diff --git a/lib/spack/spack/bootstrap/clingo.py b/lib/spack/spack/bootstrap/clingo.py
index c55addf12f2..17a86baf39d 100644
--- a/lib/spack/spack/bootstrap/clingo.py
+++ b/lib/spack/spack/bootstrap/clingo.py
@@ -27,9 +27,9 @@
 class ClingoBootstrapConcretizer:
     def __init__(self, configuration):
         self.host_platform = spack.platforms.host()
-        self.host_os = self.host_platform.operating_system("frontend")
+        self.host_os = self.host_platform.default_operating_system()
         self.host_target = archspec.cpu.host().family
-        self.host_architecture = spack.spec.ArchSpec.frontend_arch()
+        self.host_architecture = spack.spec.ArchSpec.default_arch()
         self.host_architecture.target = str(self.host_target)
         self.host_compiler = self._valid_compiler_or_raise()
         self.host_python = self.python_external_spec()
diff --git a/lib/spack/spack/bootstrap/config.py b/lib/spack/spack/bootstrap/config.py
index a81be057563..4c0ff117664 100644
--- a/lib/spack/spack/bootstrap/config.py
+++ b/lib/spack/spack/bootstrap/config.py
@@ -141,7 +141,7 @@ def _bootstrap_config_scopes() -> Sequence["spack.config.ConfigScope"]:
 
 
 def _add_compilers_if_missing() -> None:
-    arch = spack.spec.ArchSpec.frontend_arch()
+    arch = spack.spec.ArchSpec.default_arch()
     if not spack.compilers.compilers_for_arch(arch):
         spack.compilers.find_compilers()
 
diff --git a/lib/spack/spack/build_systems/python.py b/lib/spack/spack/build_systems/python.py
index e09408fcd7f..557fca15d4b 100644
--- a/lib/spack/spack/build_systems/python.py
+++ b/lib/spack/spack/build_systems/python.py
@@ -264,16 +264,17 @@ def update_external_dependencies(self, extendee_spec=None):
                     # Ensure architecture information is present
                     if not python.architecture:
                         host_platform = spack.platforms.host()
-                        host_os = host_platform.operating_system("default_os")
-                        host_target = host_platform.target("default_target")
+                        host_os = host_platform.default_operating_system()
+                        host_target = host_platform.default_target()
                         python.architecture = spack.spec.ArchSpec(
                             (str(host_platform), str(host_os), str(host_target))
                         )
                     else:
                         if not python.architecture.platform:
                             python.architecture.platform = spack.platforms.host()
+                        platform = spack.platforms.by_name(python.architecture.platform)
                         if not python.architecture.os:
-                            python.architecture.os = "default_os"
+                            python.architecture.os = platform.default_operating_system()
                         if not python.architecture.target:
                             python.architecture.target = archspec.cpu.host().family.name
 
diff --git a/lib/spack/spack/cmd/arch.py b/lib/spack/spack/cmd/arch.py
index 683fd01450d..8f810bc9840 100644
--- a/lib/spack/spack/cmd/arch.py
+++ b/lib/spack/spack/cmd/arch.py
@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 import collections
+import warnings
 
 import archspec.cpu
 
@@ -51,10 +52,10 @@ def setup_parser(subparser):
         "-t", "--target", action="store_true", default=False, help="print only the target"
     )
     parts2.add_argument(
-        "-f", "--frontend", action="store_true", default=False, help="print frontend"
+        "-f", "--frontend", action="store_true", default=False, help="print frontend (DEPRECATED)"
     )
     parts2.add_argument(
-        "-b", "--backend", action="store_true", default=False, help="print backend"
+        "-b", "--backend", action="store_true", default=False, help="print backend (DEPRECATED)"
     )
 
 
@@ -98,15 +99,14 @@ def arch(parser, args):
         display_targets(archspec.cpu.TARGETS)
         return
 
-    os_args, target_args = "default_os", "default_target"
     if args.frontend:
-        os_args, target_args = "frontend", "frontend"
+        warnings.warn("the argument --frontend is deprecated, and will be removed in Spack v1.0")
     elif args.backend:
-        os_args, target_args = "backend", "backend"
+        warnings.warn("the argument --backend is deprecated, and will be removed in Spack v1.0")
 
     host_platform = spack.platforms.host()
-    host_os = host_platform.operating_system(os_args)
-    host_target = host_platform.target(target_args)
+    host_os = host_platform.default_operating_system()
+    host_target = host_platform.default_target()
     if args.family:
         host_target = host_target.family
     elif args.generic:
diff --git a/lib/spack/spack/cmd/debug.py b/lib/spack/spack/cmd/debug.py
index e03479955a4..f9ef00a1a7f 100644
--- a/lib/spack/spack/cmd/debug.py
+++ b/lib/spack/spack/cmd/debug.py
@@ -86,8 +86,8 @@ def create_db_tarball(args):
 
