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### 8.1 gnu Object Attributes

The `.gnu_attribute` directive records an object attribute with vendor gnu.

Except for Tag_compatibility, which has both an integer and a string for its value, gnu attributes have a string value if the tag number is odd and an integer value if the tag number is even. The second bit (tag`& 2` is set for architecture-independent attributes and clear for architecture-dependent ones.

#### 8.1.1 Common gnu attributes

These attributes are valid on all architectures.

Tag_compatibility (32)
  The compatibility attribute takes an integer flag value and a vendor name. If the flag value is 0, the file is compatible with other toolchains. If it is 1, then the file is only compatible with the named toolchain. If it is greater than 1, the file can only be processed by other toolchains under some private arrangement indicated by the flag value and the vendor name.

#### 8.1.2 MIPS Attributes

Tag_GNU_MIPS_ABI_FP (4)
  The floating-point ABI used by this object file. The value will be:
  - 0 for files not affected by the floating-point ABI.
  - 1 for files using the hardware floating-point with a standard double-precision FPU.
  - 2 for files using the hardware floating-point ABI with a single-precision FPU.
  - 3 for files using the software floating-point ABI.
  - 4 for files using the hardware floating-point ABI with 64-bit wide double-precision floating-point registers and 32-bit wide general purpose registers.

#### 8.1.3 PowerPC Attributes

Tag_GNU_Power_ABI_FP (4)
  The floating-point ABI used by this object file. The value will be:
  - 0 for files not affected by the floating-point ABI.
  - 1 for files using double-precision hardware floating-point ABI.
  - 2 for files using the software floating-point ABI.
  - 3 for files using single-precision hardware floating-point ABI.
Tag_GNU_Power_ABI_Vector (8)
  The vector ABI used by this object file. The value will be:
  - 0 for files not affected by the vector ABI.
  - 1 for files using general purpose registers to pass vectors.
  - 2 for files using AltiVec registers to pass vectors.
  - 3 for files using SPE registers to pass vectors.