1 files changed, 19 insertions, 3 deletions

diff --git a/sys/kern/syscalls.master b/sys/kern/syscalls.master
index b606503e3ba3..315e2692bfa1 100644
--- a/sys/kern/syscalls.master
+++ b/sys/kern/syscalls.master
@@ -49,6 +49,24 @@
 ;		definition to syscall.h besides adding a sysent.
 ;	NOTSTATIC syscall is loadable
 ;	CAPENABLED syscall is allowed in capability mode
+;
+; To support programmatic generation of both the default ABI and 32-bit compat
+; (freebsd32) we impose a number of restrictions on the types of system calls.
+; For integer types:
+;  - Bare int and long are allowed (long is a sign of a bad interface).
+;  - Use u_int and u_long rather than "unsigned (int|long)".
+;  - size_t is allowed.
+;  - typedefs are allowed, but new signed types that vary between 32- and
+;    64-bit ABIs must be added to makesyscalls.lua so it knows they require
+;    handling.
+;  - Always-64-bit types other than dev_t, id_t, and off_t must be added to
+;    makesyscalls.lua.
+; For pointers:
+;  - Prefer structs to typedefs so an ABI-specific suffix (e.g., "32") can
+;    be prepended (e.g., ucontext_t -> struct ucontext -> struct ucontext32).
+;  - Pointers to objects (structs, unions, etc) containing any long, pointer,
+;    or time_t arguments need _Contains_ annotations.  Such objects should be
+;    padded such that all 64-bit types are 64-bit aligned.
 
 ; annotations:
 ;	SAL 2.0 annotations are used to specify how system calls treat
@@ -87,14 +105,12 @@
 ;	timet_	Object contains a time_t and varies between i386 and other
 ;		ABIs.
 
-; Please copy any additions and changes to the following compatability tables:
-; sys/compat/freebsd32/syscalls.master
-
 ; #ifdef's, etc. may be included, and are copied to the output files.
 
 #include <sys/param.h>
 #include <sys/sysent.h>
 #include <sys/sysproto.h>
+%%ABI_HEADERS%%
 
 0	AUE_NULL	STD {
 		int nosys(void);