 def report(args):
     host_platform = spack.platforms.host()
-    host_os = host_platform.operating_system("frontend")
-    host_target = host_platform.target("frontend")
+    host_os = host_platform.default_operating_system()
+    host_target = host_platform.default_target()
     architecture = spack.spec.ArchSpec((str(host_platform), str(host_os), str(host_target)))
     print("* **Spack:**", spack.get_version())
     print("* **Python:**", platform.python_version())
diff --git a/lib/spack/spack/cmd/help.py b/lib/spack/spack/cmd/help.py
index 3b754cd6ef2..ace7ef224d0 100644
--- a/lib/spack/spack/cmd/help.py
+++ b/lib/spack/spack/cmd/help.py
@@ -54,10 +54,6 @@
       @m{target=target}                 specific <target> processor
       @m{arch=platform-os-target}       shortcut for all three above
 
-    cross-compiling:
-      @m{os=backend} or @m{os=be}           build for compute node (backend)
-      @m{os=frontend} or @m{os=fe}          build for login node (frontend)
-
     dependencies:
       ^dependency [constraints]     specify constraints on dependencies
       ^@K{/hash}                        build with a specific installed
diff --git a/lib/spack/spack/compilers/__init__.py b/lib/spack/spack/compilers/__init__.py
index af40945c373..4ca2aa3bb08 100644
--- a/lib/spack/spack/compilers/__init__.py
+++ b/lib/spack/spack/compilers/__init__.py
@@ -801,17 +801,17 @@ def _extract_compiler_paths(spec: "spack.spec.Spec") -> Optional[Dict[str, str]]
     def _extract_os_and_target(spec: "spack.spec.Spec"):
         if not spec.architecture:
             host_platform = spack.platforms.host()
-            operating_system = host_platform.operating_system("default_os")
-            target = host_platform.target("default_target")
+            operating_system = host_platform.default_operating_system()
+            target = host_platform.default_target()
         else:
             target = spec.architecture.target
             if not target:
-                target = spack.platforms.host().target("default_target")
+                target = spack.platforms.host().default_target()
 
             operating_system = spec.os
             if not operating_system:
                 host_platform = spack.platforms.host()
-                operating_system = host_platform.operating_system("default_os")
+                operating_system = host_platform.default_operating_system()
         return operating_system, target
 
 
diff --git a/lib/spack/spack/main.py b/lib/spack/spack/main.py
index 33fb308adb4..2c353a3e59c 100644
--- a/lib/spack/spack/main.py
+++ b/lib/spack/spack/main.py
@@ -728,7 +728,7 @@ def _compatible_sys_types():
     with the current host.
     """
     host_platform = spack.platforms.host()
-    host_os = str(host_platform.operating_system("default_os"))
+    host_os = str(host_platform.default_operating_system())
     host_target = archspec.cpu.host()
     compatible_targets = [host_target] + host_target.ancestors
 
diff --git a/lib/spack/spack/platforms/__init__.py b/lib/spack/spack/platforms/__init__.py
index 04a44db5163..f38fa604971 100644
--- a/lib/spack/spack/platforms/__init__.py
+++ b/lib/spack/spack/platforms/__init__.py
@@ -52,8 +52,7 @@ def use_platform(new_platform):
 
     import spack.config
 
-    msg = '"{0}" must be an instance of Platform'
-    assert isinstance(new_platform, Platform), msg.format(new_platform)
+    assert isinstance(new_platform, Platform), f'"{new_platform}" must be an instance of Platform'
 
     original_host_fn = host
 
diff --git a/lib/spack/spack/platforms/_platform.py b/lib/spack/spack/platforms/_platform.py
index fd91bac91d2..a219198c3fb 100644
--- a/lib/spack/spack/platforms/_platform.py
+++ b/lib/spack/spack/platforms/_platform.py
@@ -1,42 +1,22 @@
 # Copyright Spack Project Developers. See COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import warnings
 from typing import Optional
 
 import archspec.cpu
 
 import llnl.util.lang
 
-import spack.error
-
-
-class NoPlatformError(spack.error.SpackError):
-    def __init__(self):
-        msg = "Could not determine a platform for this machine"
-        super().__init__(msg)
-
 
 @llnl.util.lang.lazy_lexicographic_ordering
 class Platform:
     """Platform is an abstract class extended by subclasses.
 
