Messages in this thread | | | Subject | RE: [PATCH 2/4 v2] PCI: support ARI capability | Date | Wed, 10 Sep 2008 15:48:04 +0800 | From | "Zhao, Yu" <> |
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On Monday, September 01, 2008 11:50 PM, Roland Dreier wrote: >To: Alex Chiang >Cc: Zhao, Yu; Jesse Barnes; linux-pci@vger.kernel.org; Randy Dunlap; Greg KH; >Grant Grundler; Matthew Wilcox; linux-kernel@vger.kernel.org; >kvm@vger.kernel.org; virtualization@lists.linux-foundation.org; >xen-devel@lists.xensource.com >Subject: Re: [PATCH 2/4 v2] PCI: support ARI capability > > > > +config PCI_ARI > > > + bool "PCI ARI support" > > > + depends on PCI > > > + default n > > > + help > > > + This enables PCI Alternative Routing-ID Interpretation. > > > > This Kconfig help text is a little weak. Why not include the text > > you've already written here: > > > > Support Alternative Routing-ID Interpretation (ARI), which > > increases the number of functions that can be supported by a PCIe > > endpoint. ARI is required by SR-IOV. > >I agree with this improvement to the help text. But a further question >is whether ARI even merits its own user-visible config option. Is it >worth having yet another choice for users? When would someone want ARI >but not SR-IOV?
ARI is an independent PCI Express extended capability. Multi-function devices supporting this capability may use it to track dependency between different functions and assign function group numbers to these functions.
Another reason to keep this separated with SR-IOV is that after ARI is enabled, PCI Express Endpoint may have non-zero slot number (device number), which is different from traditional PCI Express Endpoint.
Thanks.
> > - R.
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