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

*** 8,55 ****
   * source.  A copy of the CDDL is also available via the Internet at
   * http://www.illumos.org/license/CDDL.
   */
  
  /*
!  * Copyright 2016 Joyent, Inc.
!  * Copyright 2022 Oxide Computer Company
   */
  
  #ifndef _STDALIGN_H
  #define _STDALIGN_H
  
! /*
!  * ISO/IEC C11 stdalign.h. This header is meant to provide definitions for the
!  * alignas and alignof 'keywords' into the underlying compiler-understood value.
!  * In addition, there are two macros that are meant to define that this process
!  * has happened. C++11 added alignas/alignof as keywords and including this
!  * header is meant to cause us to still have the _is_defined macros, but not
!  * define this overall.
!  *
!  * Unlike other cases we don't use any symbol guards here (other than C++) and
!  * just allow the implementation to either have _Alignas and _Alignof or not
!  * have it and lead to a compiler error for the user. The main justification of
!  * this is that this header is only defined in C11 (and newer). It's not defined
!  * in other standards and just as if you include a non-standard header, in this
!  * case we don't try to stop that (same as if you included something like
!  * libdevinfo.h).
!  */
  
- #ifdef __cplusplus
- extern "C" {
- #endif
- 
- #ifndef __cplusplus
- 
- #define alignas _Alignas
- #define alignof _Alignof
- 
- #endif  /* !__cplusplus */
- 
- #define __alignas_is_defined    1
- #define __alignof_is_defined    1
- 
- #ifdef __cplusplus
- }
- #endif
- 
  #endif /* _STDALIGN_H */
--- 8,21 ----
   * source.  A copy of the CDDL is also available via the Internet at
   * http://www.illumos.org/license/CDDL.
   */
  
  /*
!  * Copyright 2023 Oxide Computer Company
   */
  
  #ifndef _STDALIGN_H
  #define _STDALIGN_H
  
! #include <sys/stdalign.h>
  
  #endif /* _STDALIGN_H */