diff --git a/.cirrus.yml b/.cirrus.yml
index c306ac97..1ccd6173 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -7,11 +7,12 @@ freebsd_task:
   env:
     matrix:
       - OCAML_VERSION: 5.3.0
+      - OCAML_VERSION: 5.4.0
   pkg_install_script: pkg install -y ocaml-opam gmp gmake pkgconf bash
   setup_script:
     - opam init -a --comp=$OCAML_VERSION
     - opam update
-    - opam install dune
+    - opam install dune fmt
     - opam pin add -n -t .
     - opam depext -yt ocaml-solo5
     - opam install -t ocaml-solo5 --deps-only
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index af6f6606..bf893dd7 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -4,7 +4,9 @@ jobs:
   test:
     strategy:
       matrix:
-        ocaml-compiler: [5.3.0]
+        ocaml-compiler:
+          - 5.3.0
+          - 5.4.0
     name: OCaml ${{ matrix.ocaml-compiler }}
     runs-on: ubuntu-latest
     steps:
@@ -16,7 +18,7 @@ jobs:
           *.opam
           !ocaml-solo5-cross-aarch64.opam
     - name: Install ocaml-solo5 and dune
-      run: opam install ocaml-solo5 conf-libseccomp dune
+      run: opam install ocaml-solo5 conf-libseccomp dune fmt
     - name: Show the toolchain configuration
       run: |
         set -x
@@ -25,6 +27,13 @@ jobs:
         opam exec -- ocamlfind -toolchain solo5 list
     - name: Compile examples with hvt
       run: MODE=hvt opam exec -- dune build --root example
+    - name: Run the hello example with hvt
+      run: |
+        set -x
+        MODE=hvt opam exec -- dune describe location --root example \
+          --context solo5 --no-print-directory ./hello.exe |& tee hello.path
+        sudo setfacl -m u:${USER}:rw /dev/kvm
+        opam exec -- solo5-hvt -- "example/$(cat hello.path)"
     - name: Compile examples with spt
       run: MODE=spt opam exec -- dune build --root example
     - name: Run examples with spt
diff --git a/example/dune.inc b/example/dune.inc
index b885dfbd..5cfc9a76 100644
--- a/example/dune.inc
+++ b/example/dune.inc
@@ -10,7 +10,7 @@
   ; Force linking the manifest in
   -cclib
   "-u __solo5_mft1_note")
- (libraries solo5os)
+ (libraries solo5os fmt)
  (modes native))
 
 (rule
diff --git a/example/dune_gen.ml b/example/dune_gen.ml
index 508ad818..b5581cf2 100644
--- a/example/dune_gen.ml
+++ b/example/dune_gen.ml
@@ -52,7 +52,7 @@ let print_rule test exitcode extraifs extralibs =
     exitcode
 
 let _ =
-  print_rule "hello" None [] [];
+  print_rule "hello" None [] ["fmt"];
   print_rule "sysfail" (Some 2) [] [];
   print_rule "config" None [] [];
   print_rule "compilerlibsx86" None
diff --git a/example/hello.ml b/example/hello.ml
index ef16b82d..92c8f033 100644
--- a/example/hello.ml
+++ b/example/hello.ml
@@ -1 +1 @@
-let () = Printf.printf "Hello from OCaml on Solo5!\n%!";;
+let () = Fmt.pr "Hello from OCaml on Solo5!\n%!";;
diff --git a/nolibc/include/pthread.h b/nolibc/include/pthread.h
