How Linux platforms are switched, i386 to i686 ?
When Linux kernels were strictly 2.4.x; drivers were in /dev. The ascii codes were strictly teleptype. Xvesa vga 791 and 792 were i386 platform. You can use i386, 486, 586 cpus and better.
In Linux kerenl 2.6.x, drivers are udev in /usr; the video drivers were changed to Xorg. The ascii codes wre i686 instructions. Since the console is the operating system, the entire operating system is restricted to i686 ascii codes. The platform change, forced people to use Pentium I and better. When you use Pentium 4 or better, you have ambiguous video chipset with Analog Devices DSP cpu. So, the ATi, Nvidia and Intel video chipset all require i686 platform.
Now, we know how platform and i386 was changed to i686 performance. Much faster video and computations.
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Linux platforms at a cross road ?
First, Xvesa vga 791 is i386 but vga 792 is i686 platform.
We now realize that Linux kernel 2.4.x applications are all i386 platform.
To set speed, up to i686, all the applcations had to be using ascii codes with i686 instructions.
You will not speed up drupal until you use i686 optimized applications.
So, you have to go to each Linux project and request an i686 version to be used with Linux kernel 2.6.x? Basically, everytime you use a driver, you have to send it an i686 instruction and never an i386 instruction.
re: Linux platforms at a cross road
Hmm, interesting.
Isn't compiling applications from source for i686 (almost) the same?
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You talk the talk, but do you waddle the waddle?
AMD 64bit (Alpha/Mips hypertransport pipelines) ?
The reason that we look at the basic instructions is the ever changing specofocations. We have the "write back" in K6-2 cpu and the 3D now also. Then h6-3/k7 had the extra L2 cache and L3 cache? But there are 3 hypertranport pipelines. So, is that i686 exactly? You need to compile to AMD_64 instructions?
Going back to i686, Intel had branch prediction, MMX first then SSE for sound. Video has codecs(data compression) but rendering machines and other hardware chipset had their own instructions. This brings applications to needing mostly multimedia instructions added to i386 platform.
So, the compiling to i686 platform has to examine the real cpu you are using, with the underpining instructions you need for maximum speed.
Debian is kernel independent ?
The main feature of Debian has always been kernel independency. which means kernels can be re-written. This means platform is the major dependency. The ascii codes always include the instructions and data according to the cpu features. Then you may change the kernel drivers to get hardware compatibility. The kernels do include ethernet dhcp, so that can be changed too for wifi, etc in dhcpcd. Drivers are backward compatible to xvesa vga, soundblaster Pro and external modem; therefore independent of driver changes. Most distro now revert back to /dev drivers unless you install 2.6.x kernels, that replaces one /dev driver with xorg(i686 platform only). Later you can replace all /dev drivers with /usr drivers.
When we examine the Linux 2.6.x kernels. It has not define the platform except xorg(Nvidia, ATI, Intel video) is i686 preferred. But hotplug of USB devices changed drivers. And ambiguous devices will be installed by udev. The driver files are in /usr for your own ambiguous devices(not anyone else's as in /dev).
So, you notice the popularity of Debian and its derivatives. It is much easier to use Debian to streamline Linux kernel 2.6.x and we still have a lot of work ahead of us on applications which is platform dependent but not kernel dependent. Changing drivers will mean applications have to have new instruction sets enabled, and become kernel dependent as in Ubuntu(computers have to be certified with specific components).
Footnote:
Windows sounblaster application installs drivers at address 220, IRQ5 and DMA=2, thereby not dependent on windows for drivers. Debian does the same thing on applications to be kernel independent. Burner application software are not kernel dependent?