Re: TSCs are a no-no on i386

[Jan-Benedict Glaw <jbglaw@lug-owl.de>]

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On Thu, 2003-07-31 11:50:27 -0400, Richard B. Johnson <root@chaos.analogic.com>
wrote in message <Pine.LNX.4.53.0307311126530.770@chaos>:
> On Thu, 31 Jul 2003, Jamie Lokier wrote:
> > Willy Tarreau wrote:

> The bad op-code for the i386 is cmpxchg. This is what triggers
> the trap. This can be emulated, although the emulation is
> not SMP compatible. You worry about this when somebody makes
> a dual '386 machine ;^).  Also, the best performing emulation
> for any op-codes should be done within the kernel. That way,
> the invalid-opcode trap works just like the math emulator. You
> don't need the overhead of calling a user-mode handler. If
> this is emulation is implimented, then one should also emulate
> BSWAP and XADD. This makes '486 code compatible with '386
> machines.

Thanks for this fine explanation! Maybe I'd take the 2.4.x emulator
kernel patch and bring it in line with 2.6.x?

However, that doesn't release gcc's developers from providing a solution
to the initial problem (i386 and i486 compiled libs/programs
incompatible) from the task to work on libstdc++ :->

MfG, JBG

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