diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index d572cc06f..df64d2247 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -2419,85 +2419,97 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
       <not-uninit/>
     </arg>
   </function>
-  <!-- int    sched_get_priority_max(int); -->
+  <!-- https://pubs.opengroup.org/onlinepubs/9699919799/functions/sched_get_priority_max.html -->
+  <!-- int sched_get_priority_max(int policy); -->
   <function name="sched_get_priority_max">
     <returnValue type="int"/>
     <noreturn>false</noreturn>
-    <arg nr="1">
+    <use-retval/>
+    <arg nr="1" direction="in">
       <not-uninit/>
       <not-bool/>
     </arg>
   </function>
-  <!-- int    sched_get_priority_min(int); -->
+  <!-- int sched_get_priority_min(int policy); -->
   <function name="sched_get_priority_min">
     <returnValue type="int"/>
     <noreturn>false</noreturn>
-    <arg nr="1">
+    <use-retval/>
+    <arg nr="1" direction="in">
       <not-uninit/>
       <not-bool/>
     </arg>
   </function>
-  <!-- int    sched_getparam(pid_t, struct sched_param *); -->
+  <!-- https://pubs.opengroup.org/onlinepubs/9699919799/functions/sched_getparam.html -->
+  <!-- int sched_getparam(pid_t pid, struct sched_param *param); -->
   <function name="sched_getparam">
     <returnValue type="int"/>
     <noreturn>false</noreturn>
-    <arg nr="1">
+    <arg nr="1" direction="in">
       <not-uninit/>
+      <valid>0:</valid>
     </arg>
-    <arg nr="2">
+    <arg nr="2" direction="out">
       <not-null/>
       <not-bool/>
     </arg>
   </function>
-  <!-- int    sched_getscheduler(pid_t); -->
+  <!-- https://pubs.opengroup.org/onlinepubs/9699919799/functions/sched_getscheduler.html -->
+  <!-- int sched_getscheduler(pid_t pid); -->
   <function name="sched_getscheduler">
     <returnValue type="int"/>
     <noreturn>false</noreturn>
-    <arg nr="1">
+    <arg nr="1" direction="in">
       <not-uninit/>
       <not-bool/>
+      <valid>0:</valid>
     </arg>
   </function>
-  <!-- int    sched_rr_get_interval(pid_t, struct timespec *); -->
+  <!-- https://pubs.opengroup.org/onlinepubs/9699919799/functions/sched_rr_get_interval.html -->
+  <!-- int sched_rr_get_interval(pid_t pid, struct timespec *interval); -->
   <function name="sched_rr_get_interval">
     <noreturn>false</noreturn>
     <returnValue type="int"/>
-    <arg nr="1">
+    <arg nr="1" direction="in">
       <not-uninit/>
     </arg>
-    <arg nr="2">
+    <arg nr="2" direction="out">
       <not-null/>
       <not-bool/>
     </arg>
   </function>
-  <!-- int    sched_setparam(pid_t, const struct sched_param *); -->
+  <!-- https://pubs.opengroup.org/onlinepubs/9699919799/functions/sched_setparam.html# -->
+  <!-- int sched_setparam(pid_t pid, const struct sched_param *param); -->
   <function name="sched_setparam">
     <returnValue type="int"/>
     <noreturn>false</noreturn>
-    <arg nr="1">
+    <arg nr="1" direction="in">
       <not-uninit/>
     </arg>
-    <arg nr="2">
+    <arg nr="2" direction="in">
       <not-uninit/>
       <not-bool/>
     </arg>
   </function>
-  <!-- int    sched_setscheduler(pid_t, int, const struct sched_param *); -->
+  <!-- https://pubs.opengroup.org/onlinepubs/9699919799/functions/sched_setscheduler.html -->
+  <!-- int sched_setscheduler(pid_t pid, int policy, const struct sched_param *param); -->
   <function name="sched_setscheduler">
     <returnValue type="int"/>
     <noreturn>false</noreturn>
-    <arg nr="1">
+    <arg nr="1" direction="in">
+      <not-uninit/>
+      <valid>0:</valid>
+    </arg>
+    <arg nr="2" direction="in">
       <not-uninit/>
     </arg>
-    <arg nr="2">
-      <not-uninit/>
-    </arg>
-    <arg nr="3">
+    <arg nr="3" direction="in">
       <not-uninit/>
       <not-bool/>
     </arg>
   </function>
-  <!-- int    sched_yield(void); -->
+  <!-- https://pubs.opengroup.org/onlinepubs/9699919799/functions/sched_yield.html -->
+  <!-- int sched_yield(void); -->
   <function name="sched_yield">
     <returnValue type="int"/>
     <noreturn>false</noreturn>