Date: Sat, 4 Mar 2017 20:14:11 -0500 From: Pedro Giffuni <pfg@FreeBSD.org> To: John Baldwin <jhb@freebsd.org> Cc: Slawa Olhovchenkov <slw@zxy.spb.ru>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r314669 - head/sys/i386/conf Message-ID: <c5fc59db-3d9a-92f9-0e10-e9002b38b9f8@FreeBSD.org> In-Reply-To: <7873439.f6BlOXHt6g@ralph.baldwin.cx> References: <201703041504.v24F4HMh023937@repo.freebsd.org> <2368011.hGEX4V32U5@ralph.baldwin.cx> <D81029FA-61CF-4648-A2A8-8570DEF28B14@FreeBSD.org> <7873439.f6BlOXHt6g@ralph.baldwin.cx>
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On 3/4/2017 5:51 PM, John Baldwin wrote: > On Saturday, March 04, 2017 03:49:52 PM Pedro Giffuni wrote: >>> Il giorno 04 mar 2017, alle ore 14:43, John Baldwin <jhb@freebsd.org> ha scritto: >>> >>> On Saturday, March 04, 2017 10:52:46 AM Pedro Giffuni wrote: >>>> On 03/04/17 10:32, Slawa Olhovchenkov wrote: >>>>> On Sat, Mar 04, 2017 at 03:04:17PM +0000, Pedro F. Giffuni wrote: >>>>> >>>>>> Author: pfg >>>>>> Date: Sat Mar 4 15:04:17 2017 >>>>>> New Revision: 314669 >>>>>> URL: https://svnweb.freebsd.org/changeset/base/314669 >>>>>> >>>>>> Log: >>>>>> Drop i486 from the default i386 GENERIC kernel configuration. >>>>>> >>>>>> 80486 production was stopped by Intel on September 2007. Dropping the 486 >>>>>> configuration option from the GENERIC kernel improves performance >>>>>> slightly. >>>>>> >>>>>> Removing I486_CPU is consistent at this time: we don't support any >>>>>> processor without a FPU and the PC-98 arch, which frequently involved i486 >>>>>> CPUs, is also gone so we don't test such platforms anymore. >>>>> What is realy mean? >>>> This means we don't do work-arounds that would be required for raw 486. >>>> Instead we will use the 586 instructions by default. >>> This doesn't change that. The kernel already has runtime tests in place >>> for new things on 486 and later via cpuid. >>> >> Hmm ..then I am wondering if I effectively changed anything? > The only change is a 486 now panics on boot when it used to work fine. :-/ > > Nothing for other CPUs has changed. Not much has been lost then. FWIW, I have a "Pentium overdrive" somewhere in the basement which could theoretically boot FreeBSD 12 but last I remember just rebuilding a kernel was painful and the memory and HD limitations really make it a no-go. > >> The number came out from an old posting involving buildworld times, which I can’t find now :(. >> Things seem to have changed a lot: it was surely using GCC back then, I don’t believe clang does much distinction about 486 at all. >> >> BTW, does it make sense to keep i586 in the configuration still? Both i486 and i586 were once removed but later re-instated in r205336. > If anything I'd probably say we should do what bde@ suggested and just > remove CPU class entirely (and act as if 486, 586, and 686 are always > defined). > In any case ... I won't MFC the change and if someone asks me to revert it I will (I'd love to see a dmesg first ;) ). Pedro.
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