Re: TSCs are a no-no on i386

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

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On Wed, 2003-07-30 21:01:00 +0100, Alan Cox <alan@lxorguk.ukuu.org.uk>
wrote in message <1059595260.10447.6.camel@dhcp22.swansea.linux.org.uk>:
> On Mer, 2003-07-30 at 19:45, Adrian Bunk wrote:
> >   Note that this can also allow Step-A 486's to correctly run multi-thread
> >   applications since cmpxchg has a wrong opcode on this early CPU.
> > 
> >   Don't use this to enable multi-threading on an SMP machine, the lock
> >   atomicity can't be guaranted!
> 
> The bigger problem (and certainly with some of the cmov emulation hacks
> I've seen) is getting the security checking right when you need to
> reprocess the user data - another reason to do it in userspace with a
> preload 8)

Well... For sure, I can write a LD_PRELOAD lib dealing with SIGILL, but
how do I enable it for the whole system. That is, I'd need to give
LD_PRELOAD=xxx at the kernel's boot prompt to have it as en environment
variable for each and every process?

That sounds a tad inelegant to me. Really, I'd prefer to see libstdc++
be compiled for i386 ...

...and IFF those new opcodes bring _that_ much performance, then we
should think about another Debian distribution for i686-linux. Up to
now, I was really proud of having _one_ distribution that's basically
capable of running on all and any machines I own...

MfG, JBG

-- 
   Jan-Benedict Glaw       jbglaw@lug-owl.de    . +49-172-7608481
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