1:N threading

[Jake Burkholder]

Apparently, On Thu, Apr 03, 2003 at 09:29:11PM -0500,
	Jake Burkholder said words to the effect of;

> Apparently, On Thu, Apr 03, 2003 at 03:35:41PM -0800,
> 	Peter Wemm said words to the effect of;
> 
> > Daniel Eischen wrote:
> > 
> > > The patches are available:
> > > 
> > >   http://people.freebsd.org/~deischen/libpthread.diffs
> > > 
> > > FYI, since this is a new mailing list, the above changes
> > > are meant to give libpthread M:N capability.
> > > 
> > > I don't need testers; I have enough bugs that I know about
> > > to fix.
> > 
> > +	__asm__("movl %%gs, %0" : "=r" (id));
> > +	id >>= 3;
> > +	if (id - NLDT < 0)
> > 
> > There is a problem here, NLDT is kernel private and changes depending on
> > things like whether SMP is enabled or what the maximum number of cpus
> > is.
> > 
> > You're trying to find if its a local or global selector, right?
> > What you really want is bit 2 which tells you which it is.
> > 
> > #define ISLDT(s)        ((s)&SEL_LDT)   /* is it local or global */
> > #define SEL_LDT 4               /* local descriptor table */
> 
> NLDT seems to be invariant, but we should have a sysctl or something to
> get the first LDT entry that is unused by the kernel.  Libthr uses it
> in order to know which entry to start at.

Actually Dan uses it for the exact same thing :)

Jake