_FREEBSD[4-7] options, > each accompanied by a comment which merely states the obvious but > offers no real clue as to whether or not any of them are actually > necessary. was mentioned on another list in last few days > I don't know, this whole COMPAT area just seems really messy to me -- > disorganized, unclearly documented and probably suffering from no small > amount of bit rot and neglect. I really do think it's time for some > cleaning up. > > Hope I didn't ruffle any feathers, but I just hate this type of gray > fuzziness. Clarification (maybe even some deprecation?) seems to be in > order here. Yup, certainly needs clearer comments ... find ... grep ... vi ... dmesg :-) Cheers, Julian -- Julian Stacey, BSD Unix Linux C Sys Eng Consultants Munich http://berklix.com Reply below not above, cumulative like a play script, & indent with "> ". Format: Plain text. Not HTML, multipart/alternative, base64, quoted-printable.
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