diff options
Diffstat (limited to 'Documentation/userspace-api')
| -rw-r--r-- | Documentation/userspace-api/netlink/specs.rst | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/Documentation/userspace-api/netlink/specs.rst b/Documentation/userspace-api/netlink/specs.rst index 40dd7442d2c3..c1b951649113 100644 --- a/Documentation/userspace-api/netlink/specs.rst +++ b/Documentation/userspace-api/netlink/specs.rst @@ -403,10 +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 @@ -416,6 +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 |