-    To add a new type of platform (such as cray_xe), create a subclass and set all the
-    class attributes such as priority, front_target, back_target, front_os, back_os.
-
     Platform also contain a priority class attribute. A lower number signifies higher
     priority. These numbers are arbitrarily set and can be changed though often there
     isn't much need unless a new platform is added and the user wants that to be
     detected first.
-
-    Targets are created inside the platform subclasses. Most architecture (like linux,
-    and darwin) will have only one target family (x86_64) but in the case of Cray
-    machines, there is both a frontend and backend processor. The user can specify
-    which targets are present on front-end and back-end architecture.
-
-    Depending on the platform, operating systems are either autodetected or are
-    set. The user can set the frontend and backend operating setting by the class
-    attributes front_os and back_os. The operating system will be responsible for
-    compiler detection.
     """
 
     # Subclass sets number. Controls detection order
@@ -45,82 +25,72 @@ class attributes such as priority, front_target, back_target, front_os, back_os.
     #: binary formats used on this platform; used by relocation logic
     binary_formats = ["elf"]
 
-    front_end: Optional[str] = None
-    back_end: Optional[str] = None
-    default: Optional[str] = None  # The default back end target.
-
-    front_os: Optional[str] = None
-    back_os: Optional[str] = None
-    default_os: Optional[str] = None
+    default: str
+    default_os: str
 
     reserved_targets = ["default_target", "frontend", "fe", "backend", "be"]
     reserved_oss = ["default_os", "frontend", "fe", "backend", "be"]
+    deprecated_names = ["frontend", "fe", "backend", "be"]
 
     def __init__(self, name):
         self.targets = {}
         self.operating_sys = {}
         self.name = name
+        self._init_targets()
 
     def add_target(self, name: str, target: archspec.cpu.Microarchitecture) -> None:
-        """Used by the platform specific subclass to list available targets.
-        Raises an error if the platform specifies a name
-        that is reserved by spack as an alias.
-        """
         if name in Platform.reserved_targets:
-            msg = "{0} is a spack reserved alias and cannot be the name of a target"
-            raise ValueError(msg.format(name))
+            msg = f"{name} is a spack reserved alias and cannot be the name of a target"
+            raise ValueError(msg)
         self.targets[name] = target
 
-    def _add_archspec_targets(self):
+    def _init_targets(self):
+        self.default = archspec.cpu.host().name
         for name, microarchitecture in archspec.cpu.TARGETS.items():
             self.add_target(name, microarchitecture)
 
     def target(self, name):
-        """This is a getter method for the target dictionary
-        that handles defaulting based on the values provided by default,
-        front-end, and back-end. This can be overwritten
-        by a subclass for which we want to provide further aliasing options.
-        """
-        # TODO: Check if we can avoid using strings here
         name = str(name)
-        if name == "default_target":
+        if name in Platform.deprecated_names:
+            warnings.warn(f"target={name} is deprecated, use target={self.default} instead")
+
+        if name in Platform.reserved_targets:
             name = self.default
-        elif name == "frontend" or name == "fe":
-            name = self.front_end
-        elif name == "backend" or name == "be":
-            name = self.back_end
 
         return self.targets.get(name, None)
 
     def add_operating_system(self, name, os_class):
-        """Add the operating_system class object into the
-        platform.operating_sys dictionary.
-        """
-        if name in Platform.reserved_oss:
-            msg = "{0} is a spack reserved alias and cannot be the name of an OS"
-            raise ValueError(msg.format(name))
+        if name in Platform.reserved_oss + Platform.deprecated_names:
+            msg = f"{name} is a spack reserved alias and cannot be the name of an OS"
+            raise ValueError(msg)
         self.operating_sys[name] = os_class
 
+    def default_target(self):
+        return self.target(self.default)
+
+    def default_operating_system(self):
+        return self.operating_system(self.default_os)
+
     def operating_system(self, name):
-        if name == "default_os":
+        if name in Platform.deprecated_names:
+            warnings.warn(f"os={name} is deprecated, use os={self.default_os} instead")
+
+        if name in Platform.reserved_oss:
             name = self.default_os
-        if name == "frontend" or name == "fe":
-            name = self.front_os
-        if name == "backend" or name == "be":
-            name = self.back_os
 
         return self.operating_sys.get(name, None)
 
     def setup_platform_environment(self, pkg, env):
-        """Subclass can override this method if it requires any
-        platform-specific build environment modifications.
+        """Platform-specific build environment modifications.
+
+        This method is meant toi be overridden by subclasses, when needed.
         """
         pass
 
     @classmethod
     def detect(cls):
-        """Return True if the the host platform is detected to be the current
-        Platform class, False otherwise.
+        """Returns True if the host platform is detected to be the current Platform class,
+        False otherwise.
 
         Derived classes are responsible for implementing this method.
         """
@@ -135,11 +105,7 @@ def __str__(self):
     def _cmp_iter(self):
         yield self.name
         yield self.default
-        yield self.front_end
-        yield self.back_end
         yield self.default_os
-        yield self.front_os
-        yield self.back_os
 
         def targets():
             for t in sorted(self.targets.values()):
diff --git a/lib/spack/spack/platforms/darwin.py b/lib/spack/spack/platforms/darwin.py
index a1259445562..f6264e291a9 100644
--- a/lib/spack/spack/platforms/darwin.py
+++ b/lib/spack/spack/platforms/darwin.py
@@ -4,8 +4,6 @@
 
 import platform as py_platform
 
-import archspec.cpu
-
 from spack.operating_systems.mac_os import MacOs
 from spack.version import Version
 
