🚀 go-pugleaf

Maynard Handley  <maynardh@apple.com> wrote:
>The major problem is the same reason why protected memory cannot be 
>installed right away. In the past the easiest (or only) way to achieve 
>certain things was to fiddle with certain global data structures. As 
>anyone who knows OS's will tell you, in a pre-emptive environment such 
>accesses have to be atomic, usually surrounded by mutexes. Needless to 
>say the current mac apps do not use mutexes because their access was in 
>the past automatically atomic, by virtue of there being no 
>pre-emptiveness. 

What's wrong with giving each application its own copy of the globals?
The application can then fiddle with them at will, and any system call
whose function depends on them can check the application's copy when
the system call is issued.  You can use the MMU to make this efficient
(e.g., if the dirty bit is not set for any page containing an application's
virtual system globals, then the application has not written to any of
them).

>So what does this mean?

From what I've read, it means that Apple is reinventing for Copland
technology they had already perfected in A/UX years ago.

--Tim Smith