Re: [boost] Default x86 instruction set

Subject: Re: [boost] Default x86 instruction set
From: Jonathan Wakely (jwakely.boost_at_[hidden])
Date: 2013-05-07 13:37:47

On 7 May 2013 17:17, Andrey Semashev wrote:
>
>> I also think it shouldn't do that. I suppose the reason is due to a
>> limitation of Boost.Build that needs to know what the default is.
>> Most GCC 32-bit binaries will build for i386 by default, even on modern
>> linux distributions.
>
> Not for Ubuntu 13.04, at least.
>
> gcc -m32 -dM -E - < /dev/null | grep __i686__
> #define __i686__ 1
>
> I also read that Fedora and Mandriva moved to i686 by default (probably, emulating
> cmov in kernel if running on i586) [1].
>
> And Linux kernel dropped support for 80386 CPUs. [2] I actually read they dropped all
> CPUs without cpuid (which also includes some 80486) somewhere else, but I can't find it
> now. FreeBSD removed support for 80386 in 6.0 ([3], [4]). OpenBSD doesn't support
> both 80386 and some 80486 [5].

NetBSD dropped 80386 support too:
http://mail-index.netbsd.org/tech-toolchain/2009/02/24/msg000582.html