Hi,
Thanks for the info..
i executed shmat() using sys_ipc() which multiplexes all the ipc
functions...
thanks,
raghu.
On Mon, 28 Oct 2002, Ravi wrote:
>
> > I have written a daemon which creates a shared memory and puts in
> > the data. Then i have a kernel module which is always installed
> after
> > starting the daemon. But when I try to access the shared memory that
> > has been created using the daemon I am not seeing any data that has
> > been put in by the daemon.
>
> Shared memory is for communicating between two user space processes.
> It is the wrong approach if you want to pass data between user-space
> and kernel-space. You should use a device interface or use /proc.
>
> > When i print the addresses of the shared memory I see
> > different addresses. I am using the same key_t to in the kernel
> > module ,which i used to create using the daemon, to access the
> > shared memory. I am not understanding what is the problem...
>
> I am not sure how you executed the equivalent of shmat() in the
> kernel module. Even if you did, it would execute in the context of
> some process ('insmod' if you are doing this at module init time).
> Once the process dies, the shared memory mapping is no longer valid.
> This may be the reason why you don't see the expected data.
> But as I said, you shouldn't be doing things this way. So don't
> bother debugging it..
>
> -Ravi.
>
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