GDB can call function i386_target_description to get the right target
description rather than tdesc_i386
gdb:
2017-09-04  Yao Qi  <yao.qi@linaro.org>
	* amd64-fbsd-nat.c (amd64fbsd_read_description): Call
	i386_target_description.
	* i386-fbsd-nat.c (i386fbsd_read_description): Call
	i386_target_description.
	* i386-tdep.c (i386_gdbarch_init): Likewise.
+2017-09-04  Yao Qi  <yao.qi@linaro.org>
+
+       * amd64-fbsd-nat.c (amd64fbsd_read_description): Call
+       i386_target_description.
+       * i386-fbsd-nat.c (i386fbsd_read_description): Call
+       i386_target_description.
+       * i386-tdep.c (i386_gdbarch_init): Likewise.
+
 2017-09-04  Yao Qi  <yao.qi@linaro.org>
 
        * amd64-darwin-tdep.c: Include "x86-xstate.h".
 
   if (is64)
     return amd64_target_description (X86_XSTATE_SSE_MASK);
   else
-    return tdesc_i386;
+    return i386_target_description (X86_XSTATE_SSE_MASK);
 }
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */
 
       xsave_probed = 1;
     }
 
-  if (x86bsd_xsave_len != 0)
-    {
-      return i386_target_description (xcr0);
-    }
-  else
-    return tdesc_i386;
+  if (x86bsd_xsave_len == 0)
+    xcr0 = X86_XSTATE_SSE_MASK;
+
+  return i386_target_description (xcr0);
 }
 #endif
 
 
   /* Get the x86 target description from INFO.  */
   tdesc = info.target_desc;
   if (! tdesc_has_registers (tdesc))
-    tdesc = tdesc_i386;
+    tdesc = i386_target_description (X86_XSTATE_SSE_MASK);
   tdep->tdesc = tdesc;
 
   tdep->num_core_regs = I386_NUM_GREGS + I387_NUM_REGS;