Re: [RFC PATCH 3/3] x86-64: Calgary IOMMU - hook it in

[Jon Mason <jdmason@us.ibm.com>]

On Wed, Mar 15, 2006 at 12:26:12AM +0100, Pavel Machek wrote:
> On ?t 14-03-06 17:22:48, Jon Mason wrote:
> > On Wed, Mar 15, 2006 at 12:03:48AM +0100, Pavel Machek wrote:
> > > On ?t 14-03-06 10:26:34, Muli Ben-Yehuda wrote:
> > > > This patch hooks Calgary into the build and the x86-64 IOMMU
> > > > initialization paths.
> > > > 
> > > > Signed-Off-By: Muli Ben-Yehuda <mulix@mulix.org>
> > > > Signed-Off-By: Jon Mason <jdmason@us.ibm.com>
> > > > 
> > > > diff -Naurp --exclude-from /home/muli/w/dontdiff iommu_detected/arch/x86_64/Kconfig linux/arch/x86_64/Kconfig
> > > > --- iommu_detected/arch/x86_64/Kconfig	2006-03-14 08:58:23.000000000 +0200
> > > > +++ linux/arch/x86_64/Kconfig	2006-03-12 10:49:04.000000000 +0200
> > > > @@ -372,6 +372,16 @@ config GART_IOMMU
> > > >  	  and a software emulation used on other systems.
> > > >  	  If unsure, say Y.
> > > >  
> > > > +config CALGARY_IOMMU
> > > > +	bool "IBM x366 server IOMMU"
> > > > +	default y
> > > > +	depends on PCI && MPSC && EXPERIMENTAL
> > > > +	help
> > > > +	  Support for hardware IOMMUs in IBM's x366 server
> > > > +	  systems. The IOMMU can be turned off at runtime with the
> > > > +	  iommu=off parameter. Normally the kernel will make the right
> > > 
> > > Runtime? I think you meant boottime.
> > 
> > Yes, thanks for pointing it out.
> > 
> > > 
> > > > +	  choice by itself.  If unsure, say Y.
> > > 
> > > Eh? How common are those machines?
> > 
> > While this code is specific to IBM's xSeries systems, it will not hurt
> > to have it enabled on other systems.  The code is intelligent enough to 
> > detect the existence of Calgary chips and, if not there, will go down 
> > the standard path of no-iommu (providing that swiotlb has not been
> > specified at boottime).  If this isn't clear enough in the description,
> > I can remedy that.
> 
> No, it was pretty clear. But unless these machines are pretty common,
> I'd suggest users to say N. ... its like most drivers, it takes space
> but no other harm. Still we don't want to say "say Y" on all drivers.

Ah, I understand your point now.  I'll fixup the comment and default value.

> ...it is not required for boot on IBM x366 machines, is it?

No, it is not.

Thanks,
Jon

> 								Pavel
> 
> -- 
> 56:        MD5.TransformBlock( adNAME, 0, strName.IndexOf( '\0' ), adNAME, 0 );
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