site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com Hi Folks, I am using a synchronous write call in filter scheme driver. I have created a IOMemoryDescriptor buffer by calling withAddress function and pass this buffer to the sync write call, but i am getting crash when this write routine gets called. My code snippet for the same is as follows: void com_My_driver::write(IOService* provider, UInt64 byteStart, IOMemoryDescriptor* buffer, IOStorageCompletion completion) { // Allocate a buffer to write the data on disk. UInt32 WriteBufSize = 512; char * bufWrite = new char[512]; strcpy(bufWrite, "DRIVER ON MACOS X"); // Create memory descriptor for the buffer IOMemoryDescriptor *WriteBuffer = NULL; WriteBuffer = IOMemoryDescriptor::withAddress((void*) bufWrite, (IOByteCount) WriteBufSize, kIODirectionOut); if(WriteBuffer) { filteredMedia->write(this, 512, WriteBuffer); /* crashing just here and getting memory access exception*/ } else { WriteBuffer->release(); WriteBuffer = 0; } Is it i am missing something while using the sync write call? I am able to make the code work if I do memory allocations in User Client and successfully do the write() on disk. But not able to do the same if I don’t use user client and do allocation in filter scheme driver. I think I am not using memory management functions correctly. Is there any documentation available,how to use IOMemoryDescriptor in kernel level drivers? I have read KernelProgramming.pdf, WritingDeviceDrivers.pdf but I didn’t find it useful in my case. Look forward to pointers so that I can solve this issue. Thanks in advance, Yogesh Pahilwan _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... This email sent to site_archiver@lists.apple.com