@@ -19,18 +17,8 @@ class Darwin(Platform):
 
     def __init__(self):
         super().__init__("darwin")
-        self._add_archspec_targets()
-
-        self.default = archspec.cpu.host().name
-        self.front_end = self.default
-        self.back_end = self.default
-
         mac_os = MacOs()
-
         self.default_os = str(mac_os)
-        self.front_os = str(mac_os)
-        self.back_os = str(mac_os)
-
         self.add_operating_system(str(mac_os), mac_os)
 
     @classmethod
diff --git a/lib/spack/spack/platforms/freebsd.py b/lib/spack/spack/platforms/freebsd.py
index 8ef84e8a12e..c2b2d0d96cd 100644
--- a/lib/spack/spack/platforms/freebsd.py
+++ b/lib/spack/spack/platforms/freebsd.py
@@ -3,8 +3,6 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import platform
 
-import archspec.cpu
-
 from spack.operating_systems.freebsd import FreeBSDOs
 
 from ._platform import Platform
@@ -15,18 +13,8 @@ class FreeBSD(Platform):
 
     def __init__(self):
         super().__init__("freebsd")
-
-        self._add_archspec_targets()
-
-        # Get specific default
-        self.default = archspec.cpu.host().name
-        self.front_end = self.default
-        self.back_end = self.default
-
         os = FreeBSDOs()
         self.default_os = str(os)
-        self.front_os = self.default_os
-        self.back_os = self.default_os
         self.add_operating_system(str(os), os)
 
     @classmethod
diff --git a/lib/spack/spack/platforms/linux.py b/lib/spack/spack/platforms/linux.py
index dda925d0933..8a30d5e21a7 100644
--- a/lib/spack/spack/platforms/linux.py
+++ b/lib/spack/spack/platforms/linux.py
@@ -3,8 +3,6 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import platform
 
-import archspec.cpu
-
 from spack.operating_systems.linux_distro import LinuxDistro
 
 from ._platform import Platform
@@ -15,18 +13,8 @@ class Linux(Platform):
 
     def __init__(self):
         super().__init__("linux")
-
-        self._add_archspec_targets()
-
-        # Get specific default
-        self.default = archspec.cpu.host().name
-        self.front_end = self.default
-        self.back_end = self.default
-
         linux_dist = LinuxDistro()
         self.default_os = str(linux_dist)
-        self.front_os = self.default_os
-        self.back_os = self.default_os
         self.add_operating_system(str(linux_dist), linux_dist)
 
     @classmethod
diff --git a/lib/spack/spack/platforms/test.py b/lib/spack/spack/platforms/test.py
index e6aa8508958..e4246bf4461 100644
--- a/lib/spack/spack/platforms/test.py
+++ b/lib/spack/spack/platforms/test.py
@@ -16,31 +16,19 @@ class Test(Platform):
     if platform.system().lower() == "darwin":
         binary_formats = ["macho"]
 
-    if platform.machine() == "arm64":
-        front_end = "aarch64"
-        back_end = "m1"
-        default = "m1"
-    else:
-        front_end = "x86_64"
-        back_end = "core2"
-        default = "core2"
-
-    front_os = "redhat6"
-    back_os = "debian6"
     default_os = "debian6"
+    default = "m1" if platform.machine() == "arm64" else "core2"
 
     def __init__(self, name=None):
         name = name or "test"
         super().__init__(name)
-        self.add_target(self.default, archspec.cpu.TARGETS[self.default])
-        self.add_target(self.front_end, archspec.cpu.TARGETS[self.front_end])
+        self.add_operating_system("debian6", spack.operating_systems.OperatingSystem("debian", 6))
+        self.add_operating_system("redhat6", spack.operating_systems.OperatingSystem("redhat", 6))
 
-        self.add_operating_system(
-            self.default_os, spack.operating_systems.OperatingSystem("debian", 6)
-        )
-        self.add_operating_system(
-            self.front_os, spack.operating_systems.OperatingSystem("redhat", 6)
-        )
+    def _init_targets(self):
+        targets = ("aarch64", "m1") if platform.machine() == "arm64" else ("x86_64", "core2")
+        for t in targets:
+            self.add_target(t, archspec.cpu.TARGETS[t])
 
     @classmethod
     def detect(cls):
diff --git a/lib/spack/spack/platforms/windows.py b/lib/spack/spack/platforms/windows.py
index edfb68b074b..f50d3fe4dd0 100755
--- a/lib/spack/spack/platforms/windows.py
+++ b/lib/spack/spack/platforms/windows.py
@@ -4,8 +4,6 @@
 
 import platform
 
-import archspec.cpu
-
 from spack.operating_systems.windows_os import WindowsOs
 
 from ._platform import Platform
@@ -16,18 +14,8 @@ class Windows(Platform):
 
     def __init__(self):
         super().__init__("windows")
-        self._add_archspec_targets()
-
-        self.default = archspec.cpu.host().name
-        self.front_end = self.default
-        self.back_end = self.default
-
         windows_os = WindowsOs()
-
         self.default_os = str(windows_os)
-        self.front_os = str(windows_os)
-        self.back_os = str(windows_os)
-
         self.add_operating_system(str(windows_os), windows_os)
 
