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diff --git a/gdb/arch/x86-linux-tdesc-features.c b/gdb/arch/x86-linux-tdesc-features.c
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+++ b/gdb/arch/x86-linux-tdesc-features.c
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+/* Target description related code for GNU/Linux x86 (i386 and x86-64).
+
+   Copyright (C) 2024 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "arch/x86-linux-tdesc-features.h"
+
+/* A structure used to describe a single xstate feature bit that might, or
+   might not, be checked for when creating a target description for one of
+   i386, amd64, or x32.
+
+   The different CPU/ABI types check for different xstate features when
+   creating a target description.
+
+   We want to cache target descriptions, and this is currently done in
+   three separate caches, one each for i386, amd64, and x32.  Additionally,
+   the caching we're discussing here is Linux only, and for Linux, the only
+   thing that has an impact on target description creation is the xcr0
+   value.
+
+   In order to ensure the cache functions correctly we need to filter out
+   only those xcr0 feature bits that are relevant, we can then cache target
+   descriptions based on the relevant feature bits.  Two xcr0 values might
+   be different, but have the same relevant feature bits.  In this case we
+   would expect the two xcr0 values to map to the same cache entry.  */
+
+struct x86_xstate_feature {
+  /* The xstate feature mask.  This is a mask against an xcr0 value.  */
+  uint64_t feature;
+
+  /* Is this feature checked when creating an i386 target description.  */
+  bool is_i386;
+
+  /* Is this feature checked when creating an amd64 target description.  */
+  bool is_amd64;
+
+  /* Is this feature checked when creating an x32 target description.  */
+  bool is_x32;
+};
+
+/* A constant table that describes all of the xstate features that are
+   checked when building a target description for i386, amd64, or x32.
+
+   If in the future, due to simplifications or refactoring, this table ever
+   ends up with 'true' for every xcr0 feature on every target type, then this
+   is an indication that this table should probably be removed, and that the
+   rest of the code in this file can be simplified.  */
+
+static constexpr x86_xstate_feature x86_linux_all_xstate_features[] = {
+  /* Feature,           i386,	amd64,	x32.  */
+  { X86_XSTATE_PKRU,	true,	true, 	true },
+  { X86_XSTATE_AVX512,	true,	true, 	true },
+  { X86_XSTATE_AVX,	true,	true, 	true },
+  { X86_XSTATE_MPX,	true,	true, 	false },
+  { X86_XSTATE_SSE,	true,	false, 	false },
+  { X86_XSTATE_X87,	true,	false, 	false }
+};
+
+/* Return a compile time constant which is a mask of all the xstate features
+   that are checked for when building an i386 target description.  */
+
+static constexpr uint64_t
+x86_linux_i386_xcr0_feature_mask_1 ()
+{
+  uint64_t mask = 0;
+
+  for (const auto &entry : x86_linux_all_xstate_features)
+    if (entry.is_i386)
+      mask |= entry.feature;
+
+  return mask;
+}
+
+/* Return a compile time constant which is a mask of all the xstate features
+   that are checked for when building an amd64 target description.  */
+
+static constexpr uint64_t
+x86_linux_amd64_xcr0_feature_mask_1 ()
+{
+  uint64_t mask = 0;
+
+  for (const auto &entry : x86_linux_all_xstate_features)
+    if (entry.is_amd64)
+      mask |= entry.feature;
+
+  return mask;
+}
+
+/* Return a compile time constant which is a mask of all the xstate features
+   that are checked for when building an x32 target description.  */
+
+static constexpr uint64_t
+x86_linux_x32_xcr0_feature_mask_1 ()
+{
+  uint64_t mask = 0;
+
+  for (const auto &entry : x86_linux_all_xstate_features)
+    if (entry.is_x32)
+      mask |= entry.feature;
+
+  return mask;
+}
+
+/* See arch/x86-linux-tdesc-features.h.  */
+
+uint64_t
+x86_linux_i386_xcr0_feature_mask ()
+{
+  return x86_linux_i386_xcr0_feature_mask_1 ();
+}
+
+/* See arch/x86-linux-tdesc-features.h.  */
+
+uint64_t
+x86_linux_amd64_xcr0_feature_mask ()
+{
+  return x86_linux_amd64_xcr0_feature_mask_1 ();
+}
+
+/* See arch/x86-linux-tdesc-features.h.  */
+
+uint64_t
+x86_linux_x32_xcr0_feature_mask ()
+{
+  return x86_linux_x32_xcr0_feature_mask_1 ();
+}
+
+#ifdef GDBSERVER
+
+/* See arch/x86-linux-tdesc-features.h.  */
+
+int
+x86_linux_xcr0_to_tdesc_idx (uint64_t xcr0)
+{
+  /* The following table shows which features are checked for when creating
+     the target descriptions (see nat/x86-linux-tdesc.c), the feature order
+     represents the bit order within the generated index number.
