In article
<6ca4e552-9eda-4645-bf5f-483700048228@[EMAIL PROTECTED]
>,
Robert Spykerman <robert.spykerman@[EMAIL PROTECTED]
> wrote:
> On May 1, 2:11 am, Ben Artin <mac...@[EMAIL PROTECTED]
> wrote: ...
> > That is particularly true on Mac OS X, where syscalls are not the
primitive
> > way for userland code to communicate with the kernel -- Mach IPC is,
and
> > syscalls are layered on top of Mach IPC. So, by using syscalls you are
> > *already* one layer above the kernel. If you want to be as close to
the
> > kernel as possible, then you need to use Mach APIs directly; they tend
to
> > be painfully complicated to call if you've never seen them before. If
you
> > want to avoid the pain, you might as well use fork() in the C library,
> > which I believe will not have weird calling conventions.
>
> Heh, Mach IPC eh?
>
> Now you've got me REALLY interested. I live for pain by the way lol,
gonna
> check this mach API out just for the heck of it.
>
> So I imagine this mach IPC API is glue that allows stuff outside the
kernel
> proper like device drivers and like to talk to the kernel and with each
> other, I would imagine? Damn, there's a lot I still need to learn.
Basically, one of the fundamental concepts in the Mach kernel is that of a
Mach
****t, which represents an access-controlled communication channel. It can
be
used for two processes to talk to each other, two threads to talk to each
other,
userland-to-kernel communication, driver-to-kernel communication, etc.
Essentially every kernel API (thread management, process management, VM,
file
systems, networking, etc) is implemented as Mach messages to kernel's Mach
****ts. You can see more about this in kernel sources
> I'll go google some mach IPC stuff but if you've got some really good
primer
> links, I'd be very grateful if you could share them with me :) Thanks
again.
Check out
<http://developer.apple.com/do***entation/Darwin/Conceptual/KernelProgramming/>
and the kernel sources. In particular, the folder at
<http://www.opensource.apple.com/darwinsource/10.5.2/xnu-1228.3.13/osfmk/mach/>
contains a bunch of .defs files which contain the IPC specifications for
kernel
APIs.
For example, thread_act.defs contains the following:
/*
* Assign thread to processor set.
*/
routine thread_assign(
thread : thread_act_t;
new_set : processor_set_t);
as part of the API for controlling thread processor affinity. The file
/usr/include/mach/thread_act.h is generated from that during the kernel
compilation process, and the above declaration turns into:
extern
kern_return_t thread_assign
(
thread_act_t thread,
processor_set_t new_set
);
hth
Ben
--
If this message helped you, consider buying an item
from my wish list: <http://artins.org/ben/wishlist>
|
