On Thu, Oct 28, 2010 at 2:56 PM, StephanT <[email protected]>wrote:
> John, > > > I do not plan to argue this further in advance. > > :-) It wasn't in my intention to argue anything. Just knowledge exchange. > Why yes, a very fine line indeed. > > > In a microkernel drivers could have their own global namespace and not > have > >direct access to memory. > > As long as the processor doesn't provide any specific mechanism to protect > the > memory access from itself - I mean here "kernel-mode" - namespace or not > the > code executing in kernel mode will do whatever it wants with the memory. > Even > if the driver has not direct access to memory some other code has to have > it. > The driver will request memory modification via a message. If the request > is > malicious the executing part has no way to know it. Or if it does it means > the > memory management is in kernel mode - and this is no longer a microkernel > ... > > In my opinion the solution is not to isolate the memory access from the > executing code but to provide some protection mechanism in H/W. The MMU > does half this work today. It remains to invent the other half. > > I thought you were aware of such mechanism when I asked you to elaborate... > Sorry if my knowledge was less then expected :) My thinking was that having the insmod command is the same as having /dev/mem in a Linux kernel. I am a constant student of the kernel and after 10 years I realize every year that the more I learn the less I know! The biggest mistake you can make in Linux kernel programming is assuming you already know something. > > Anyhow, thanks for sharing. > > And thank you back... -- John
