milesrout · January 18, 2014 05:18
diff --git a/gistfile1.txt b/gistfile1.txt
 OS Interface:

 It has a layered interface.

 It needs to work on different platforms, such the TR3200, the DCPU-16 and the DCPU-16e. 

 Therefore it needs to split the following up:

 User mode user processes (Layer 4)
 User mode system processes (layer 3)
 Architecture-independent kernel code (layer 2)
 Architecture-specific kernel code (layer 1)

 Standalone object code archives that the kernel can load at runtime are called "extensions" as a whole. 

 The 2-1 interface is called the "driver interface", and level 1 extensions are called "drivers".
 The 2-2 interface is called the "module interface", and level 2 extensions are called "modules".
 The 2-3 interface is called the "service interface", and level 3 extensions are called "services".

 Drivers and modules run in kernel mode. Services run in user mode.
 Drivers are architecture-specific. Modules and services are architecture-independent.

 Drivers are architecture-specific extensions that run in kernel mode.
 Modules are architecture-independent extensions that run in kernel mode.
 Services are architecture-independent extensions that run in user mode.

 You would write a driver over a module when you need access to hardware and/or architecture-specific facilities.
 You would write a module over a driver when your extension has general applicability over multiple architectures.
 You would write a module over a service for performance reasons, or because you must do something privileged to the kernel.
 You would write a service over a module if some context switching won't hurt performance too badly, performance isn't critical, and you want the security of being unable to crash the system.
	OS Interface:

	It has a layered interface.

	It needs to work on different platforms, such the TR3200, the DCPU-16 and the DCPU-16e.

	Therefore it needs to split the following up:

	User mode user processes (Layer 4)
	User mode system processes (layer 3)
	Architecture-independent kernel code (layer 2)
	Architecture-specific kernel code (layer 1)

	Standalone object code archives that the kernel can load at runtime are called "extensions" as a whole.

	The 2-1 interface is called the "driver interface", and level 1 extensions are called "drivers".
	The 2-2 interface is called the "module interface", and level 2 extensions are called "modules".
	The 2-3 interface is called the "service interface", and level 3 extensions are called "services".

	Drivers and modules run in kernel mode. Services run in user mode.
	Drivers are architecture-specific. Modules and services are architecture-independent.

	Drivers are architecture-specific extensions that run in kernel mode.
	Modules are architecture-independent extensions that run in kernel mode.
	Services are architecture-independent extensions that run in user mode.

	You would write a driver over a module when you need access to hardware and/or architecture-specific facilities.
	You would write a module over a driver when your extension has general applicability over multiple architectures.
	You would write a module over a service for performance reasons, or because you must do something privileged to the kernel.
	You would write a service over a module if some context switching won't hurt performance too badly, performance isn't critical, and you want the security of being unable to crash the system.