site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com Thread-index: AcVVmyk7tDtJYOR/TEyQM0gVRWbn6wAigEHQ Dear Mike, Please go through the below code for our Read issue /***************User Space Application **************************/ /* Purpose: This calls the 'read' method of user client using IOConnectMethodStructureIStructureO */ static kern_return_t MyDoRead(io_connect_t connect) kern_return_t kernResult; MySampleStruct sampleStructIn; // Input structure MySampleStruct sampleStructOut; //Output structure kernResult = vm_allocate(mach_task_self(), (vm_address_t*) &sampleStructIn.buff, vm_page_size, TRUE); if(sampleStructIn.buff) { char* buff = (char*) sampleStructOut.buff; strcpy(buff, ""); } IOByteCount structSizeIn = sizeof(MySampleStruct); IOByteCount structSizeOut = sizeof(MySampleStruct); if (connect) { kernResult = IOConnectMethodStructureIStructureO(connect, // connection handle returned from IOServiceOpen(). kCoreDoRead, // an index to the function in the kernel. structSizeIn, // the number of scalar parameters. &structSizeOut, &sampleStructIn, &sampleStructOut ); } return kernResult; } /***************User client **************************/ getTargetAndMethodForIndex(IOService ** target, UInt32 index) { { // kCoreDoRead NULL, (IOMethod) &com_CoreSnap_UserClient::CoreSnapUserClientDoRead, kIOUCStructIStructO, sizeof(MySampleStruct), sizeof(MySampleStruct) }, } IOReturn com_CoreSnap_UserClient::CoreSnapUserClientDoRead(MySampleStruct *InStruct, IOByteCount InStructSize, MySampleStruct *OutStruct, IOByteCount *OutStructSize) { IOMemoryDescriptor *ReadBuffer = NULL; // Constructing memory descriptor for out put structure ReadBuffer = IOMemoryDescriptor::withAddress((vm_address_t) OutStruct->buff, (IOByteCount) OutStruct->size, kIODirectionIn, fTask); if(ReadBuffer) //Created IOMemoryDescriptor for buff Successfully.... { retRead = ReadBuffer->prepare(); IOLog("\n address of prepare buffer = %p\n", retRead); if(retRead == kIOReturnSuccess) { IOLog("\n prepare for buff Succeded....\n"); // mapping the IOMemoryDescriptr buffer retRead = ReadBuffer->map(); if(retRead == kIOReturnSuccess) { IOLog("map successful\n"); // get the provider for our userclient and call driver read routine UCProvider = OSDynamicCast(com_CoreSnap_driver, fProvider); IOLog("\n UCProvider = %p\n", UCProvider); IOStorageCompletion completion; // calling driver read call by passing IOMemoryDescriptor buffer retRead = UCProvider->CoreSnapDriverDoRead(this, 512, ReadBuffer, completion); if(retRead == kIOReturnSuccess) { IOLog("\n CoreSnapDriverDoRead of Driver Succeded...\n"); //return retRead; } }// end of prepare } ReadBuffer->complete(); ReadBuffer->release(); if (kIOReturnSuccess != retRead) { IOLog("%s[%p]::%s - returning err 0x%08x", getName(), this, __FUNCTION__, retRead); } fProvider->release(); return retRead; } /********************************Driver Read routine ***************************/ // kCoreDoRead IOReturn com_CoreSnap_driver::CoreSnapDriverDoRead(IOService* client, UInt64 byteStart, IOMemoryDescriptor * OutBuffer, IOStorageCompletion completion) { IOReturn retDrRead = kIOReturnSuccess; IOByteCount readBytes; IOByteCount requestByteCount = 0; IOReturn status = 0; IOByteCount bufLength = OutBuffer->getLength(); char *myBuff = new char[bufLength]; readBytes = OutBuffer->readBytes(0, myBuff, bufLength); IOLog("com_CoreSnap_driver::read BEFORE **** readBytes = %lu byteStart = %lu \ bufLength = %lu buffer = %s ***\n", (long)readBytes, (long)byteStart, (long)bufLength, myBuff); // Make "filter" changes to the buffer here. IOLog("\n Calling read routine of driver.....\n"); getProvider()->read(client, 0, OutBuffer, completion); IOLog("\n Called read routine of driver.....\n"); IOLog("\n Calling readbytes.......in driver\n"); readBytes = OutBuffer->readBytes(0, myBuff, bufLength); IOLog("com_CoreSnap_driver::***AFTER::readBytes = %lu byteStart = %lu bufLength = %lu buffer = %s \n", (long)readBytes, (long)byteStart, (long)bufLength, myBuff); IOLog("\n Calling complete routine of driver......\n"); getProvider()->complete(completion, status, requestByteCount); IOLog("\n Called complete routine of driver......\n"); delete[] myBuff; return retDrRead; } We are able to prepare() and map() IOMemoryDescriptor successfully and pass this buffer to driver's read routine(we also have interchange the prepare and map). My problem is while debugging it prints all the IOLogs before driver's standard read() method, but IOLogs after read() does not get printed in system.logs. Do we need to call withAddress() and prepare() and map() the IOMemoryDescriptor before passing it to standard read() method. Are we following correct steps for reading the buffer from disk and passing it to user space application? Thanks Imran _______________________________________________ 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