Date: Thu, 28 Aug 2014 18:41:50 +0000 (GMT) From: Steven Stewart-Gallus <sstewartgallus00@mylangara.bc.ca> To: freebsd-hackers@freebsd.org Subject: Can anyone help clarify details about the FreeBSD system call interface? Message-ID: <fb4bf68f53c5.53ff77ee@langara.bc.ca>
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Hi, I am interested in learning more about how FreeBSD works. I have
gathered some information on some of FreeBSD's undocumented system
calls and am not sure it is correct. Please correct me if I am wrong
about the following system calls. I would be happy to submit some
patches to help out with documentation after I get some confirmation
and clarification.
int sys_yield(void);
int sys_sched_yield(void);
Not sure how sys_yield differs from sched_yield. sys_yield is defined
in sys/kern/kern_synch.c and sys_sched_yield is defined in
sys/kern/p1003_1b.c.
int sys_sstk(int incr);
sys/vm/vm_mmap.c defines this as:
/*
* MPSAFE
*/
/* ARGSUSED */
int
sys_sstk(td, uap)
struct thread *td;
struct sstk_args *uap;
{
/* Not yet implemented */
return (EOPNOTSUPP);
}
Did sys_sstk use to do something in the past and is now just legacy?
int sys_vadvise(int anom);
sys/vm/vm_unix.c defines this as:
/*
* MPSAFE
*/
/* ARGSUSED */
int
sys_ovadvise(td, uap)
struct thread *td;
struct ovadvise_args *uap;
{
/* START_GIANT_OPTIONAL */
/* END_GIANT_OPTIONAL */
return (EINVAL);
}
Did sys_vadvise use to do something in the past and is now just
legacy?
int sys_mac_syscall(const char * policy, int call, void * arg);
Not sure what sys_mac_syscall does. Seems to do a bunch of MAC
operations at once. See sys/security/mac for a closer look.
int sys___mac_execve(char * fname, char ** argv, char ** envv, struct
mac * mac_p);
Looks an execve that applys a MAC policy. See sys/security/mac for a
closer look.
int sys__umtx_lock(struct umtx * umtx);
int sys _umtx_unlock(struct umtx * umtx);
int sys__umtx_op(void * obj, int op, u_long val, void * uaddr1, void *
uaddr2);
Seems to implement low level mutexes. See sys/kern/kern_umtx.c for a
closer look and lib/libthr/thread/umtx.h for the userspace wrapper.
int sys_nlm_syscall(int debug_level, int grace_period, int addr_count,
char ** addrs);
Multiplexes system calls used to implement the kernel side of the
Network Lock Manager protocol. See sys/nlm for a closer look.
int sys_nnpfs_syscall(int operation, char * a_pathP, int a_opcode,
void * a_paramsP, int a_followSymlinks);
Multiplexes system calls used to implement the kernel side of some
filesystem thingy. Not sure what it does. I can't find out where
this is defined in the source code.
int sys_afs3_syscall(long syscall, long parm1, long parm2, long parm3,
long parm4, long parm5, long parm6);
Multiplexes system calls used to implement the kernel side of the AFS
protocol (version 3). I can't find out where this is defined in the
source code.
Thank you,
Steven Stewart-Gallus
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