There is a Xeon hardware errata related to writes to SDOORBELL or B2BDOORBELL
in conjunction with inbound access to NTB MMIO Space, which may hang the
system. To workaround this issue, use one of the memory windows to access the
interrupt and scratch pad registers on the remote system. This bypasses the
issue, but removes one of the memory windows from use by the transport. This
reduction of MWs necessitates adding some logic to determine the number of
available MWs.
Since some NTB usage methodologies may have unidirectional traffic, the ability
to disable the workaround via modparm has been added.
See BF113 in
http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/xeon-c5500-c3500-spec-update.pdf
See BT119 in
http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/xeon-e5-family-spec-update.pdf
Authored by: Jon Mason
Obtained from: Linux
Sponsored by: EMC / Isilon Storage Division
Due to ambiguous documentation, the USD/DSD identification is backward
when compared to the setting in BIOS. Correct the bits to match the
BIOS setting.
Authored by: Jon Mason
Obtained from: Linux
Sponsored by: EMC / Isilon Storage Division
The NTB Xeon hardware has 16 scratch pad registers and 16 back-to-back
scratch pad registers. Correct the #define to represent this and update
the variable names to reflect their usage.
Authored by: Jon Mason
Obtained from: Linux
Sponsored by: EMC / Isilon Storage Division
years for head. However, it is continuously misused as the mpsafe argument
for callout_init(9). Deprecate the flag and clean up callout_init() calls
to make them more consistent.
Differential Revision: https://reviews.freebsd.org/D2613
Reviewed by: jhb
MFC after: 2 weeks
The NTB allows you to connect two systems with this device using a PCI-e
link. The driver is made of two modules:
- ntb_hw which is a basic hardware abstraction layer for the device.
- if_ntb which implements the ntb network device and the communication
protocol.
The driver is limited at the moment to CPU memcpy instead of using DMA, and
only Back-to-Back mode is supported. Also the network device isn't full
featured yet. These changes will be coming soon. The DMA change will also
bring in the ioat driver from the project branch it is on now.
This is an initial port of the GPL/BSD Linux driver contributed by Jon Mason
from Intel. Any bugs are my contributions.
Sponsored by: Intel
Reviewed by: jimharris, joel (man page only)
Approved by: jimharris (mentor)
