€•9;      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ)/translations/zh_CN/infiniband/user_verbs”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/zh_TW/infiniband/user_verbs”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/it_IT/infiniband/user_verbs”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/ja_JP/infiniband/user_verbs”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/ko_KR/infiniband/user_verbs”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/sp_SP/infiniband/user_verbs”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒUserspace verbs access”h]”hŒUserspace verbs access”…””}”(hh¨hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hh£hžhhŸŒC/var/lib/git/docbuild/linux/Documentation/infiniband/user_verbs.rst”h KubhŒblock_quote”“”)”}”(hXy  The ib_uverbs module, built by enabling CONFIG_INFINIBAND_USER_VERBS,
enables direct userspace access to IB hardware via "verbs," as
described in chapter 11 of the InfiniBand Architecture Specification.

To use the verbs, the libibverbs library, available from
https://github.com/linux-rdma/rdma-core, is required. libibverbs contains a
device-independent API for using the ib_uverbs interface.
libibverbs also requires appropriate device-dependent kernel and
userspace driver for your InfiniBand hardware.  For example, to use
a Mellanox HCA, you will need the ib_mthca kernel module and the
libmthca userspace driver be installed.
”h]”(hŒ	paragraph”“”)”}”(hŒÊThe ib_uverbs module, built by enabling CONFIG_INFINIBAND_USER_VERBS,
enables direct userspace access to IB hardware via "verbs," as
described in chapter 11 of the InfiniBand Architecture Specification.”h]”hŒÎThe ib_uverbs module, built by enabling CONFIG_INFINIBAND_USER_VERBS,
enables direct userspace access to IB hardware via â€œverbs,â€ as
described in chapter 11 of the InfiniBand Architecture Specification.”…””}”(hh¿hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h½hŸh¶h Khh¹ubh¾)”}”(hX¬  To use the verbs, the libibverbs library, available from
https://github.com/linux-rdma/rdma-core, is required. libibverbs contains a
device-independent API for using the ib_uverbs interface.
libibverbs also requires appropriate device-dependent kernel and
userspace driver for your InfiniBand hardware.  For example, to use
a Mellanox HCA, you will need the ib_mthca kernel module and the
libmthca userspace driver be installed.”h]”(hŒ9To use the verbs, the libibverbs library, available from
”…””}”(hhÍhžhhŸNh NubhŒ	reference”“”)”}”(hŒ'https://github.com/linux-rdma/rdma-core”h]”hŒ'https://github.com/linux-rdma/rdma-core”…””}”(hh×hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”hÙuh1hÕhhÍubhXL  , is required. libibverbs contains a
device-independent API for using the ib_uverbs interface.
libibverbs also requires appropriate device-dependent kernel and
userspace driver for your InfiniBand hardware.  For example, to use
a Mellanox HCA, you will need the ib_mthca kernel module and the
libmthca userspace driver be installed.”…””}”(hhÍhžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h½hŸh¶h K	hh¹ubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¢)”}”(hhh]”(h§)”}”(hŒUser-kernel communication”h]”hŒUser-kernel communication”…””}”(hhùhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hhöhžhhŸh¶h Kubh¸)”}”(hX‹  Userspace communicates with the kernel for slow path, resource
management operations via the /dev/infiniband/uverbsN character
devices.  Fast path operations are typically performed by writing
directly to hardware registers mmap()ed into userspace, with no
system call or context switch into the kernel.

Commands are sent to the kernel via write()s on these device files.
The ABI is defined in drivers/infiniband/include/ib_user_verbs.h.
The structs for commands that require a response from the kernel
contain a 64-bit field used to pass a pointer to an output buffer.
Status is returned to userspace as the return value of the write()
system call.
”h]”(h¾)”}”(hX/  Userspace communicates with the kernel for slow path, resource
management operations via the /dev/infiniband/uverbsN character
devices.  Fast path operations are typically performed by writing
directly to hardware registers mmap()ed into userspace, with no
system call or context switch into the kernel.”h]”hX/  Userspace communicates with the kernel for slow path, resource
management operations via the /dev/infiniband/uverbsN character
devices.  Fast path operations are typically performed by writing
directly to hardware registers mmap()ed into userspace, with no
system call or context switch into the kernel.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h½hŸh¶h Khj  ubh¾)”}”(hXY  Commands are sent to the kernel via write()s on these device files.
The ABI is defined in drivers/infiniband/include/ib_user_verbs.h.
The structs for commands that require a response from the kernel
contain a 64-bit field used to pass a pointer to an output buffer.
Status is returned to userspace as the return value of the write()
system call.”h]”hXY  Commands are sent to the kernel via write()s on these device files.
The ABI is defined in drivers/infiniband/include/ib_user_verbs.h.
The structs for commands that require a response from the kernel
contain a 64-bit field used to pass a pointer to an output buffer.
Status is returned to userspace as the return value of the write()
system call.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h½hŸh¶h Khj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khhöhžhubeh}”(h]”Œuser-kernel-communication”ah ]”h"]”Œuser-kernel communication”ah$]”h&]”uh1h¡hh£hžhhŸh¶h Kubh¢)”}”(hhh]”(h§)”}”(hŒResource management”h]”hŒResource management”…””}”(hj8  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hj5  hžhhŸh¶h K"ubh¸)”}”(hX;  Since creation and destruction of all IB resources is done by
commands passed through a file descriptor, the kernel can keep track
of which resources are attached to a given userspace context.  The
ib_uverbs module maintains idr tables that are used to translate
between kernel pointers and opaque userspace handles, so that kernel
pointers are never exposed to userspace and userspace cannot trick
the kernel into following a bogus pointer.

