Re: X15 alpha release: as fast as TUX but in user space (fwd)

[Pavel Machek <pavel@suse.cz>]

Hi!

> > > > Whatever happened to that hack that was discussed a year or two ago?
> > > > The one where (also on IA32) a magic page was set up by the kernel
> > > > containing code for fast system calls, and the kernel would write
> > > > calibation information to that magic page. The code written there
> > > > would use the TSC in conjunction with that calibration data.
> 
> >                                                                 Pavel
> > PS: Hmm, how do you do timewarp for just one userland appliation with
> > this installed?
> 
> 1. Kernel solution: give that particular process a different magic page
> 2. User solution:   Don't obtain time from the magic page.
> 2a                  By changing program source, if available
> 2b                  By switching the c library, assuming it is used

That means that for fooling closed-source statically-linked binary,
you now need to patch kernel. That's regression; subterfugue.org could
do this with normal user rights in 2.4.0.
-- 
I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org