Bug 195447 - Limit PCI DMA alias search
Summary: Limit PCI DMA alias search
Status: NEW
Alias: None
Product: Drivers
Classification: Unclassified
Component: PCI (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: drivers_pci@kernel-bugs.osdl.org
Depends on:
Reported: 2017-04-17 18:21 UTC by Bjorn Helgaas
Modified: 2017-04-17 18:24 UTC (History)
0 users

See Also:
Kernel Version: v4.10
Tree: Mainline
Regression: No

lspci -tvn output (2.04 KB, text/plain)
2017-04-17 18:22 UTC, Bjorn Helgaas
lspci -vv output (149.97 KB, text/plain)
2017-04-17 18:24 UTC, Bjorn Helgaas

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

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