svn commit: r314669 - head/sys/i386/conf

[Pedro Giffuni]

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 at 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.