RE: ia64 get_mmu_context patch

["Peter Keilty" <Peter.Keilty@hp.com>]

 Kenneth,

> -----Original Message-----
> From: Chen, Kenneth W [mailto:kenneth.w.chen@intel.com] 
> Sent: Thursday, October 27, 2005 11:24 PM
> To: 'Peter Keilty'; linux-ia64@vger.kernel.org
> Cc: 'Eric Whitney'
> Subject: RE: ia64 get_mmu_context patch
> 
> Peter Keilty wrote on Thursday, October 27, 2005 10:28 AM
> > Please find attached IA64 context_id patch and supporting data for 
> > your Review and consideration.
> > 
> > --- linux-2.6.14-rc3/arch/ia64/kernel/setup.c	
> 2005-10-26 10:54:06.000000000 -0400
> > +++ linux-2.6.14-rc3pmk/arch/ia64/kernel/setup.c	
> 2005-10-25 14:53:59.000000000 -0400
> > @@ -419,6 +419,7 @@
> > ...
> >  
> >  	/* set ia64_ctx.max_rid to the maximum RID that is 
> supported by all CPUs: */
> > -	if (ia64_pal_vm_summary(NULL, &vmi) = 0)
> > +	if (ia64_pal_vm_summary(NULL, &vmi) = 0) {
> >  		max_ctx = (1U << (vmi.pal_vm_info_2_s.rid_size 
> - 3)) - 1;
> > -	else {
> > +		if (max_ctx > (1U << 21)) {
> > +			max_ctx = (1U << 21) - 1;	/* 
> limit to 2^21  */
> > +			printk(KERN_WARNING "cpu_init: max_ctx 
> limited to 21 RID bits for bitmap size\n");
> > +		}
> > +	} else {
> 
> This printk is spurious.  When I first read it, my reaction 
> is: rid as in region register is architecturally defined at 
> maximum 24 bits.  Printing 21-bit for rid is misleading.  We 
> currently use 8 rid number per process.
> So 21 bit for context number is the max.  max_ctx will never 
> exceed 1<<21.
> Suggest this printk to be dropped.
I add that per mail with Tony, He suggested that we might limit the bitmap
size so that if the rid size was increase in future hardware that a Giga
byte 
Would not be allocated. The printk was to let people know that the rid was
being 
limited to 2^21 if the rid was enlarged.
> 
> - Ken
> 
>