15254 %ymm registers not restored after signal handler
15367 x86 getfpregs() summons corrupting %xmm ghosts
15333 want x86 /proc xregs support (libc_db, libproc, mdb, etc.)
15336 want libc functions for extended ucontext_t
15334 want ps_lwphandle-specific reg routines
15328 FPU_CW_INIT mistreats reserved bit
15335 i86pc fpu_subr.c isn't really platform-specific
15332 setcontext(2) isn't actually noreturn
15331 need <sys/stdalign.h>
Change-Id: I7060aa86042dfb989f77fc3323c065ea2eafa9ad
Conflicts:
    usr/src/uts/common/fs/proc/prcontrol.c
    usr/src/uts/intel/os/archdep.c
    usr/src/uts/intel/sys/ucontext.h
    usr/src/uts/intel/syscall/getcontext.c

@@ -39,14 +39,12 @@
 
 #ifndef _ASM
 typedef struct fpu_ctx {
         kfpu_t          fpu_regs;       /* kernel save area for FPU */
         uint64_t        fpu_xsave_mask; /* xsave mask for FPU/SSE/AVX */
-#if defined(__i386)
-        uint64_t        fpu_padding;    /* fix 32bit libmicro regression */
-#endif
         uint_t          fpu_flags;      /* FPU state flags */
+        void            *fpu_signal;    /* copyin area for signal handling */
 } fpu_ctx_t;
 
 typedef struct pcb {
         fpu_ctx_t       pcb_fpu;        /* fpu state */
         uint_t          pcb_flags;      /* state flags; cleared on fork */