index ea7b5651..dce1f329 100644
--- a/nolibc/include/pthread.h
+++ b/nolibc/include/pthread.h
@@ -54,4 +54,7 @@ int pthread_cond_broadcast(pthread_cond_t *);
 int pthread_cond_signal(pthread_cond_t *);
 int pthread_cond_destroy(pthread_cond_t *);
 
+int pthread_cancel(pthread_t thread);
+void pthread_exit(void *retval);
+
 #endif
diff --git a/nolibc/include/sys/time.h b/nolibc/include/sys/time.h
index f39c30fa..0f71b30c 100644
--- a/nolibc/include/sys/time.h
+++ b/nolibc/include/sys/time.h
@@ -12,5 +12,9 @@ struct timezone {
     int tz_dsttime;
 };
 int gettimeofday(struct timeval *tv, struct timezone *tz);
+struct timespec {
+    time_t tv_sec;
+    long tv_nsec;
+};
 
 #endif
diff --git a/nolibc/stubs.c b/nolibc/stubs.c
index 54942217..774110bb 100644
--- a/nolibc/stubs.c
+++ b/nolibc/stubs.c
@@ -147,6 +147,8 @@ STUB_ABORT(pthread_cond_signal);
 STUB_IGNORE(int, pthread_cond_broadcast, 0);
 STUB_ABORT(pthread_self);
 STUB_ABORT(pthread_detach);
+STUB_IGNORE(int, pthread_cancel, 0);
+STUB_ABORT(pthread_exit);
 
 STUB_IGNORE(int, sigfillset, 0);
 STUB_ABORT(sigwait);
diff --git a/ocaml-solo5-cross-aarch64.opam b/ocaml-solo5-cross-aarch64.opam
index bb8975c5..6cbc4656 100644
--- a/ocaml-solo5-cross-aarch64.opam
+++ b/ocaml-solo5-cross-aarch64.opam
@@ -31,7 +31,7 @@ depends: [
   "opatch" {build} # to patch the compiler sources
   "ocamlfind" {build}
   "ocaml-src" {build}
-  "ocaml" {= "5.3.0"}
+  "ocaml" {= "5.3.0" | = "5.4.0"}
   "solo5" {>= "0.9.1"}
   "solo5-cross-aarch64" {>= "0.9.1" }
 ]
diff --git a/ocaml-solo5.opam b/ocaml-solo5.opam
index 684c2766..95a688bf 100644
--- a/ocaml-solo5.opam
+++ b/ocaml-solo5.opam
@@ -31,7 +31,7 @@ depends: [
   "opatch" {build} # to patch the compiler sources
   "ocamlfind" {build}
   "ocaml-src" {build}
-  "ocaml" {= "5.3.0"}
+  "ocaml" {= "5.3.0" | = "5.4.0"}
   "solo5" {>= "0.9.1"}
 ]
 conflicts: [
diff --git a/patches/5.4.0/0001-Accept-native-freestanding-targets-at-configure-time.patch b/patches/5.4.0/0001-Accept-native-freestanding-targets-at-configure-time.patch
new file mode 100644
index 00000000..47432f34
--- /dev/null
+++ b/patches/5.4.0/0001-Accept-native-freestanding-targets-at-configure-time.patch
@@ -0,0 +1,68 @@
+From fb64bf56cd52896765a53007aa723a4346ef12c4 Mon Sep 17 00:00:00 2001
+From: Samuel Hym <samuel@tarides.com>
+Date: Mon, 26 Feb 2024 19:35:26 +0100
+Subject: [PATCH 1/3] Accept native freestanding targets at configure time
+
+Accept `*-none` and `*-elf*` triplets for all the architectures with a
+native backend to describe the corresponding freestanding target; `none`
+and `elf*` are the most commonly-used last components in triplets for
+freestanding targets
+Set `system` to `none` in such cases
+---
+ configure    | Bin 737974 -> 738624 bytes
+ configure.ac |  14 +++++++++++++-
+ 2 files changed, 13 insertions(+), 1 deletion(-)
+
+diff --git a/configure b/configure
+index 8bb7306cb1..1f0c06d943 100755