     @classmethod
diff --git a/lib/spack/spack/reporters/cdash.py b/lib/spack/spack/reporters/cdash.py
index edc2696ec50..4368aa5dd09 100644
--- a/lib/spack/spack/reporters/cdash.py
+++ b/lib/spack/spack/reporters/cdash.py
@@ -106,7 +106,7 @@ def __init__(self, configuration: CDashConfiguration):
         self.site = configuration.site or socket.gethostname()
         self.osname = platform.system()
         self.osrelease = platform.release()
-        self.target = spack.platforms.host().target("default_target")
+        self.target = spack.platforms.host().default_target()
         self.starttime = int(time.time())
         self.endtime = self.starttime
         self.buildstamp = (
diff --git a/lib/spack/spack/spec.py b/lib/spack/spack/spec.py
index 293c9691067..78202b65e98 100644
--- a/lib/spack/spack/spec.py
+++ b/lib/spack/spack/spec.py
@@ -237,23 +237,14 @@ def _make_microarchitecture(name: str) -> archspec.cpu.Microarchitecture:
 class ArchSpec:
     """Aggregate the target platform, the operating system and the target microarchitecture."""
 
-    @staticmethod
-    def _return_arch(os_tag, target_tag):
-        platform = spack.platforms.host()
-        default_os = platform.operating_system(os_tag)
-        default_target = platform.target(target_tag)
-        arch_tuple = str(platform), str(default_os), str(default_target)
-        return ArchSpec(arch_tuple)
-
     @staticmethod
     def default_arch():
         """Return the default architecture"""
-        return ArchSpec._return_arch("default_os", "default_target")
-
-    @staticmethod
-    def frontend_arch():
-        """Return the frontend architecture"""
-        return ArchSpec._return_arch("frontend", "frontend")
+        platform = spack.platforms.host()
+        default_os = platform.default_operating_system()
+        default_target = platform.default_target()
+        arch_tuple = str(platform), str(default_os), str(default_target)
+        return ArchSpec(arch_tuple)
 
     __slots__ = "_platform", "_os", "_target"
 
@@ -5191,12 +5182,10 @@ def get_host_environment_metadata() -> Dict[str, str]:
 
 
 def get_host_environment() -> Dict[str, Any]:
-    """Return a dictionary (lookup) with host information (not including the
-    os.environ).
-    """
+    """Returns a dictionary with host information (not including the os.environ)."""
     host_platform = spack.platforms.host()
-    host_target = host_platform.target("default_target")
-    host_os = host_platform.operating_system("default_os")
+    host_target = host_platform.default_target()
+    host_os = host_platform.default_operating_system()
     arch_fmt = "platform={0} os={1} target={2}"
     arch_spec = Spec(arch_fmt.format(host_platform, host_os, host_target))
     return {
diff --git a/lib/spack/spack/test/architecture.py b/lib/spack/spack/test/architecture.py
index 04e89fc80b5..8562be992f1 100644
--- a/lib/spack/spack/test/architecture.py
+++ b/lib/spack/spack/test/architecture.py
@@ -60,8 +60,7 @@ def test_user_input_combination(config, target_str, os_str):
     """Test for all the valid user input combinations that both the target and
     the operating system match.
     """
-    spec_str = "libelf os={} target={}".format(os_str, target_str)
-    spec = Spec(spec_str)
+    spec = Spec(f"libelf os={os_str} target={target_str}")
     assert spec.architecture.os == str(TEST_PLATFORM.operating_system(os_str))
     assert spec.architecture.target == TEST_PLATFORM.target(target_str)
 
@@ -71,8 +70,8 @@ def test_default_os_and_target(default_mock_concretization):
     after concretization.
     """
     spec = default_mock_concretization("libelf")
-    assert spec.architecture.os == str(TEST_PLATFORM.operating_system("default_os"))
-    assert spec.architecture.target == TEST_PLATFORM.target("default_target")
+    assert spec.architecture.os == str(TEST_PLATFORM.default_operating_system())
+    assert spec.architecture.target == TEST_PLATFORM.default_target()
 
 
 def test_operating_system_conversion_to_dict():
diff --git a/lib/spack/spack/test/cmd/debug.py b/lib/spack/spack/test/cmd/debug.py
index 33944fbc6f8..e8e87746dc9 100644
--- a/lib/spack/spack/test/cmd/debug.py
+++ b/lib/spack/spack/test/cmd/debug.py
@@ -51,8 +51,8 @@ def test_create_db_tarball(tmpdir, database):
 def test_report():
     out = debug("report")
     host_platform = spack.platforms.host()
-    host_os = host_platform.operating_system("frontend")
-    host_target = host_platform.target("frontend")
+    host_os = host_platform.default_operating_system()
+    host_target = host_platform.default_target()
     architecture = spack.spec.ArchSpec((str(host_platform), str(host_os), str(host_target)))
 
