A PCI-Express non-transparent bridge (NTB) is a point-to-point PCIe bus
connecting 2 systems, providing electrical isolation between the two subsystems.
A non-transparent bridge is functionally similar to a transparent bridge except
that both sides of the bridge have their own independent address domains. The
host on one side of the bridge will not have the visibility of the complete
memory or I/O space on the other side of the bridge. To communicate across the
non-transparent bridge, each NTB endpoint has one (or more) apertures exposed to
the local system. Writes to these apertures are mirrored to memory on the
remote system. Communications can also occur through the use of doorbell
registers that initiate interrupts to the alternate domain, and scratch-pad
registers accessible from both sides.
The NTB device driver is needed to configure these memory windows, doorbell, and
scratch-pad registers as well as use them in such a way as they can be turned
into a viable communication channel to the remote system. ntb_hw.[ch]
determines the usage model (NTB to NTB or NTB to Root Port) and abstracts away
the underlying hardware to provide access and a common interface to the doorbell
registers, scratch pads, and memory windows. These hardware interfaces are
exported so that other, non-mainlined kernel drivers can access these.
ntb_transport.[ch] also uses the exported interfaces in ntb_hw.[ch] to setup a
communication channel(s) and provide a reliable way of transferring data from
one side to the other, which it then exports so that "client" drivers can access
them. These client drivers are used to provide a standard kernel interface
(i.e., Ethernet device) to NTB, such that Linux can transfer data from one
system to the other in a standard way.
Signed-off-by: Jon Mason <jon.mason@intel.com>
Reviewed-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull f2fs bug fixes from Jaegeuk Kim:
"This patch-set includes two major bug fixes:
- incorrect IUsed provided by *df -i*, and
- lookup failure of parent inodes in corner cases.
[Other Bug Fixes]
- Fix error handling routines
- Trigger recovery process correctly
- Resolve build failures due to missing header files
[Etc]
- Add a MAINTAINERS entry for f2fs
- Fix and clean up variables, functions, and equations
- Avoid warnings during compilation"
* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs:
f2fs: unify string length declarations and usage
f2fs: clean up unused variables and return values
f2fs: clean up the start_bidx_of_node function
f2fs: remove unneeded variable from f2fs_sync_fs
f2fs: fix fsync_inode list addition logic and avoid invalid access to memory
f2fs: remove unneeded initialization of nr_dirty in dirty_seglist_info
f2fs: handle error from f2fs_iget_nowait
f2fs: fix equation of has_not_enough_free_secs()
f2fs: add MAINTAINERS entry
f2fs: return a default value for non-void function
f2fs: invalidate the node page if allocation is failed
f2fs: add missing #include <linux/prefetch.h>
f2fs: do f2fs_balance_fs in front of dir operations
f2fs: should recover orphan and fsync data
f2fs: fix handling errors got by f2fs_write_inode
f2fs: fix up f2fs_get_parent issue to retrieve correct parent inode number
f2fs: fix wrong calculation on f_files in statfs
f2fs: remove set_page_dirty for atomic f2fs_end_io_write
Pull late ARM cleanups for omap from Olof Johansson:
"From Tony Lindgren:
Here are few more patches to finish the omap changes for multiplatform
conversion that are not strictly fixes, but were too complex to do
with the dependencies during the merge window. Those are to move of
serial-omap.h to platform_data, and the removal of remaining
cpu_is_omap macro usage outside mach-omap2.
Then there are several trivial fixes for typos and few minimal
omap2plus_defconfig updates."
* tag 'omap-late-cleanups' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
arch/arm/mach-omap2/dpll3xxx.c: drop if around WARN_ON
OMAP2: Fix a typo - replace regist with register.
ARM/omap: use module_platform_driver macro
ARM: OMAP2+: PMU: Remove unused header
ARM: OMAP4: remove duplicated include from omap_hwmod_44xx_data.c
ARM: OMAP2+: omap2plus_defconfig: enable twl4030 SoC audio
ARM: OMAP2+: omap2plus_defconfig: Add tps65217 support
ARM: OMAP2+: enable devtmpfs and devtmpfs automount
ARM: OMAP2+: omap_twl: Change TWL4030_MODULE_PM_RECEIVER to TWL_MODULE_PM_RECEIVER
ARM: OMAP2+: Drop plat/cpu.h for omap2plus
ARM: OMAP: Split fb.c to remove last remaining cpu_is_omap usage
MAINTAINERS: Add an entry for omap related .dts files
Jon Mason
Cesar Eduardo Barros
Linus Torvalds
Jaegeuk Kim
Kim, Milo
Stefan Richter
Corentin Chary