Generate the syscall numbers from the installed header that has them.
Ideally, we'd use FreeBSD's lua infra for this, but that requires that
we have those files installed, and they aren't quite the same across
supported versions yet, so use this simple, but effective hack. Add to
meson build, but unused.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com>
Signed-off-by: Warner Losh <imp@bsdimp.com>
---
 bsd-user/freebsd/meson.build           | 10 ++++++++--
 bsd-user/freebsd/scripts/syscallhdr.sh |  9 +++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)
 create mode 100644 bsd-user/freebsd/scripts/syscallhdr.sh

diff --git a/bsd-user/freebsd/meson.build b/bsd-user/freebsd/meson.build
index 8fd6c7cfb8..38f2debf7e 100644
--- a/bsd-user/freebsd/meson.build
+++ b/bsd-user/freebsd/meson.build
@@ -1,6 +1,12 @@
+bsd_syscall_nr = custom_target('bsd-syscall-h',
+    output: '@BASENAME@_nr.h',
+    input: ['/usr/include/sys/syscall.h'],
+    command: [sh, meson.current_source_dir() / 'scripts/syscallhdr.sh', '@INPUT@', '@OUTPUT@', 'FREEBSD'])
+
 bsd_user_ss.add(files(
   'os-stat.c',
   'os-proc.c',
   'os-sys.c',
-  'os-syscall.c',
-))
+  'os-syscall.c'),
+  bsd_syscall_nr
+)
diff --git a/bsd-user/freebsd/scripts/syscallhdr.sh b/bsd-user/freebsd/scripts/syscallhdr.sh
new file mode 100644
index 0000000000..fa38500775
--- /dev/null
+++ b/bsd-user/freebsd/scripts/syscallhdr.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+# Copyright (c) 2026 Warner Losh <imp@bsdimp.com>
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+in="$1"
+out="$2"
+bsd="$3"
+
+awk -v bsd="$3" '{sub("SYS_", "TARGET_" bsd "_NR_", $0); print;}' < $in > $out
-- 
2.52.0