     assert spack.get_version() in out
diff --git a/lib/spack/spack/test/cmd/env.py b/lib/spack/spack/test/cmd/env.py
index f8408b736cb..661ba7a1995 100644
--- a/lib/spack/spack/test/cmd/env.py
+++ b/lib/spack/spack/test/cmd/env.py
@@ -2614,7 +2614,7 @@ def test_stack_yaml_remove_from_matrix_no_effect(tmpdir):
     - packages:
         - matrix:
             - [mpileaks, callpath]
-            - [target=be]
+            - [target=default_target]
   specs:
     - $packages
 """
@@ -2639,7 +2639,7 @@ def test_stack_yaml_force_remove_from_matrix(tmpdir):
     - packages:
         - matrix:
             - [mpileaks, callpath]
-            - [target=be]
+            - [target=default_target]
   specs:
     - $packages
 """
@@ -2659,7 +2659,7 @@ def test_stack_yaml_force_remove_from_matrix(tmpdir):
 
             assert before_user == after_user
 
-            mpileaks_spec = Spec("mpileaks target=be")
+            mpileaks_spec = Spec("mpileaks target=default_target")
             assert mpileaks_spec in before_conc
             assert mpileaks_spec not in after_conc
 
diff --git a/lib/spack/spack/test/concretization/core.py b/lib/spack/spack/test/concretization/core.py
index d0521b4369c..0950e227ea9 100644
--- a/lib/spack/spack/test/concretization/core.py
+++ b/lib/spack/spack/test/concretization/core.py
@@ -148,7 +148,6 @@ def current_host(request, monkeypatch):
     cpu, _, is_preference = request.param.partition("-")
 
     monkeypatch.setattr(spack.platforms.Test, "default", cpu)
-    monkeypatch.setattr(spack.platforms.Test, "front_end", cpu)
     if not is_preference:
         target = archspec.cpu.TARGETS[cpu]
         monkeypatch.setattr(archspec.cpu, "host", lambda: target)
@@ -385,10 +384,11 @@ def test_different_compilers_get_different_flags(
     ):
         """Tests that nodes get the flags of the associated compiler."""
         mutable_config.set("compilers", [clang12_with_flags, gcc11_with_flags])
+        t = archspec.cpu.host().family
         client = spack.concretize.concretize_one(
             Spec(
-                "cmake-client %gcc@11.1.0 platform=test os=fe target=fe"
-                " ^cmake %clang@12.2.0 platform=test os=fe target=fe"
+                f"cmake-client %gcc@11.1.0 platform=test os=redhat6 target={t}"
+                f" ^cmake %clang@12.2.0 platform=test os=redhat6 target={t}"
             )
         )
         cmake = client["cmake"]
@@ -413,7 +413,8 @@ def test_spec_flags_maintain_order(self, mutable_config, gcc11_with_flags):
     def test_compiler_flags_differ_identical_compilers(self, mutable_config, clang12_with_flags):
         mutable_config.set("compilers", [clang12_with_flags])
         # Correct arch to use test compiler that has flags
-        spec = Spec("pkg-a %clang@12.2.0 platform=test os=fe target=fe")
+        t = archspec.cpu.host().family
+        spec = Spec(f"pkg-a %clang@12.2.0 platform=test os=redhat6 target={t}")
 
         # Get the compiler that matches the spec (
         compiler = spack.compilers.compiler_for_spec("clang@=12.2.0", spec.architecture)
@@ -2111,14 +2112,15 @@ def test_installed_specs_disregard_conflicts(self, mutable_database, monkeypatch
     def test_require_targets_are_allowed(self, mutable_database):
         """Test that users can set target constraints under the require attribute."""
         # Configuration to be added to packages.yaml
-        external_conf = {"all": {"require": "target=%s" % spack.platforms.test.Test.front_end}}
+        required_target = archspec.cpu.TARGETS[spack.platforms.test.Test.default].family
+        external_conf = {"all": {"require": f"target={required_target}"}}
         spack.config.set("packages", external_conf)
 
         with spack.config.override("concretizer:reuse", False):
             spec = spack.concretize.concretize_one("mpich")
 
         for s in spec.traverse():
-            assert s.satisfies("target=%s" % spack.platforms.test.Test.front_end)
+            assert s.satisfies(f"target={required_target}")
 
     def test_external_python_extensions_have_dependency(self):
         """Test that python extensions have access to a python dependency
diff --git a/lib/spack/spack/test/config.py b/lib/spack/spack/test/config.py
index 11829ed92bc..5682135ee26 100644
--- a/lib/spack/spack/test/config.py
+++ b/lib/spack/spack/test/config.py
@@ -408,7 +408,7 @@ def test_substitute_config_variables(mock_low_high_config, monkeypatch):
         os.path.join("foo", "$platform", "bar")
     ) == os.path.abspath(os.path.join("foo", "test", "bar"))
 
