+/* Get Linux/x86 target description from running target. */
+
+static const struct target_desc *
+i386_linux_read_description (struct target_ops *ops)
+{
+ int tid;
+ static uint64_t xcr0;
+
+ /* GNU/Linux LWP ID's are process ID's. */
+ tid = TIDGET (inferior_ptid);
+ if (tid == 0)
+ tid = PIDGET (inferior_ptid); /* Not a threaded program. */
+
+#ifdef HAVE_PTRACE_GETFPXREGS
+ if (have_ptrace_getfpxregs == -1)
+ {
+ elf_fpxregset_t fpxregs;
+
+ if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
+ {
+ have_ptrace_getfpxregs = 0;
+ have_ptrace_getregset = 0;
+ return tdesc_i386_mmx_linux;
+ }
+ }
+#endif
+
+ if (have_ptrace_getregset == -1)
+ {
+ uint64_t xstateregs[(I386_XSTATE_SSE_SIZE / sizeof (uint64_t))];
+ struct iovec iov;
+
+ iov.iov_base = xstateregs;
+ iov.iov_len = sizeof (xstateregs);
+
+ /* Check if PTRACE_GETREGSET works. */
+ if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
+ &iov) < 0)
+ have_ptrace_getregset = 0;
+ else
+ {
+ have_ptrace_getregset = 1;
+
+ /* Get XCR0 from XSAVE extended state. */
+ xcr0 = xstateregs[(I386_LINUX_XSAVE_XCR0_OFFSET
+ / sizeof (long long))];
+ }
+ }
+
+ /* Check the native XCR0 only if PTRACE_GETREGSET is available. */
+ if (have_ptrace_getregset
+ && (xcr0 & I386_XSTATE_AVX_MASK) == I386_XSTATE_AVX_MASK)
+ return tdesc_i386_avx_linux;
+ else
+ return tdesc_i386_linux;
+}
+
+/* Enable branch tracing. */
+
+static struct btrace_target_info *
+i386_linux_enable_btrace (ptid_t ptid)
+{
+ struct btrace_target_info *tinfo;
+ struct gdbarch *gdbarch;
+
+ errno = 0;
+ tinfo = linux_enable_btrace (ptid);
+
+ if (tinfo == NULL)
+ error (_("Could not enable branch tracing for %s: %s."),
+ target_pid_to_str (ptid), safe_strerror (errno));
+
+ /* Fill in the size of a pointer in bits. */
+ gdbarch = target_thread_architecture (ptid);
+ tinfo->ptr_bits = gdbarch_ptr_bit (gdbarch);
+
+ return tinfo;
+}
+
+/* Disable branch tracing. */
+
+static void
+i386_linux_disable_btrace (struct btrace_target_info *tinfo)
+{
+ int errcode = linux_disable_btrace (tinfo);
+
+ if (errcode != 0)
+ error (_("Could not disable branch tracing: %s."), safe_strerror (errcode));
+}
+
+/* Teardown branch tracing. */
+
+static void
+i386_linux_teardown_btrace (struct btrace_target_info *tinfo)
+{
+ /* Ignore errors. */
+ linux_disable_btrace (tinfo);
+}
+
+/* -Wmissing-prototypes */
+extern initialize_file_ftype _initialize_i386_linux_nat;
+