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Diffstat (limited to 'Documentation/userspace-api/netlink/specs.rst')
| -rw-r--r-- | Documentation/userspace-api/netlink/specs.rst | 38 |
1 files changed, 30 insertions, 8 deletions
diff --git a/Documentation/userspace-api/netlink/specs.rst b/Documentation/userspace-api/netlink/specs.rst index 2e4acde890b7..1b50d97d8d7c 100644 --- a/Documentation/userspace-api/netlink/specs.rst +++ b/Documentation/userspace-api/netlink/specs.rst @@ -15,7 +15,7 @@ kernel headers directly. Internally kernel uses the YAML specs to generate: - the C uAPI header - - documentation of the protocol as a ReST file + - documentation of the protocol as a ReST file - see :ref:`Documentation/networking/netlink_spec/index.rst <specs>` - policy tables for input attribute validation - operation tables @@ -68,6 +68,10 @@ The following sections describe the properties of the most modern ``genetlink`` schema. See the documentation of :doc:`genetlink-c <c-code-gen>` for information on how C names are derived from name properties. +See also :ref:`Documentation/core-api/netlink.rst <kernel_netlink>` for +information on the Netlink specification properties that are only relevant to +the kernel space and not part of the user space API. + genetlink ========= @@ -82,11 +86,6 @@ name Name of the family. Name identifies the family in a unique way, since the Family IDs are allocated dynamically. -version -~~~~~~~ - -Generic Netlink family version, default is 1. - protocol ~~~~~~~~ @@ -180,6 +179,8 @@ attributes List of attributes in the set. +.. _attribute_properties: + Attribute properties -------------------- @@ -264,6 +265,13 @@ a C array of u32 values can be specified with ``type: binary`` and ``sub-type: u32``. Binary types and legacy array formats are described in more detail in :doc:`genetlink-legacy`. +display-hint +~~~~~~~~~~~~ + +Optional format indicator that is intended only for choosing the right +formatting mechanism when displaying values of this type. Currently supported +hints are ``hex``, ``mac``, ``fddi``, ``ipv4``, ``ipv6`` and ``uuid``. + operations ---------- @@ -395,10 +403,21 @@ This section describes the attribute types supported by the ``genetlink`` compatibility level. Refer to documentation of different levels for additional attribute types. -Scalar integer types +Common integer types -------------------- -Fixed-width integer types: +``sint`` and ``uint`` represent signed and unsigned 64 bit integers. +If the value can fit on 32 bits only 32 bits are carried in netlink +messages, otherwise full 64 bits are carried. Note that the payload +is only aligned to 4B, so the full 64 bit value may be unaligned! + +Common integer types should be preferred over fix-width types in majority +of cases. + +Fix-width integer types +----------------------- + +Fixed-width integer types include: ``u8``, ``u16``, ``u32``, ``u64``, ``s8``, ``s16``, ``s32``, ``s64``. Note that types smaller than 32 bit should be avoided as using them @@ -408,6 +427,9 @@ See :ref:`pad_type` for padding of 64 bit attributes. The payload of the attribute is the integer in host order unless ``byte-order`` specifies otherwise. +64 bit values are usually aligned by the kernel but it is recommended +that the user space is able to deal with unaligned values. + .. _pad_type: pad |