From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <508999F4.6060802@advaoptical.com>
Date: Thu, 25 Oct 2012 21:58:44 +0200
From: Oded Gabbay <ogabbay@advaoptical.com>
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Subject: [Xenomai] Problem with rtdm_mmap_to_user
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To: xenomai@xenomai.org

Hi,

I'm using Xenomai 2.6.1 and kernel 2.6.33 on mpc8309 (powerpc) processor.

I'm trying to map a kernel memory area to user space memory.

The call to rtdm_mmap_to_user inside the rt driver works but when I read 
the memory in the user space thread (rt thread), the contents of the 
memory area are wrong.

Here is the code in the driver:

         ret = rtdm_mmap_to_user(user_info, skb, sizeof(struct rtskb), 
PROT_READ|PROT_WRITE,
                                 (void **)&msg->msg_iov[1].iov_base, 
NULL, NULL);


msg->msg_iov[1].iov_base is a void* which points to NULL before the call 
to rtdm_mmap_to_user.

The result is in msg->msg_iov[1].iov_base. The address seems good, as it 
in the range of the addresses of other variables in my user space thread.

In the user-space thread I do:

             void *tmp;
             tmp = msg->msg_iov[1].iov_base;
             printf("tmp = %p:%x\n", tmp, *(int *)tmp);

The results is that tmp points to the same address I got at 
rtdm_mmap_to_user, but the contents of tmp are wrong.

Please help me...

Thanks,
Oded