[lfs-support] How processor-specific is a standard LFS build?

Bruce Dubbs bruce.dubbs at gmail.com
Fri Aug 17 08:59:39 PDT 2012


Ken Moffat wrote:
> On Fri, Aug 17, 2012 at 07:53:38AM -0500, Eleanore Boyd wrote:
>> That would depend on how far back you're interested in going, and
>> how much you're willing to look into it. For compatibility with most
>> things, you would be interested in getting a "i386-pc-linux-gnu"
>> target triplet, which might involve getting older packages, or
>> setting some options in the environment prior to building anything.
>>
>   I believe fedora and debian do something like this.  In LFS, we
> have a note on the glibc page: Because Glibc no longer supports i386,
> its developers say to use the compiler flag -march=i486 when
> building it for x86 machines.
>
>> On a side note, to be compatible with almost all IBM based
>> computers, I think you're looking at getting, say,
>> "i086-pc-linux-gnu" or "i186-pc-linux-gnu" as those would correspond
>> to the earliest days of the Intel instruction set.
>>
>> Elly
>
>   *smiles* - nice idea.  This is now old history (my first
> pc-compatible used a 286, before that I'd used Z80 machines), but
> anything capable of running linux always needed to be 386 or
> greater.  When I started using linux (late 1999), I had some
> 586-class machines (original pentium, and AMD K6.  With very rare
> exceptions (some of the early VIA processors), anything from recent
> years will be 686.

Right. On of the primary goals of Linux was to use 32-bit addresses, not 
the 16:16 (effectively 20 bit) addresses of the 8086 and 80286.

I think the main issue of building for older '386 systems would be the 
kernel drivers and other configuration settings, but running anything, 
even a command line, would be incredibly slow.  I think the '386 systems 
peaked out at about 100MHz.

   -- Bruce



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