[v4,2/2] target: Add system emulation aiming to target any architecture

diff --git a/configure b/configure
index 3cd736b139..57f6c7038b 100755
--- a/configure
+++ b/configure
@@ -194,6 +194,7 @@  EXTRA_LDFLAGS=""
 # Distributions want to ensure that several features are compiled in, and it
 # is impossible without a --enable-foo that exits if a feature is not found.
 default_feature=""
+target_system_any=""
 
 for opt do
   optarg=$(expr "x$opt" : 'x[^=]*=\(.*\)')
@@ -693,6 +694,8 @@  for opt do
   ;;
   --without-default-features) # processed above
   ;;
+  --enable-experimental-system-binary-that-may-break-dont-do-this-distros) target_system_any="yes"
+  ;;
   --static) static="yes"
   ;;
   --host=*|--build=*|\
@@ -834,6 +837,9 @@  fi
 
 for config in $mak_wilds; do
     target="$(basename "$config" .mak)"
+    if [ "$target" = any-softmmu ] && [ "$target_system_any" != yes ]; then
+        continue
+    fi
     if echo "$target_list_exclude" | grep -vq "$target"; then
         default_target_list="${default_target_list} $target"
     fi
diff --git a/configs/devices/any-softmmu/default.mak b/configs/devices/any-softmmu/default.mak
new file mode 100644
index 0000000000..dab0ce770e
--- /dev/null
+++ b/configs/devices/any-softmmu/default.mak
@@ -0,0 +1,9 @@ 
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+CONFIG_ISA_BUS=y
+CONFIG_PCI=y
+CONFIG_PCI_DEVICES=y
+CONFIG_I2C=y
+CONFIG_TPM=y
+CONFIG_NUBUS=y
+CONFIG_VIRTIO=y
diff --git a/configs/targets/any-softmmu.mak b/configs/targets/any-softmmu.mak
new file mode 100644
index 0000000000..2c6cf1edd4
--- /dev/null
+++ b/configs/targets/any-softmmu.mak
@@ -0,0 +1,3 @@ 
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+TARGET_ARCH=any
diff --git a/meson.build b/meson.build
index 51b995f4c7..a4fe9f23d0 100644
--- a/meson.build
+++ b/meson.build
@@ -3051,7 +3051,9 @@  foreach target : target_dirs
     if default_targets
       continue
     endif
-    error('No accelerator available for target @0@'.format(target))
+    if 'any-softmmu' not in target_dirs
+      error('No accelerator available for target @0@'.format(target))
+    endif
   endif
 
   actual_target_dirs += target
@@ -3909,16 +3911,21 @@  foreach target : target_dirs
                  name_suffix: 'fa')
 
   if target.endswith('-softmmu')
+    if target_name == 'any'
+      qemu_system_name = 'x-qemu-system-🚧'
+    else
+      qemu_system_name = 'qemu-system-' + target_name
+    endif
     execs = [{
-      'name': 'qemu-system-' + target_name,
+      'name': qemu_system_name,
       'win_subsystem': 'console',
       'sources': files('system/main.c'),
       'dependencies': [],
-      'install': true
+      'install': target_name != 'any'
     }]
     if host_os == 'windows' and (sdl.found() or gtk.found())
       execs += [{
-        'name': 'qemu-system-' + target_name + 'w',
+        'name': qemu_system_name + 'w',
         'win_subsystem': 'windows',
         'sources': files('system/main.c'),
         'dependencies': [],
diff --git a/qapi/machine.json b/qapi/machine.json
index bb5a178909..970aac2364 100644
--- a/qapi/machine.json
+++ b/qapi/machine.json
@@ -36,7 +36,7 @@ 
              'mips64el', 'mipsel', 'nios2', 'or1k', 'ppc',
              'ppc64', 'riscv32', 'riscv64', 'rx', 's390x', 'sh4',
              'sh4eb', 'sparc', 'sparc64', 'tricore',
-             'x86_64', 'xtensa', 'xtensaeb' ] }
+             'x86_64', 'xtensa', 'xtensaeb', 'any' ] }
 
