Bug 195447

Summary: Limit PCI DMA alias search
Product: Drivers Reporter: Bjorn Helgaas (bjorn)
Component: PCIAssignee: drivers_pci (drivers_pci)
Status: NEW ---    
Severity: normal    
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: v4.10 Subsystem:
Regression: No Bisected commit-id:
Attachments: lspci -tvn output
lspci -vv output

Description Bjorn Helgaas 2017-04-17 18:21:48 UTC 
pci_for_each_dma_alias() normally iterates all the way up to the root of a PCI hierarchy.  But on some systems the IOMMU is attached below the root, and DMA aliases generated above the IOMMU are useless.

Jayachandran C <jnair@caviumnetworks.com> has proposed patches to limit the DMA alias search on ThunderX2.  These are planned for v4.12.

The purpose of this bugzilla is only to archive lspci output showing the unusual topology of ThunderX2.
Comment 1 Bjorn Helgaas 2017-04-17 18:22:38 UTC 
Created attachment 255905 [details]
lspci -tvn output
Comment 2 Bjorn Helgaas 2017-04-17 18:24:09 UTC 
Created attachment 255907 [details]
lspci -vv output