Could you please enable my "state top" patches in the FreeBSD distribution.
I developped the stuff under FreeBSD, so it must be good there :-)
Here is a patch (relative to the RELENG_4 branch).
Thanks,
Frank
pid_t rfork_thread(int forkflags, void *stack, int (*func)(void *arg),
void *arg);
A new process is created, presumably using RFMEM shared address space.
The child process switches to the supplied stack, which is set up with a
function call frame. The function is called with the supplied arguement.
If the function returns, the return value will be used with _exit(2).
was not fun and I am not entirely certain of the correctness, but it seems
to work. (in fact, side by side testing of this code vs the x86 version
turned up hidden bugs in the x86 code).
testing and real-life applications:
1) If you returned from the thread function, you got a segv instead of
calling _exit() with your return code.
2) clean up some bogus stack management. There was also an underflow
on function return.
3) when making syscalls, the kernel is expecting to have to leave space
for the function's return address. We need to duplicate this. It was
an accident that the rfork syscall actually worked here. :-/
the number of times I have given this to people and got asked: why isn't
it in libc? It is impossible to do this without assembler glue to reset
the stack for the new child process.
int rfork_thread(flags, stack_addr, start_fnc, start_arg)
int flags; Flags to rfork system call. See rfork(2).
void *stack_addr; Top of stack for thread.
int (*start_fnc)(void *); Address of thread function to call in child.
void *start_arg; Argument to pass to the thread function in child.
This is deliberately not documented or prototyped in includes until the
corresponding alpha version is written.
gcc's internal exit() prototypes and the (futile) hackery that we did to
try and avoid warnings. main() was renamed for similar reasons.
Remove an exit related hack from makesyscalls.sh.
!VFS_AIO case. Lots of things have hooks into here (kqueue, exit(),
sockets, etc), I elected to keep the external interfaces the same
rather than spread more #ifdefs around the kernel.
Make sysinstall override this on install, so the effective behavioural
change for a newly installed system is null. Overall, this makes a system
with an empty /etc/rc.conf not run any network services, and makes the
FreeBSD-provided network services that are running visible in /etc/rc.conf
(instead of making people look through /etc/defaults/rc.conf to find the
things they need to disable to secure the system.)
Reviewed by: jhb
Discussed with: The usual cabal
"kern/sys_generic.c:358: warning: cast discards qualifiers from pointer
target type"
The idea for using the uintptr_t intermediate cast for de-constifying
a pointer was hinted at by bde some time ago.
