site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com On Jan 9, 2007, at 7:40 PM, Greg wrote: On Jan 9, 2007, at 8:32 PM, Michael Smith wrote: typedef struct { unsigned char buffer[256]; unsigned char bufferSize; } MyIOUserClientArg; = Mike _______________________________________________ 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... Also, as I asked in the other email, can you pass a pointer to a user-land allocated buffer as a parameter to a method call for the kernel to use? You can, although the kernel can't access it directly. As I pointed out previously, if the data is small (you mentioned 50 bytes, which is very small) you're better off just copying it. If you need to pass it to hardware, or to map it, you need to construct an IOMemoryDescriptor referencing it. By "just copying it" do you mean, as Brian pointed out, passing a structure of this sort: Yes, although I would put the size member at the front of the structure so that you don't waste another cache line accessing it. This email sent to site_archiver@lists.apple.com