Re: TSCs are a no-no on i386

From: Jan-Benedict Glaw (jbglaw@lug-owl.de)
Date: Wed Jul 30 2003 - 15:28:22 EST

On Wed, 2003-07-30 20:45:29 +0200, Adrian Bunk <bunk@fs.tum.de>
wrote in message <20030730184529.GE21734@fs.tum.de>:
> On Wed, Jul 30, 2003 at 11:30:33AM -0700, Mike Fedyk wrote:
> > On Wed, Jul 30, 2003 at 08:10:06PM +0200, Adrian Bunk wrote:
> > > On Wed, Jul 30, 2003 at 03:56:23PM +0200, Jan-Benedict Glaw wrote:
> > > > Please apply. Worst to say, even Debian seems to start using i486+
> > > > features (ie. libstdc++5 is SIGILLed on Am386 because there's no
> > > > "lock" insn available)...
> > >
> > > Shouldn't the 486 emulation in the latest 386 kernel images in Debian
> > > unstable take care of this?
> >
> > What emulation?
>
> 486 emulation
> 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. 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)

libstdc++ (and it's main user, apt-get) break at a LOCK insn.

MfG, JBG 

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