+
+     i386  | x87 sse mpx avx avx512 pkru
+     amd64 |         mpx avx avx512 pkru
+     i32   |             avx avx512 pkru
+
+     The features are ordered so that for each mode (i386, amd64, i32) the
+     generated index will form a continuous range.  */
+
+  int idx = 0;
+
+  for (int i = 0; i < ARRAY_SIZE (x86_linux_all_xstate_features); ++i)
+    {
+      if ((xcr0 & x86_linux_all_xstate_features[i].feature)
+	  == x86_linux_all_xstate_features[i].feature)
+	idx |= (1 << i);
+    }
+
+  return idx;
+}
+
+#endif /* GDBSERVER */
+
+#ifdef IN_PROCESS_AGENT
+
+/* Return a compile time constant which is a count of the number of xstate
+   features that are checked for when building an i386 target description.  */
+
+static constexpr int
+x86_linux_i386_tdesc_count_1 ()
+{
+  uint64_t count = 0;
+
+  for (const auto &entry : x86_linux_all_xstate_features)
+    if (entry.is_i386)
+      ++count;
+
+  gdb_assert (count > 0);
+
+  return (1 << count);
+}
+
+/* Return a compile time constant which is a count of the number of xstate
+   features that are checked for when building an amd64 target description.  */
+
+static constexpr int
+x86_linux_amd64_tdesc_count_1 ()
+{
+  uint64_t count = 0;
+
+  for (const auto &entry : x86_linux_all_xstate_features)
+    if (entry.is_amd64)
+      ++count;
+
+  gdb_assert (count > 0);
+
+  return (1 << count);
+}
+
+/* Return a compile time constant which is a count of the number of xstate
+   features that are checked for when building an x32 target description.  */
+
+static constexpr int
+x86_linux_x32_tdesc_count_1 ()
+{
+  uint64_t count = 0;
+
+  for (const auto &entry : x86_linux_all_xstate_features)
+    if (entry.is_x32)
+      ++count;
+
+  gdb_assert (count > 0);
+
+  return (1 << count);
+}
+
+/* See arch/x86-linux-tdesc-features.h.  */
+
+int
+x86_linux_amd64_tdesc_count ()
+{
+  return x86_linux_amd64_tdesc_count_1 ();
+}
+
+/* See arch/x86-linux-tdesc-features.h.  */
+
+int
+x86_linux_x32_tdesc_count ()
+{
+  return x86_linux_x32_tdesc_count_1 ();
+}
+
+/* See arch/x86-linux-tdesc-features.h.  */
+
+int
+x86_linux_i386_tdesc_count ()
+{
+  return x86_linux_i386_tdesc_count_1 ();
+}
+
+/* See arch/x86-linux-tdesc-features.h.  */
+
+uint64_t
+x86_linux_tdesc_idx_to_xcr0 (int idx)
+{
+  uint64_t xcr0 = 0;
+
+  for (int i = 0; i < ARRAY_SIZE (x86_linux_all_xstate_features); ++i)
+    {
+      if ((idx & (1 << i)) != 0)
+	xcr0 |= x86_linux_all_xstate_features[i].feature;
+    }
+
+  return xcr0;
+}
+
+#endif /* IN_PROCESS_AGENT */