On 10/27/2011 3:31 AM, Daniel Grech wrote:
Hi,I am allocating memory from a device driver in the kernel and passing it on to another driver. In the other driver it is neccessary for me to determine whether the address passed is from user space or kernel space as this driver can also be called from user space. I am currently using the following check to determine if the address is in kernel space or userspace : if ( ( (char *) VM_MIN_KERNEL_ADDRESS<= address)&& (address<= (char *) VM_MAX_KERNEL_ADDRESS) ) { KERNEL SPACE } else { USER SPACE } However, this does not always work. Sometimes although I allocate memory in the kernel using the malloc macro, this returns an address which is not in the above range. Is there any workaround for this problem? Thanks in advance for your help. Daniel _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[email protected]"
Be careful if using user virtual addresses in DMA POST commands, because the interrupt handler may not have the the same address space as the caller. For example: BUS_DMASYNC_POSTREAD copying a bounce buffer to a user VA.
--Mark Tinguely _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[email protected]"