This also allows the kernel to clean up when a process exits and
prevent one process from touching another process's resources.
”h]”(h¾)”}”(hX¹  Since creation and destruction of all IB resources is done by
commands passed through a file descriptor, the kernel can keep track
of which resources are attached to a given userspace context.  The
ib_uverbs module maintains idr tables that are used to translate
between kernel pointers and opaque userspace handles, so that kernel
pointers are never exposed to userspace and userspace cannot trick
the kernel into following a bogus pointer.”h]”hX¹  Since creation and destruction of all IB resources is done by
commands passed through a file descriptor, the kernel can keep track
of which resources are attached to a given userspace context.  The
ib_uverbs module maintains idr tables that are used to translate
between kernel pointers and opaque userspace handles, so that kernel
pointers are never exposed to userspace and userspace cannot trick
the kernel into following a bogus pointer.”…””}”(hjJ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h½hŸh¶h K$hjF  ubh¾)”}”(hŒThis also allows the kernel to clean up when a process exits and
prevent one process from touching another process's resources.”h]”hŒThis also allows the kernel to clean up when a process exits and
prevent one process from touching another processâ€™s resources.”…””}”(hjX  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h½hŸh¶h K,hjF  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K$hj5  hžhubeh}”(h]”Œresource-management”ah ]”h"]”Œresource management”ah$]”h&]”uh1h¡hh£hžhhŸh¶h K"ubh¢)”}”(hhh]”(h§)”}”(hŒMemory pinning”h]”hŒMemory pinning”…””}”(hjw  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hjt  hžhhŸh¶h K0ubh¸)”}”(hX7  Direct userspace I/O requires that memory regions that are potential
I/O targets be kept resident at the same physical address.  The
ib_uverbs module manages pinning and unpinning memory regions via
get_user_pages() and put_page() calls.  It also accounts for the
amount of memory pinned in the process's pinned_vm, and checks that
unprivileged processes do not exceed their RLIMIT_MEMLOCK limit.

Pages that are pinned multiple times are counted each time they are
pinned, so the value of pinned_vm may be an overestimate of the
number of pages pinned by a process.
”h]”(h¾)”}”(hXŒ  Direct userspace I/O requires that memory regions that are potential
I/O targets be kept resident at the same physical address.  The
ib_uverbs module manages pinning and unpinning memory regions via
get_user_pages() and put_page() calls.  It also accounts for the
amount of memory pinned in the process's pinned_vm, and checks that
unprivileged processes do not exceed their RLIMIT_MEMLOCK limit.”h]”hXŽ  Direct userspace I/O requires that memory regions that are potential
I/O targets be kept resident at the same physical address.  The
ib_uverbs module manages pinning and unpinning memory regions via
get_user_pages() and put_page() calls.  It also accounts for the
amount of memory pinned in the processâ€™s pinned_vm, and checks that
unprivileged processes do not exceed their RLIMIT_MEMLOCK limit.”…””}”(hj‰  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h½hŸh¶h K2hj…  ubh¾)”}”(hŒ¨Pages that are pinned multiple times are counted each time they are
pinned, so the value of pinned_vm may be an overestimate of the
number of pages pinned by a process.”h]”hŒ¨Pages that are pinned multiple times are counted each time they are
pinned, so the value of pinned_vm may be an overestimate of the
number of pages pinned by a process.”…””}”(hj—  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h½hŸh¶h K9hj…  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K2hjt  hžhubeh}”(h]”Œmemory-pinning”ah ]”h"]”Œmemory pinning”ah$]”h&]”uh1h¡hh£hžhhŸh¶h K0ubh¢)”}”(hhh]”(h§)”}”(hŒ
/dev files”h]”hŒ
/dev files”…””}”(hj¶  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hj³  hžhhŸh¶h K>ubh¸)”}”(hX  To create the appropriate character device files automatically with
udev, a rule like::

  KERNEL=="uverbs*", NAME="infiniband/%k"

can be used.  This will create device nodes named::

  /dev/infiniband/uverbs0

and so on.  Since the InfiniBand userspace verbs should be safe for
use by non-privileged processes, it may be useful to add an
appropriate MODE or GROUP to the udev rule.”h]”(h¾)”}”(hŒWTo create the appropriate character device files automatically with
udev, a rule like::”h]”hŒVTo create the appropriate character device files automatically with
udev, a rule like:”…””}”(hjÈ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h½hŸh¶h K@hjÄ  ubhŒliteral_block”“”)”}”(hŒ'KERNEL=="uverbs*", NAME="infiniband/%k"”h]”hŒ'KERNEL=="uverbs*", NAME="infiniband/%k"”…””}”hjØ  sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1jÖ  hŸh¶h KChjÄ  ubh¾)”}”(hŒ3can be used.  This will create device nodes named::”h]”hŒ2can be used.  This will create device nodes named:”…””}”(hjè  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h½hŸh¶h KEhjÄ  ubj×  )”}”(hŒ/dev/infiniband/uverbs0”h]”hŒ/dev/infiniband/uverbs0”…””}”hjö  sbah}”(h]”h ]”h"]”h$]”h&]”jæ  jç  uh1jÖ  hŸh¶h KGhjÄ  ubh¾)”}”(hŒ«and so on.  Since the InfiniBand userspace verbs should be safe for
use by non-privileged processes, it may be useful to add an
appropriate MODE or GROUP to the udev rule.”h]”hŒ«and so on.  Since the InfiniBand userspace verbs should be safe for
use by non-privileged processes, it may be useful to add an
appropriate MODE or GROUP to the udev rule.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h½hŸh¶h KIhjÄ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K@hj³  hžhubeh}”(h]”Œ	dev-files”ah ]”h"]”Œ
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decoration”Nhžhub.