Re: [PATCH v4 07/18] PCI/P2PDMA: Document the Address Type assumption
Jason Gunthorpe <[email protected]>
| Newsgroups | org.kernel.vger.linux-doc,dev.linux.lists.iommu,org.kernel.vger.linux-kernel,org.kernel.vger.linux-pci |
|---|---|
| Message-ID | <178761377055.3197084.12191528318950950293.b4-review@b4> |
> [ ... 21 lines skipped ... ] > +This evaluation covers the ACS controls that govern Requests carrying an > +Untranslated address. Unless ACS Translation Blocking is enabled, a Port > +with ACS Direct Translated P2P enabled routes a Request carrying a Translated > +address directly to the peer regardless of those controls. An ATS capable > +client may therefore reach the peer on the direct path whichever mapping the > +kernel selects. My note on the cover letter applies here.. A user of the p2p subsystem kind of has to issue untranslated strict ordered TLPs otherwise the ACS analysis is not correct. A translated address routing to the host bridge for a peer device still requires support in the host bridge to hairpin back out. So I would prefer this is clarified to that that exactly, using it with ATS translated TLPs is not defined. -- Jason