On 2021-08-05 7:14 a.m., Dongdong Liu wrote: > On 2021/8/4 23:51, Logan Gunthorpe wrote: >> >> >> >> On 2021-08-04 7:47 a.m., Dongdong Liu wrote: >>> PCIe spec 5.0 r1.0 section 2.2.6.2 says that if an Endpoint supports >>> sending Requests to other Endpoints (as opposed to host memory), the >>> Endpoint must not send 10-Bit Tag Requests to another given Endpoint >>> unless an implementation-specific mechanism determines that the Endpoint >>> supports 10-Bit Tag Completer capability. Add a 10bit_tag sysfs file, >>> write 0 to disable 10-Bit Tag Requester when the driver does not bind >>> the device if the peer device does not support the 10-Bit Tag Completer. >>> This will make P2P traffic safe. the 10bit_tag file content indicate >>> current 10-Bit Tag Requester Enable status. >> >> Can we not have both the sysfs file and the command line parameter? If >> the user wants to disable it always for a specific device this sysfs >> parameter is fairly awkward. A script at boot to unbind the driver, set >> the sysfs file and rebind the driver is not trivial and the command line >> parameter offers additional options for users. > Does the command line parameter as "[PATCH V6 7/8] PCI: Add > "pci=disable_10bit_tag=" parameter for peer-to-peer support" does? > > Do we also need such command line if we already had sysfs file? > I think we may not need. In my opinion, for reasons stated above, the command line parameter is way more convenient. Logan
