Process A is running under Linux with mmap -> A
RTL decides to run RT user space process B: RTL must switch the MM
1) much greater overhead in RT switch
2) RT must synchronize access to the MM hardware with Linux.
On the x86, at first glance, the only really critical change is the cr
register pointing at the directory page. But I'm nervous about that
second glance (or 30th), and certainly PPC has a more complex switching
operation .... RTLinux works because it is a fundamentally simple
system, I'm nervous about breaking that.
> So if a hard-RT user-space process suddenly takes a page fault, the
> CPU switches to kernel mode (still running under the RTLinux
> scheduler), and the first thing we do is call rtl_drop_rt(). Same for
> all other kernel entry points.
Yes, I agree that that is how it might should happen.
-- --------------------------------------------------------- Victor Yodaiken FSMLabs: www.fsmlabs.com www.rtlinux.com FSMLabs is a servicemark and a service of VJY Associates L.L.C, New Mexico.
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