site_archiver@lists.apple.com Delivered-To: Darwin-dev@lists.apple.com 4) The most likely cause is that your length is bogus; I notice that your buffer "data" (which should not be a stack buffer, it should be allocated!) is 2K in size, but you don't do anything to ensure that your count "bytes" is > 0 and less than 2K, so you could easily be overflowing the buffer. Another possibility is that, since 2K is a heck of a lot of data in kernel terms (1/8th of your entire available stack!!!), you could be trashing the kernel stack, resulting in the panic (this is less likely than simply having a bogus length and smashing your own stack, but it's a possibility). Then it's probably a stack smasher. 5) Finally, if you are using a worker thread to do the work instead of doing it in the context of the process making the call (you should know whether or not you are using one - in fact, you should have told us this when you asked the question...), then it's trying to copy in from kernel_process, which is the wrong process to copy in from. Basically, all copies in or out MUST occur in the context of the process requesting the copy. -- Terry _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... On Jul 19, 2007, at 12:18 PM, JanakiRam wrote: Is this a restriction that we can't send the data more than 2k from user space to kernel space ? . If we need to send more data from user space to general kext , pls suggest ways to do it. No, this is because you are using a stack buffer instead of an allocated buffer. Auto variables are allocated on the stack (this is part of the ISO/ANSI C standard). If you want a large data area, and want to avoid the risk, allocate the memory instead of declaring it to be on the stack (i.e. declare a pointer, allocate the memory, copy into the allocated memory, free the memory when you're done using it). Even after putting the > 0 && < 2k cindition , its still reproducing. I've a user space daemon process which gets created from the main program using pthreads. From User space daemon process i'm calling the ioctl to kernel extension. Do you mean this way of doing it is not the proper way ? If you start a worker thread in the kernel specifically associated with your device driver, then you will not be able to copy in from user space to the kernel. It doesn't sound like you are doing this. This email sent to site_archiver@lists.apple.com