Re: Using memory above TOS

markt@harlequin.co.uk (Mark Tillotson)
29 May 1996 21:04:05 -0400

          From comp.compilers
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Re: Using memory above TOS markt@harlequin.co.uk (1996-05-29)
Re: Using memory above TOS markt@harlequin.co.uk (1996-05-29)
| List of all articles for this month |
From: markt@harlequin.co.uk (Mark Tillotson)
Newsgroups: comp.arch,comp.compilers
Date: 29 May 1996 21:04:05 -0400
Organization: Harlequin Limited, Cambridge, England
References: <3179B05D.2781@cs.princeton.edu> 96-05-012 96-05-100 96-05-105 96-05-132
Keywords: architecture

> P.S. -- Actually, now that I think about it, the main reason I
> avoided memory above TOS is that I wasn't sure that UNIX
> promised to keep pages above TOS backed up in VM; i.e., if TOS
> was sitting at a page boundary, the page above might be paged
> out at an arbitrary time, and then be reallocated zero-filled
> when next referenced, losing the contents of words above TOS.


I've never heard of that - the pager isn't going to check which
user-mode register was responsible for generating a virtual address,
it will just deal with the fault and restart the instruction. You
certainly wouldn't be able to implement thread-libraries if the kernel
looked at the stack pointer!!


__Mark
[ markt@harlequin.co.uk | http://www.harlequin.co.uk/ | +44 1223 873829 ]
[ homepage http://www.hal.com/services/juggle/home/markt@harlequin.co.uk/ ]




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