-    host_target = spack.platforms.host().target("default_target")
+    host_target = spack.platforms.host().default_target()
     host_target_family = str(host_target.family)
     assert spack_path.canonicalize_path(
         os.path.join("foo", "$target_family", "bar")
diff --git a/lib/spack/spack/test/conftest.py b/lib/spack/spack/test/conftest.py
index f907c6c54ff..ceabdc53a13 100644
--- a/lib/spack/spack/test/conftest.py
+++ b/lib/spack/spack/test/conftest.py
@@ -621,7 +621,7 @@ def linux_os():
     platform = spack.platforms.host()
     name, version = "debian", "6"
     if platform.name == "linux":
-        current_os = platform.operating_system("default_os")
+        current_os = platform.default_operating_system()
         name, version = current_os.name, current_os.version
     LinuxOS = collections.namedtuple("LinuxOS", ["name", "version"])
     return LinuxOS(name=name, version=version)
@@ -680,7 +680,6 @@ def load_json():
 def mock_targets(mock_uarch_configuration, monkeypatch):
     """Use this fixture to enable mock uarch targets for testing."""
     targets_json, targets = mock_uarch_configuration
-
     monkeypatch.setattr(archspec.cpu.schema, "TARGETS_JSON", targets_json)
     monkeypatch.setattr(archspec.cpu.microarchitecture, "TARGETS", targets)
 
diff --git a/lib/spack/spack/test/cray_manifest.py b/lib/spack/spack/test/cray_manifest.py
index 42585f55fa7..f04a51c0b0d 100644
--- a/lib/spack/spack/test/cray_manifest.py
+++ b/lib/spack/spack/test/cray_manifest.py
@@ -13,6 +13,8 @@
 
 import pytest
 
+import archspec.cpu
+
 import spack
 import spack.cmd
 import spack.cmd.external
@@ -98,11 +100,8 @@ def spec_json(self):
 
 @pytest.fixture
 def _common_arch(test_platform):
-    return JsonArchEntry(
-        platform=test_platform.name,
-        os=test_platform.front_os,
-        target=test_platform.target("fe").name,
-    )
+    generic = archspec.cpu.TARGETS[test_platform.default].family
+    return JsonArchEntry(platform=test_platform.name, os="redhat6", target=generic.name)
 
 
 @pytest.fixture
diff --git a/lib/spack/spack/test/spec_dag.py b/lib/spack/spack/test/spec_dag.py
index 5f366b44f61..8a39f07dbdd 100644
--- a/lib/spack/spack/test/spec_dag.py
+++ b/lib/spack/spack/test/spec_dag.py
@@ -319,7 +319,6 @@ def test_dependents_and_dependencies_are_correct(self):
             ("mpich@1.0", "mpileaks ^mpich@2.0"),
             ("mpich%gcc", "mpileaks ^mpich%intel"),
             ("mpich%gcc@4.6", "mpileaks ^mpich%gcc@4.5"),
-            ("mpich platform=test target=be", "mpileaks ^mpich platform=test target=fe"),
         ],
     )
     def test_unsatisfiable_cases(self, set_dependency, constraint_str, spec_str):
diff --git a/lib/spack/spack/test/spec_semantics.py b/lib/spack/spack/test/spec_semantics.py
index 8cac90a46cf..668677c44d9 100644
--- a/lib/spack/spack/test/spec_semantics.py
+++ b/lib/spack/spack/test/spec_semantics.py
@@ -460,7 +460,6 @@ def test_concrete_specs_which_satisfies_abstract(self, lhs, rhs, default_mock_co
             ("foo platform=linux", "platform=test os=redhat6 target=x86"),
             ("foo os=redhat6", "platform=test os=debian6 target=x86_64"),
             ("foo target=x86_64", "platform=test os=redhat6 target=x86"),
-            ("foo arch=test-frontend-frontend", "platform=test os=frontend target=backend"),
             ("foo%intel", "%gcc"),
             ("foo%intel", "%gcc"),
             ("foo%gcc@4.3", "%gcc@4.4:4.6"),
@@ -487,7 +486,6 @@ def test_concrete_specs_which_satisfies_abstract(self, lhs, rhs, default_mock_co
             ("libelf+debug", "libelf~debug"),
             ("libelf+debug~foo", "libelf+debug+foo"),
             ("libelf debug=True", "libelf debug=False"),
-            ("libelf platform=test target=be os=be", "libelf target=fe os=fe"),
             ("namespace=builtin.mock", "namespace=builtin"),
         ],
     )
diff --git a/lib/spack/spack/test/spec_syntax.py b/lib/spack/spack/test/spec_syntax.py
index e00fb3a7eee..4f58be0b2c3 100644
--- a/lib/spack/spack/test/spec_syntax.py
+++ b/lib/spack/spack/test/spec_syntax.py
@@ -306,7 +306,7 @@ def _specfile_for(spec_str, filename):
         (
             r"os=fe",  # Various translations associated with the architecture
             [Token(SpecTokens.KEY_VALUE_PAIR, value="os=fe")],
-            "arch=test-redhat6-None",
+            "arch=test-debian6-None",
         ),
         (
             r"os=default_os",
@@ -999,14 +999,14 @@ def test_disambiguate_hash_by_spec(spec1, spec2, constraint, mock_packages, monk
         ("x arch=linux-rhel7-ppc64le arch=linux-rhel7-x86_64", "two architectures"),
         ("y ^x arch=linux-rhel7-x86_64 arch=linux-rhel7-x86_64", "two architectures"),
         ("y ^x arch=linux-rhel7-x86_64 arch=linux-rhel7-ppc64le", "two architectures"),
-        ("x os=fe os=fe", "'os'"),
-        ("x os=fe os=be", "'os'"),
-        ("x target=fe target=fe", "'target'"),
-        ("x target=fe target=be", "'target'"),
+        ("x os=redhat6 os=debian6", "'os'"),
+        ("x os=debian6 os=redhat6", "'os'"),
+        ("x target=core2 target=x86_64", "'target'"),
+        ("x target=x86_64 target=core2", "'target'"),
         ("x platform=test platform=test", "'platform'"),
         # TODO: these two seem wrong: need to change how arch is initialized (should fail on os)
-        ("x os=fe platform=test target=fe os=fe", "'platform'"),
-        ("x target=be platform=test os=be os=fe", "'platform'"),
+        ("x os=debian6 platform=test target=default_target os=redhat6", "two architectures"),
+        ("x target=default_target platform=test os=redhat6 os=debian6", "'platform'"),
         # Dependencies
         ("^[@foo] zlib", "edge attributes"),
         ("x ^[deptypes=link]foo ^[deptypes=run]foo", "conflicting dependency types"),
diff --git a/lib/spack/spack/util/path.py b/lib/spack/spack/util/path.py
index 49a0b5e240b..87542415fd0 100644
--- a/lib/spack/spack/util/path.py
+++ b/lib/spack/spack/util/path.py
@@ -29,8 +29,8 @@ def architecture():
     import spack.spec
 
