Greg Troxel a écrit :
The kernel doesn't save any of these registers on entry into the kernel (via an interrupt or system call) and doesn't restore them on exit. It also doesn't save and restore them on internal scheduling. If you compile the kernel with MMX or SSE<n> enabled the kernel will sooner or later globber some state and you get a panic.
Since eons I've had "-msse2 -mfpmath=sse -march=pentium4" in my /etc/mk.conf, resulting in my i386 kernel being built with those options. I've never seen a crash likely caused by these superfluous flags. I'm dubious if, anyhow, SIMD integer operations could be of a significant help in kernel operations.
Vincent