+--- a/configure
++++ b/configure
+@@ -18612,7 +18612,19 @@ fi ;; #(
+   riscv64-*-linux*) :
+     has_native_backend=yes; arch=riscv; model=riscv64; system=linux ;; #(
+   x86_64-*-gnu*) :
+-    has_native_backend=yes; arch=amd64; system=gnu
++    has_native_backend=yes; arch=amd64; system=gnu ;; #(
++  aarch64-*-none|arm64-*-none|aarch64-*-elf*|arm64-*-elf*) :
++    has_native_backend=yes; arch=arm64; system=none ;; #(
++  powerpc64le*-*-none|powerpc64le*-*-elf*) :
++    has_native_backend=yes; arch=power; model=ppc64le; system=none ;; #(
++  powerpc64*-*-none|powerpc64*-*-elf*) :
++    has_native_backend=yes; arch=power; model=ppc64; system=none ;; #(
++  riscv64-*-none|riscv64-*-elf*) :
++    has_native_backend=yes; arch=riscv; model=riscv64; system=none ;; #(
++  s390x*-*-none|s390x*-*-elf*) :
++    has_native_backend=yes; arch=s390x; model=z10; system=none ;; #(
++  x86_64-*-none|x86_64-*-elf*) :
++    has_native_backend=yes; arch=amd64; system=none
+  ;; #(
+   *) :
+      ;;
+diff --git a/configure.ac b/configure.ac
+index 0535f404b0..8e5e1e9300 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -1609,7 +1609,19 @@ AS_CASE([$target],
+   [riscv64-*-linux*],
+     [has_native_backend=yes; arch=riscv; model=riscv64; system=linux],
+   [x86_64-*-gnu*],
+-    [has_native_backend=yes; arch=amd64; system=gnu]
++    [has_native_backend=yes; arch=amd64; system=gnu],
++  [aarch64-*-none|arm64-*-none|aarch64-*-elf*|arm64-*-elf*],
++    [has_native_backend=yes; arch=arm64; system=none],
++  [powerpc64le*-*-none|powerpc64le*-*-elf*],
++    [has_native_backend=yes; arch=power; model=ppc64le; system=none],
++  [powerpc64*-*-none|powerpc64*-*-elf*],
++    [has_native_backend=yes; arch=power; model=ppc64; system=none],
++  [riscv64-*-none|riscv64-*-elf*],
++    [has_native_backend=yes; arch=riscv; model=riscv64; system=none],
++  [s390x*-*-none|s390x*-*-elf*],
++    [has_native_backend=yes; arch=s390x; model=z10; system=none],
++  [x86_64-*-none|x86_64-*-elf*],
++    [has_native_backend=yes; arch=amd64; system=none]
+ )
+ 
+ AS_CASE([$arch],
+-- 
+2.51.0
+
diff --git a/patches/5.4.0/0002-Allow-ocaml-in-a-triplet-target-to-build-freestandin.patch b/patches/5.4.0/0002-Allow-ocaml-in-a-triplet-target-to-build-freestandin.patch
new file mode 100644
index 00000000..9272c800
--- /dev/null
+++ b/patches/5.4.0/0002-Allow-ocaml-in-a-triplet-target-to-build-freestandin.patch
@@ -0,0 +1,81 @@
+From 126ef9d01e512a82c6cd79bf74d0b3e9e9d5cec0 Mon Sep 17 00:00:00 2001
+From: Samuel Hym <samuel@tarides.com>
+Date: Mon, 26 Feb 2024 11:51:11 +0100
+Subject: [PATCH 2/3] Allow `ocaml` in a triplet target to build freestanding
+ cross compilers
+
+Allow `ocaml` to be used as the last component of the target triplet in
+case we are using a custom toolchain for a freestanding target. The
+target triplet is then temporarily rewritten to "<arch>-none" to compute
+the canonical target.
