> Il giorno 05 mar 2017, alle ore 18:24, John Baldwin <j...@freebsd.org> ha > scritto: > > On Saturday, March 04, 2017 08:14:11 PM Pedro Giffuni wrote: >> >> 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 <j...@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. > > So I would rather support 486 in GENERIC or not support it at all. It doesn't > cost anything for it to be in GENERIC, so if we have it, I think we should > ship > it. Also, the original justification for this commit of a 4% performance gain > doesn't seem to have any basis in fact. The one gain I can think of is > de-cluttering some things like identcpu.c and initcpu.c which can only happen > if > we remove code entirely, not from removing an option in GENERIC. >
OK, that’s reasonable. I will revert the change. Pedro. _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
