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.
Thanks,
Dongdong
Logan
.
