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Bug#198158: architecture i386 isn't i386 anymore

On Fri, Jun 20, 2003 at 09:51:07AM +0200, Matthias Klose wrote:
> The solution I would favour would be:
> - drop the i386 support
> - keep the i386 architecture name
> - let dpkg-architecture output the new configuration string
>   (i.e. i486-linux)
> - if anybody wants to start the mini-i386 architecture, we have to
>   find an architecture name for it.
> changing the dpkg-architecture's ARCH string to i.e. i486 would break
> a lot of build scripts ...
> comments welcome.
> Hmm... I'm not sure about this as the last time I used assembler was 
> in the times of real mode DOS, but there is a yet another option:
> we can patch the kernel so when an invalid opcode occurs, whatever 
> instruction was at CS:EIP gets emulated in software, similar to the
> way i387 emulation is done.
> (arch/i386/kernel/entry.S)
> Of course, this would further slow down the speed demon known as 80386,
> but since (AFAIK) the 486-specific opcodes get used pretty rarely in 
> non-kernel code, the performance hit wouldn't be crippling.  And, there
> is no performance hit at all for >386 machines, as no legitimate process
> ever triggers the invalid opcode fault.

If this indeed feasible, then this is the solution that appeals most to
me personally.

* It seems the least intrusive.  80386 users are probably going to want
  and use an 80386-specific kernel, if they don't already *have* to.
* Our hand is forced by the fact that the rest of the Linux distributors
  in the world, and apparently the GCC folks, don't care about C++ ABI
  portability to 80386 processors.
* This doesn't require recompiling anything except the kernel.

The drawbacks:
* Someone actually has to write this kernel patch.

Also, Herbert Xu, the 80386 kernel-flavor maintainer, would have to be
agreeable, and I don't believe I saw him offer an opinion on this
approach in this discussion.

I believe it would be a mistake to kill off support for the 80386 chip.

G. Branden Robinson                |      "There is no gravity in space."
Debian GNU/Linux                   |      "Then how could astronauts walk
branden@debian.org                 |       around on the Moon?"
http://people.debian.org/~branden/ |      "Because they wore heavy boots."

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