Re: notify_no_senders oddity

[Samuel Thibault]

Richard Braun, le Sun 31 Dec 2006 17:11:55 +0100, a écrit :
> On Sun, Dec 31, 2006 at 12:30:24PM +0100, Samuel Thibault wrote:
> > There's something I don't understand in
> > i386/i386at/i386at_ds_routines.c:ds_notify()
> > 
> >       dev = (device_t) ns->not_header.msgh_remote_port;
> > 
> > How a port can be a device_t?
> 
> In include/mach/message.h:
> 
> typedef struct {
>   ...
>   mach_port_t msgh_remote_port;
>   ...
> } mach_msg_header_t;
> 
> and in include/device/device_types.h
> 
> typedef mach_port_t device_t;
> 
> I'm not totally sure of what you call a `port' in your question.

Well, I actually don't know much details about mach ports :)

More specifically, I'm talking about an ipc_port_t, as used for instance
in linux/dev/glue/block.c in device_open()

  bd->port = ipc_port_alloc_kernel ();

and just a few lines below,

  ipc_port_nsrequest (bd->port, 1, notify, &notify);

which eventually calls ipc_notify_no_senders() which does

  n->not_header.msgh_remote_port = (mach_port_t) port;

Hence casting ipc_port_t into mach_port_t, which later is converted to
device_t as I said:

> >       dev = (device_t) ns->not_header.msgh_remote_port;

Samuel


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