Bring back LX zones.

*** 159,169 ****
  
  /*
   * The brand infrastructure interposes on two handlers, and we use one as a
   * NULL signpost.
   */
! static struct interposing_handler brand_tbl[2];
  
  /*
   * software prototypes for default local descriptor table
   */
  
--- 159,169 ----
  
  /*
   * The brand infrastructure interposes on two handlers, and we use one as a
   * NULL signpost.
   */
! static struct interposing_handler brand_tbl[3];
  
  /*
   * software prototypes for default local descriptor table
   */
  
*** 975,984 ****
--- 975,990 ----
              TRP_KPL, 0);
          set_gatesegd(&idt[T_MCE], &mcetrap, KCS_SEL, SDT_SYSIGT, TRP_KPL, 0);
          set_gatesegd(&idt[T_SIMDFPE], &xmtrap, KCS_SEL, SDT_SYSIGT, TRP_KPL, 0);
  
          /*
+          * install "int80" handler at, well, 0x80.
+          */
+         set_gatesegd(&idt0[T_INT80], &sys_int80, KCS_SEL, SDT_SYSIGT, TRP_UPL,
+             0);
+ 
+         /*
           * install fast trap handler at 210.
           */
          set_gatesegd(&idt[T_FASTTRAP], &fasttrap, KCS_SEL, SDT_SYSIGT, TRP_UPL,
              0);
  
*** 999,1023 ****
           */
          set_gatesegd(&idt[T_DTRACE_RET], &dtrace_ret, KCS_SEL,
              SDT_SYSIGT, TRP_UPL, 0);
  
          /*
!          * Prepare interposing descriptor for the syscall handler
!          * and cache copy of the default descriptor.
!          */
!         brand_tbl[0].ih_inum = T_SYSCALLINT;
!         brand_tbl[0].ih_default_desc = idt0[T_SYSCALLINT];
  
  #if defined(__amd64)
!         set_gatesegd(&(brand_tbl[0].ih_interp_desc), &brand_sys_syscall_int,
              KCS_SEL, SDT_SYSIGT, TRP_UPL, 0);
  #elif defined(__i386)
!         set_gatesegd(&(brand_tbl[0].ih_interp_desc), &brand_sys_call,
              KCS_SEL, SDT_SYSIGT, TRP_UPL, 0);
  #endif  /* __i386 */
  
!         brand_tbl[1].ih_inum = 0;
  }
  
  #if defined(__xpv)
  
  static void
--- 1005,1035 ----
           */
          set_gatesegd(&idt[T_DTRACE_RET], &dtrace_ret, KCS_SEL,
              SDT_SYSIGT, TRP_UPL, 0);
  
          /*
! -        * Prepare interposing descriptors for the branded "int80"
! -        * and syscall handlers and cache copies of the default
! -        * descriptors.
!          */
!         brand_tbl[0].ih_inum = T_INT80;
!         brand_tbl[0].ih_default_desc = idt0[T_INT80];
!         set_gatesegd(&(brand_tbl[0].ih_interp_desc), &brand_sys_int80, KCS_SEL,
!             SDT_SYSIGT, TRP_UPL, 0);
! 
!         brand_tbl[1].ih_inum = T_SYSCALLINT;
!         brand_tbl[1].ih_default_desc = idt0[T_SYSCALLINT];
  
  #if defined(__amd64)
!         set_gatesegd(&(brand_tbl[1].ih_interp_desc), &brand_sys_syscall_int,
              KCS_SEL, SDT_SYSIGT, TRP_UPL, 0);
  #elif defined(__i386)
!         set_gatesegd(&(brand_tbl[1].ih_interp_desc), &brand_sys_call,
              KCS_SEL, SDT_SYSIGT, TRP_UPL, 0);
  #endif  /* __i386 */
  
!         brand_tbl[2].ih_inum = 0;
  }
  
  #if defined(__xpv)
  
  static void