Baslinux mailing list

[Rainer Desor <renkaba AT gmx.de>]

On Thu, 18 May 2006 08:15:17 -0700, David Moberg <davidjmoberg AT gmail.com> 
wrote:

> Perhaps the busybox binary contains 486 instructions, which the 386
> does not know how to execute. I wonder if the following kernel feature
> would help? If I built a kernel with it, would you be willing to test
> it?
>
> CONFIG_CPU_EMU486
> When used on a 386, Linux can emulate 3 instructions from the 486 set.
> This allows user space programs compiled for 486 to run on a 386
> without crashing with a SIGILL [Illegal instruction]. As any emulation,
> performance will be very low, but since these instruction are not often
> used, this might not hurt.  The emulated instructions are:
>    - bswap (does the same as htonl())
>    - cmpxchg (used in multi-threading, mutex locking)
>    - xadd (rarely used)

Hi David,

I guess you are right. Especially internet related commands create 
'illegal instruction' error.
AFAIK the instruction BSWAP is not part of the 386 instruction set and 
might be used
by buysbox to change byte-order from pc to network. Usually htonl() is 
used, but BSWAP
might be faster or smaller code. Would be nice to have busybox for 386 
instead of replace parts with slackware.

regards

Rainer


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Rainer Desor / Bovenden / Germany