+
+/* Note: the Darwin versions of arch_os_thread_init found in
+ * x86-darwin-os.c
+*/
+#if !defined(LISP_FEATURE_DARWIN)
+
+#ifdef LISP_FEATURE_SB_THREAD
+
+void set_data_desc_size(struct segment_descriptor* desc, unsigned long size)
+{
+ desc->sd_lolimit = (size - 1) & 0xffff;
+ desc->sd_hilimit = ((size - 1) >> 16) &0xf;
+}
+
+void set_data_desc_addr(struct segment_descriptor* desc, void* addr)
+{
+ desc->sd_lobase = (unsigned int)addr & 0xffffff;
+ desc->sd_hibase = ((unsigned int)addr & 0xff000000) >> 24;
+}
+
+#endif
+
+int arch_os_thread_init(struct thread *thread) {
+
+#ifdef LISP_FEATURE_SB_THREAD
+ int n;
+ int sel;
+
+ struct segment_descriptor ldt_entry = { 0, 0, SDT_MEMRW, SEL_UPL, 1,
+ 0, 0, 1, 0, 0 };
+
+ set_data_desc_addr(&ldt_entry, thread);
+ set_data_desc_size(&ldt_entry, dynamic_values_bytes);
+
+ n = i386_set_ldt(LDT_AUTO_ALLOC, (union descriptor*) &ldt_entry, 1);
+ if (n < 0) {
+ perror("i386_set_ldt");
+ lose("unexpected i386_set_ldt(..) failure\n");
+ }
+ FSHOW_SIGNAL((stderr, "/ TLS: Allocated LDT %x\n", n));
+ sel = LSEL(n, SEL_UPL);
+ load_fs(sel);
+
+ thread->tls_cookie=n;
+#ifdef LISP_FEATURE_GCC_TLS
+ current_thread = thread;
+#else
+ pthread_setspecific(specials,thread);
+#endif
+#endif
+
+#ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
+ stack_t sigstack;
+
+ /* Signal handlers are run on the control stack, so if it is exhausted
+ * we had better use an alternate stack for whatever signal tells us
+ * we've exhausted it */
+ sigstack.ss_sp=((void *) thread)+dynamic_values_bytes;
+ sigstack.ss_flags=0;
+ sigstack.ss_size = 32*SIGSTKSZ;
+ sigaltstack(&sigstack,0);
+#endif
+
+ return 1; /* success */
+}
+
+int arch_os_thread_cleanup(struct thread *thread) {
+
+#if defined(LISP_FEATURE_SB_THREAD)
+ int n = thread->tls_cookie;
+
+ /* Set the %%fs register back to 0 and free the ldt by setting it
+ * to NULL.
+ */
+ FSHOW_SIGNAL((stderr, "/ TLS: Freeing LDT %x\n", n));
+
+ __asm__ __volatile__ ("mov %0, %%fs" : : "r"(0));
+ i386_set_ldt(n, NULL, 1);
+#endif
+
+ return 1; /* success */
+}
+
+#endif /* !LISP_FEATURE_DARWIN */
+
+#if defined(LISP_FEATURE_FREEBSD)
+#if defined(LISP_FEATURE_RESTORE_TLS_SEGMENT_REGISTER_FROM_CONTEXT)
+void
+os_restore_tls_segment_register(os_context_t *context)
+{
+ load_fs(context->uc_mcontext.mc_fs);
+}
+#endif
+
+void
+os_restore_fp_control(os_context_t *context)
+{
+ /* FPU state is saved per context on post-KSE systems.
+ * On earlier systems, it is shared in a whole process.
+ */
+#if defined(__FreeBSD_version) && __FreeBSD_version >= 500040
+ struct envxmm *ex = (struct envxmm *)(context->uc_mcontext.mc_fpstate);
+ __asm__ __volatile__ ("fldcw %0" : : "m" (ex->en_cw));
+#endif
+#if defined(LISP_FEATURE_RESTORE_TLS_SEGMENT_REGISTER_FROM_CONTEXT)
+ /* Calling this function here may not be good idea. Or rename
+ * function name os_restore_fp_control to os_restore_context or
+ * so, to match the behavior? */
+ os_restore_tls_segment_register(context);
+#endif
+}
+#endif