Re: NetBSD without MMU ?
[email protected] (Greg A. Woods)
| Newsgroups | gmane.os.netbsd.devel.ports |
|---|---|
| Organization | Planix, Inc.; Toronto, Ontario; Canada |
| Message-ID | <[email protected]> |
[ On Friday, April 12, 2002 at 12:02:17 (-0400), Todd Vierling wrote: ] > Subject: Re: NetBSD without MMU ? > > It's still evil from a modern CPU standpoint. 8-) Maybe evil for modern CPUs with MMUs, but my limited understanding of some of those MMU-less CPUs we might be talking about here are much more ammenable to running position independent code (eg. the 8088 in the way MINIX uses it! ;-).... You can also use a relocating loader in the kernel instead, of course, though unless your coding model is extremely restricted that'll prevent you from moving the process (i.e. doing compaction) once it's been loaded. (Obviously there's still a whole "new" (or rather very old) approach needed for memory management, and processes can't grow beyond some fixed size that's allocated for them on exec, but isn't that what makes programming such "embedded systems" so much more fun and interesting? :-) I think the real win for using a full MMU with hardware page protection support even for an embedded system is of course the benefits of that protection support. -- Greg A. Woods +1 416 218-0098; <[email protected]>; <[email protected]>; <[email protected]> Planix, Inc. <[email protected]>; VE3TCP; Secrets of the Weird <[email protected]>