     host_platform = spack.platforms.host()
-    host_os = host_platform.operating_system("default_os")
-    host_target = host_platform.target("default_target")
+    host_os = host_platform.default_operating_system()
+    host_target = host_platform.default_target()
 
     return spack.spec.ArchSpec((str(host_platform), str(host_os), str(host_target)))
 
diff --git a/share/spack/spack-completion.fish b/share/spack/spack-completion.fish
index 41ae4c91c3d..a920426f8f7 100644
--- a/share/spack/spack-completion.fish
+++ b/share/spack/spack-completion.fish
@@ -506,9 +506,9 @@ complete -c spack -n '__fish_spack_using_command arch' -s o -l operating-system
 complete -c spack -n '__fish_spack_using_command arch' -s t -l target -f -a target
 complete -c spack -n '__fish_spack_using_command arch' -s t -l target -d 'print only the target'
 complete -c spack -n '__fish_spack_using_command arch' -s f -l frontend -f -a frontend
-complete -c spack -n '__fish_spack_using_command arch' -s f -l frontend -d 'print frontend'
+complete -c spack -n '__fish_spack_using_command arch' -s f -l frontend -d 'print frontend (DEPRECATED)'
 complete -c spack -n '__fish_spack_using_command arch' -s b -l backend -f -a backend
-complete -c spack -n '__fish_spack_using_command arch' -s b -l backend -d 'print backend'
+complete -c spack -n '__fish_spack_using_command arch' -s b -l backend -d 'print backend (DEPRECATED)'
 
 # spack audit
 set -g __fish_spack_optspecs_spack_audit h/help
diff --git a/var/spack/repos/builtin/packages/quantum-espresso/package.py b/var/spack/repos/builtin/packages/quantum-espresso/package.py
index 490a114577a..cc180d0356c 100644
--- a/var/spack/repos/builtin/packages/quantum-espresso/package.py
+++ b/var/spack/repos/builtin/packages/quantum-espresso/package.py
@@ -500,18 +500,6 @@ def install(self, pkg, spec, prefix):
         prefix_path = prefix.bin if "@:5.4.0" in spec else prefix
         options = ["-prefix={0}".format(prefix_path)]
 
-        # This additional flag is needed anytime the target architecture
-        # does not match the host architecture, which results in a binary that
-        # configure cannot execute on the login node. This is how we detect
-        # cross compilation: If the platform is NOT either Linux or Darwin
-        # and the target=backend, that we are in the cross-compile scenario
-        # scenario. This should cover Cray, BG/Q, and other custom platforms.
-        # The other option is to list out all the platform where you would be
-        # cross compiling explicitly.
-        if not (spec.satisfies("platform=linux") or spec.satisfies("platform=darwin")):
-            if spec.satisfies("target=backend"):
-                options.append("--host")
-
         # QE autoconf compiler variables has some limitations:
         # 1. There is no explicit MPICC variable so we must re-purpose
         #    CC for the case of MPI.