PERFORCE change 29745 for review

[Peter Wemm]

John Baldwin wrote:
> 
> On 25-Apr-2003 Peter Wemm wrote:
> > http://perforce.freebsd.org/chv.cgi?CH=29745
> > 
> > Change 29745 by peter at peter_daintree on 2003/04/25 16:01:39
> > 
> >       Add a pcb flag to indicate that a full trapframe restore
> >       is required, even from syscall.. eg: a sigreturn(2).
> >       I'm not sure if this is the right place for it.  mdthread
> >       perhaps?  Anyway, it'll do for now.
> 
> mdthread sounds right.  Alpha uses a flags field on the trapframe to
> accomplish this:
> 
> sys/alpha/include/frame.h
> #define FRAME_FLAGS             27
> #define FRAME_FLAGS_SYSCALL             1 /* partial frame for syscalls */

They put the frames in the space reserved for the 'zero' register if I
recall correctly.

On a side note, there are times when I'd like to move the pcb stuff into
mdthread..

Cheers,
-Peter
--
Peter Wemm - peter at wemm.org; peter at FreeBSD.org; peter at yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5