+
+This allows to use a `*-*-ocaml-` prefixes (ie `x86_64-solo5-ocaml-`) to
+create cross-compiler toolchains dedicated to specific freestanding
+targets
+---
+ configure    | Bin 738624 -> 739110 bytes
+ configure.ac |  13 +++++++++++++
+ 2 files changed, 13 insertions(+)
+
+diff --git a/configure b/configure
+index 1f0c06d943..04f729c00c 100755
+--- a/configure
++++ b/configure
+@@ -3690,6 +3690,21 @@ IFS=$ac_save_IFS
+ case $host_os in *\ *) host_os=`echo "$host_os" | sed 's/ /-/g'`;; esac
+ 
+ 
++# Allow "ocaml" to be used as the last component of the target triplet in case
++# we are using a custom toolchain for a freestanding target. To do so, the
++# target triplet is temporarily rewritten to "<arch>-none" to compute the
++# canonical target
++save_target_alias="$target_alias"
++case $target_alias in #(
++  *-*-ocaml) :
++    ac_save_IFS=$IFS
++    IFS='-'
++    set x $target_alias
++    target_alias="$2-none"
++    IFS=$ac_save_IFS ;; #(
++  *) :
++     ;;
++esac
+ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking target system type" >&5
+ printf %s "checking target system type... " >&6; }
+ if test ${ac_cv_target+y}
+@@ -3730,6 +3745,7 @@ test -n "$target_alias" &&
+   test "$program_prefix$program_suffix$program_transform_name" = \
+     NONENONEs,x,x, &&
+   program_prefix=${target_alias}-
++target_alias="$save_target_alias"
+ 
+ # Override cross_compiling and ac_tool_prefix variables since the C toolchain is
+ # used to generate target code when building a cross compiler
+diff --git a/configure.ac b/configure.ac
+index 8e5e1e9300..d634d70bf2 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -302,7 +302,20 @@ AC_CONFIG_COMMANDS_PRE(OCAML_QUOTED_STRING_ID)
+ 
+ AC_CANONICAL_BUILD
+ AC_CANONICAL_HOST
++# Allow "ocaml" to be used as the last component of the target triplet in case
++# we are using a custom toolchain for a freestanding target. To do so, the
++# target triplet is temporarily rewritten to "<arch>-none" to compute the
++# canonical target
++save_target_alias="$target_alias"
++AS_CASE([$target_alias],
++  [*-*-ocaml],
++    [ac_save_IFS=$IFS
++    IFS='-'
++    set x $target_alias
++    target_alias="$2-none"
++    IFS=$ac_save_IFS])
+ AC_CANONICAL_TARGET
++target_alias="$save_target_alias"
+ 
+ # Override cross_compiling and ac_tool_prefix variables since the C toolchain is
+ # used to generate target code when building a cross compiler
+-- 
+2.51.0
+
diff --git a/patches/5.4.0/0003-Set-Max_domains_-def-max-to-1.patch b/patches/5.4.0/0003-Set-Max_domains_-def-max-to-1.patch
new file mode 100644
index 00000000..6f82569a
--- /dev/null
+++ b/patches/5.4.0/0003-Set-Max_domains_-def-max-to-1.patch
@@ -0,0 +1,44 @@
+From 038db6e2efd54d13a6841b250f9efe338eea72e2 Mon Sep 17 00:00:00 2001
+From: Samuel Hym <samuel@tarides.com>
+Date: Fri, 12 Apr 2024 19:21:52 +0200
+Subject: [PATCH 3/3] Set `Max_domains_{def,max}` to 1
+
+Solo5 is single-core with no scheduler, so avoid the useless memory
+waste
+
+Note that since PR#13272 the maximum number of domains can set using a
+parameter in `OCAMLRUNPARAM` so a patchless implementation could be to
+add to `nolibc`:
+- a `secure_getenv` returning `"d=1"` for the `OCAMLRUNPARAM` value,
+- a `sscanf`; it could be hard-coded version just for that use case
+  (namely recover the `1`)
+but this would still be rather brittle
+---
+ runtime/caml/domain.h | 8 ++------
+ 1 file changed, 2 insertions(+), 6 deletions(-)
+
+diff --git a/runtime/caml/domain.h b/runtime/caml/domain.h
+index c7d6c1136f..ef3ff52ede 100644
+--- a/runtime/caml/domain.h
++++ b/runtime/caml/domain.h
+@@ -26,15 +26,11 @@
+ #include "mlvalues.h"
+ #include "domain_state.h"
+ 
+-#ifdef ARCH_SIXTYFOUR
+-#define Max_domains_def 128
+-#else
+-#define Max_domains_def 16
+-#endif
++#define Max_domains_def 1
+ 
+ /* Upper limit for the number of domains. Chosen to be arbitrarily large. Used
+  * for sanity checking [max_domains] value in OCAMLRUNPARAM. */
+-#define Max_domains_max 4096
++#define Max_domains_max 1
+ 
+ /* is the minor heap full or an external interrupt has been triggered */
+ Caml_inline int caml_check_gc_interrupt(caml_domain_state * dom_st)
+-- 
+2.51.0
+