 ##
 # @CpuS390State:
diff --git a/include/sysemu/arch_init.h b/include/sysemu/arch_init.h
index 8850cb1a14..49bee75610 100644
--- a/include/sysemu/arch_init.h
+++ b/include/sysemu/arch_init.h
@@ -4,6 +4,7 @@ 
 
 enum {
     QEMU_ARCH_ALL = -1,
+    QEMU_ARCH_ANY = -1,
     QEMU_ARCH_ALPHA = (1 << 0),
     QEMU_ARCH_ARM = (1 << 1),
     QEMU_ARCH_CRIS = (1 << 2),
diff --git a/target/any/cpu-param.h b/target/any/cpu-param.h
new file mode 100644
index 0000000000..42e38ae991
--- /dev/null
+++ b/target/any/cpu-param.h
@@ -0,0 +1,13 @@ 
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef ANY_CPU_PARAM_H
+#define ANY_CPU_PARAM_H
+
+#define TARGET_LONG_BITS 64
+
+#define TARGET_PHYS_ADDR_SPACE_BITS 64 /* MAX(targets) */
+#define TARGET_VIRT_ADDR_SPACE_BITS 64 /* MAX(targets) */
+
+#define TARGET_PAGE_BITS_VARY
+#define TARGET_PAGE_BITS_MIN  10 /* MIN(targets)=ARMv5/ARMv6, ignoring AVR */
+
+#endif
diff --git a/target/any/cpu-qom.h b/target/any/cpu-qom.h
new file mode 100644
index 0000000000..18d6a85de9
--- /dev/null
+++ b/target/any/cpu-qom.h
@@ -0,0 +1,12 @@ 
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef QEMU_DUMMY_CPU_QOM_H
+#define QEMU_DUMMY_CPU_QOM_H
+
+#include "hw/core/cpu.h"
+#include "qom/object.h"
+
+#define TYPE_DUMMY_CPU "dummy-cpu"
+
+OBJECT_DECLARE_CPU_TYPE(DUMMYCPU, CPUClass, DUMMY_CPU)
+
+#endif
diff --git a/target/any/cpu.h b/target/any/cpu.h
new file mode 100644
index 0000000000..e8abb8891f
--- /dev/null
+++ b/target/any/cpu.h
@@ -0,0 +1,24 @@ 
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef TARGET_ANY_CPU_H
+#define TARGET_ANY_CPU_H
+
+#include "cpu-qom.h"
+#include "exec/cpu-defs.h"
+
+#define DUMMY_CPU_TYPE_SUFFIX "-" TYPE_DUMMY_CPU
+#define DUMMY_CPU_TYPE_NAME(name) (name DUMMY_CPU_TYPE_SUFFIX)
+#define CPU_RESOLVING_TYPE TYPE_DUMMY_CPU
+
+struct CPUArchState {
+    /* nothing here */
+};
+
+struct ArchCPU {
+    CPUState parent_obj;
+
+    CPUArchState env;
+};
+
+#include "exec/cpu-all.h" /* FIXME remove once exec/ headers cleaned */
+
+#endif
diff --git a/.gitlab-ci.d/buildtest.yml b/.gitlab-ci.d/buildtest.yml
index a1c030337b..493a868bfc 100644
--- a/.gitlab-ci.d/buildtest.yml
+++ b/.gitlab-ci.d/buildtest.yml
@@ -729,3 +729,24 @@  pages:
       - public
   variables:
     QEMU_JOB_PUBLISH: 1
+
+build-system-any:
+  extends:
+    - .native_build_job_template
+  needs:
+    - job: amd64-alpine-container
+  variables:
+    IMAGE: alpine
+    TARGETS: any-softmmu
+    MAKE_CHECK_ARGS: check-qtest
+    CONFIGURE_ARGS:
+      --disable-tools
+      --disable-hvf
+      --disable-kvm
+      --disable-nvmm
+      --disable-tcg
+      --disable-whpx
+      --disable-xen
+      --with-default-devices
+      --enable-qom-cast-debug
+      --enable-experimental-system-binary-that-may-break-dont-do-this-distros
diff --git a/hw/any/meson.build b/hw/any/meson.build
new file mode 100644
index 0000000000..60e1567e53
--- /dev/null
+++ b/hw/any/meson.build
@@ -0,0 +1,5 @@ 
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+any_ss = ss.source_set()
+
+hw_arch += {'any': any_ss}
diff --git a/hw/meson.build b/hw/meson.build
index 463d702683..644eeee938 100644
--- a/hw/meson.build
+++ b/hw/meson.build
@@ -47,6 +47,7 @@  subdir('xenpv')
 subdir('fsi')
 
