x86/cpufeature: Carve out X86_FEATURE_*

[mirror_ubuntu-artful-kernel.git] / Documentation / kernel-parameters.txt

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index cfb2c0f1a4a89237ce131999d7b1cc03aff178b4..c0c62532150d22b5004fc5eaf7b5797f04a5bfdd 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -666,7 +666,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 
        clearcpuid=BITNUM [X86]
                        Disable CPUID feature X for the kernel. See
-                       arch/x86/include/asm/cpufeature.h for the valid bit
+                       arch/x86/include/asm/cpufeatures.h for the valid bit
                        numbers. Note the Linux specific bits are not necessarily
                        stable over kernel options, but the vendor specific
                        ones should be.
@@ -1454,6 +1454,41 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                        In such case C2/C3 won't be used again.
                        idle=nomwait: Disable mwait for CPU C-states
 
+       ieee754=        [MIPS] Select IEEE Std 754 conformance mode
+                       Format: { strict | legacy | 2008 | relaxed }
+                       Default: strict
+
+                       Choose which programs will be accepted for execution
+                       based on the IEEE 754 NaN encoding(s) supported by
+                       the FPU and the NaN encoding requested with the value
+                       of an ELF file header flag individually set by each
+                       binary.  Hardware implementations are permitted to
+                       support either or both of the legacy and the 2008 NaN
+                       encoding mode.
+
+                       Available settings are as follows:
+                       strict  accept binaries that request a NaN encoding
+                               supported by the FPU
+                       legacy  only accept legacy-NaN binaries, if supported
+                               by the FPU
+                       2008    only accept 2008-NaN binaries, if supported
+                               by the FPU
+                       relaxed accept any binaries regardless of whether
+                               supported by the FPU
+
+                       The FPU emulator is always able to support both NaN
+                       encodings, so if no FPU hardware is present or it has
+                       been disabled with 'nofpu', then the settings of
+                       'legacy' and '2008' strap the emulator accordingly,
+                       'relaxed' straps the emulator for both legacy-NaN and
+                       2008-NaN, whereas 'strict' enables legacy-NaN only on
+                       legacy processors and both NaN encodings on MIPS32 or
+                       MIPS64 CPUs.
+
+                       The setting for ABS.fmt/NEG.fmt instruction execution
+                       mode generally follows that for the NaN encoding,
+                       except where unsupported by hardware.
+
        ignore_loglevel [KNL]
                        Ignore loglevel setting - this will print /all/
                        kernel messages to the console. Useful for debugging.