About mtune=atom

[John Reiser]

On 01/24/2011 07:43 AM, drago01 wrote:
> On Mon, Jan 24, 2011 at 3:32 PM, Sergio Belkin <sebelk at gmail.com> wrote:
>> Hi,
>>
>> I've read on http://fedoraproject.org/wiki/Packaging:RPMMacros#Build_flags_macros_and_variables
>> that mtune=atom. Just because I'm curious, why?  :)
> 
> Why not?
> 
> It is the only 32bit only CPU still being sold, 

There are plenty of machines with 32-bit only CPUs (such as early Celeron,
Pentium socket 478, even some Core Duos [Apple Mini]) which run Fedora very well.
Many are less than 5 years old. In the US, that means the depreciation rules
of tax law strongly encourage their continued use.

> and it does not seem
> to hurt others anyway (and most of them should use x86_64 anyway),

Actually many of them should be using the new x86_32 software architecture,
which is the 64-bit instruction set (thus 16 "general" registers, SSE, ...)
but with integers, longs, and pointers all 32 bits.  The upper 32 bits
of any user address are 0, and not stored in RAM (except the return address
of CALL.)  This gives a measurable benefit on boxes with low RAM.

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