 subdir('alpha')
+subdir('any')
 subdir('arm')
 subdir('avr')
 subdir('cris')
diff --git a/meson_options.txt b/meson_options.txt
index 0a99a059ec..afae66ad1c 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -368,3 +368,6 @@  option('qemu_ga_version', type: 'string', value: '',
 
 option('hexagon_idef_parser', type : 'boolean', value : true,
        description: 'use idef-parser to automatically generate TCG code for the Hexagon frontend')
+
+option('experimental-system-binary-that-may-break-dont-do-this-distros', type : 'boolean', value : false,
+       description: 'build experimental qemu-system-any binary with no particular target architecture')
diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
index 680fa3f581..85f5aec267 100644
--- a/scripts/meson-buildoptions.sh
+++ b/scripts/meson-buildoptions.sh
@@ -32,6 +32,9 @@  meson_options_help() {
   printf "%s\n" '  --enable-debug-stack-usage'
   printf "%s\n" '                           measure coroutine stack usage'
   printf "%s\n" '  --enable-debug-tcg       TCG debugging'
+  printf "%s\n" '  --enable-experimental-system-binary-that-may-break-dont-do-this-distros'
+  printf "%s\n" '                           build experimental qemu-system-any binary with no'
+  printf "%s\n" '                           particular target architecture'
   printf "%s\n" '  --enable-fdt[=CHOICE]    Whether and how to find the libfdt library'
   printf "%s\n" '                           (choices: auto/disabled/enabled/internal/system)'
   printf "%s\n" '  --enable-fuzzing         build fuzzing targets'
@@ -306,6 +309,8 @@  _meson_option_parse() {
     --disable-docs) printf "%s" -Ddocs=disabled ;;
     --enable-dsound) printf "%s" -Ddsound=enabled ;;
     --disable-dsound) printf "%s" -Ddsound=disabled ;;
+    --enable-experimental-system-binary-that-may-break-dont-do-this-distros) printf "%s" -Dexperimental-system-binary-that-may-break-dont-do-this-distros=true ;;
+    --disable-experimental-system-binary-that-may-break-dont-do-this-distros) printf "%s" -Dexperimental-system-binary-that-may-break-dont-do-this-distros=false ;;
     --enable-fdt) printf "%s" -Dfdt=enabled ;;
     --disable-fdt) printf "%s" -Dfdt=disabled ;;
     --enable-fdt=*) quote_sh "-Dfdt=$2" ;;
diff --git a/target/Kconfig b/target/Kconfig
index 83da0bd293..09109c4884 100644
--- a/target/Kconfig
+++ b/target/Kconfig
@@ -1,4 +1,5 @@ 
 source alpha/Kconfig
+source any/Kconfig
 source arm/Kconfig
 source avr/Kconfig
 source cris/Kconfig
diff --git a/target/any/Kconfig b/target/any/Kconfig
new file mode 100644
index 0000000000..8840d70e55
--- /dev/null
+++ b/target/any/Kconfig
@@ -0,0 +1,4 @@ 
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+config ANY
+    bool
diff --git a/target/any/meson.build b/target/any/meson.build
new file mode 100644
index 0000000000..4f5422d3a3
--- /dev/null
+++ b/target/any/meson.build
@@ -0,0 +1,7 @@ 
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+any_ss = ss.source_set()
+any_system_ss = ss.source_set()
+
+target_arch += {'any': any_ss}
+target_system_arch += {'any': any_system_ss}
diff --git a/target/meson.build b/target/meson.build
index dee2ac47e0..c75b91e1b9 100644
--- a/target/meson.build
+++ b/target/meson.build
@@ -1,4 +1,5 @@ 
 subdir('alpha')
+subdir('any')
 subdir('arm')
 subdir('avr')
 subdir('cris')
diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
index 6ea77893f5..e302d4153e 100644
--- a/tests/qtest/meson.build
+++ b/tests/qtest/meson.build
@@ -355,7 +355,11 @@  foreach dir : target_dirs
   endif
 
   target_base = dir.split('-')[0]
-  qtest_emulator = emulators['qemu-system-' + target_base]
+  if target_base == 'any'
+    qtest_emulator = emulators['x-qemu-system-🚧']
+  else
+    qtest_emulator = emulators['qemu-system-' + target_base]
+  endif
   target_qtests = get_variable('qtests_' + target_base, []) + qtests_generic
 
   test_deps = roms