@Offa

http://www.microsoft.com/technet/archive/wfw/7_agloss.mspx

Strict management of system memory to prevent the corruption of any application's program code or data by interference from another application. Memory protection ensures that concurrent applications are compatible and prevents them from interfering with system processes.

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@EntilZha

Quote:

Alright, which API is not MP safe ? One example, please.

There's plenty of examples, just pick a function at random from any of the system libraries that deals with and/or implies message passing or, more importantly, just think of the current possibility, often exploited, to peek and poke from/to any system structures.

AmigaOS lacks abstraction, more often than not you're required to fiddle with structures that are shared by many tasks.

But let's say you implement a way to explicitely protect some memory from being overwritten by some tasks other than the one that allocated that chunk of memory: how do you handle the page fault when another task attempts to write into that zone of memory? You can't go and just shut the culprit task down, you can't even safely lock it until the next reset, and this is because that task may be in charge, temporarily or permanently, of some resources which are shared with other tasks, and over which the OS has no control whatsoever. Real Resource Tracking (as in a non cooperative one) is simply not possible in AmigaOS, as there's no concept of ownership of resources.

Even then, however, the possibility for a, say, filesystem to write-protect its cache buffers and control structures would be a "must have", because even if you would still need to reboot the machine in case of page fault, you'd at least be assured that nothing bad happened to the on-disk data. This is the only useful use of memory protection AmigaOS, as we know it, could have.

Last edited by falemagn on 08-Nov-2005 at 01:19 PM.
Last edited by falemagn on 08-Nov-2005 at 01:17 PM.

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@itix

Definitions are most welcome

I'll add some too

http://www.answers.com/memory%20protection

Computer Desktop Encyclopedia:

Quote:

A technique that prohibits one program from accidentally clobbering another active program. Using various different techniques, a protective boundary is created around the program, and instructions within the program are prohibited from referencing data outside of that boundary...

Wikipedia:

Quote:

Memory protection is a system that prevents one process from corrupting the memory of another process running on the same computer at the same time. It usually employs hardware (i.e. a Memory management unit) and system software to allocate distinct memory to different processes and to handle exceptions arising when a process tries to access memory outside its bounds. There are different ways to achieve memory protection. Segmentation and paging are the most common methods...

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@itix

Quote:

If you wish to have an OS without software that is way to go. Memory protection would break all existing software including OS4 native ones.

That would be just temporary. OS4.0is not offcially released yet, and there is already lots of stuff for it. I don't see any reason why same could not be done for future versions of memoryprotected OS4.x. Every current OS has gone trough major transitional phases when it's API has changed more or less.
Just look at eg. the MacOS X. (ok OSX is not same as original MacOS) Or compare Win XP with Win 3.x. Almost all current operating systems also have somekind of "emulation" for the old legacy software.

You can't really expect AmigaOS API to stay fully OS3.x compatible forever, atleast not if you want to modernize the OS radically.

Ofcourse this speculation is quite useless, only Hyperion knows what their future plans are. I would be happy with OS4 whitout memory protection or with partial/optional memory protection. But if there someday would be full memory protection it would be good thing even if it would mean changes in the API.

Last edited by miksuh on 08-Nov-2005 at 03:40 PM.
Last edited by miksuh on 08-Nov-2005 at 03:35 PM.
Last edited by miksuh on 08-Nov-2005 at 03:25 PM.

@thread

we can use uae!
or whatever, ppl will recompile, dev will follow,
memory protection will grant the god like status to amiga os!!!111


memory protection!!!
look at the poll everyone want it, i want it too!!

@freaks

But recompile doesn't suffice when APIs do change.

As long as our software base is counted in hundreds and the count of REAL native apps is very low, I suggest that we will keep continue to support legacy programs.

Last edited by Mr_Capehill on 08-Nov-2005 at 05:41 PM.

@Mr_Capehill

i disagree. keeping old compatibility will drive us nowhere.
amiga need to evolve a bit.
i want to keep the best:
- user friendly
- hunan understandable os structure and hierarchy (system drawers)
- same usability
- fun to use
- fast, low ressources, bloat free.
- looking awsome ;)

now we need this to be rock stable.
if the API have to mutate a bit, dev will be able to follow,
this isn't the first time.
as long as the spirit is kept, ppl will follow.

when i said "recompile" in my previous post,
of course i didn't meant a simple recompile without any change.
some change in the code are mandatory.
if you look closely, this is already the case for amiga os4.
apps code had to be adapted a bit.


anyway that feature is planned. i'm not the only one who thinks it's important.
i just ague to say it's urgent ;)

@falemagn

Quote:

AmigaOS lacks abstraction, more often than not you're required to fiddle with structures that are shared by many tasks.

Not really true, at least AmigaOS4 has lots of functions to peak and poke the structure on behalf of the program, not every one is going to follow this guide lines, how ever there are guide lines there to follow for the once how are looking.

for example draw-mode JAM1 and JAM2 can be set by OS functions for the window rastport structure.

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@elwood

Hi,

As a user (not a developer) I voted in favor of keeping old programs able to
run. At least one of the programs I use (Scion, for my genealogy) is really
not likely to be updated (or replaced) in any meaningful time interval. It
currently works flawlessly with AOS4, and I sure don't want to lose that. It
is a darned good genealogy program, with many useful ARexx scripts, however
there are very few current Amiga users that are genealogists. Most of the
other software I use could be replaced, but Scion is unlikely.

As to running it using E-UAE, well I still haven't even figured out how to
get E-UAE installed and running properly. I sure could use a good set-up
program, such as Amiga Forever. In addition, I find having to start up an
emulator thoroughly time-consuming and unsatisfactory.

I could accept "optional" memory protection of some sort, allowing me to go
on my merry way without memory protection. That would be okay.

Regards,
Don Feldbruegge

Hi Everyone,


I'm going to speak without knowing what I'm talking about, using only preconceived notions on this subject. (NOTHING new there, huh?)


The way I see things.


AOS worked, AND multi-tasked WITHOUT memory protection, SO, just what is it that we get WITH memory protection besides a whole whack of non-working SW?


Now, to the preconceived notions.

1) I think that memory protection adds to the OS, as in, slows it down.
2) I don't think ANY SW HAS to have memory protection, that we know of. (This is of course, IF the SW writer KNOWS EXACTLY what he is doing.)
3) I think that it is in fact possible to write SW WITHOUT memory protection that can do things that CAN'T be done WITH memory protection in an OS. IOW, I think some unique applications ARE POSSIBLE in what may be the LAST no memory protection OS left.

Can anyone say I'm wrong on all three counts? (I can't think of anything else, but it would be in the same track of thought.)

I voted "NO" to memory protection, as I'm judging from, "AOS works now, and great, I might add."

Hi Everyone,


More concerns.


What is event tracking, it's different to memory protection, right?

Does it slow down the system much?

Can just event tracking be added without breaking any old SW?

Will memory protection keep demos from working, and democoders from doing anything that they could do or get away with in the past? Without knowing the other side of the coin, I'm kind of against it then.

Unless it JUST HAS TO CHANGE, I like the way it was/is just fine!!


BTW: Do embedded systems, PDAs, cell phones, STBs, etc. HAVE TO HAVE memory protection and/or resource tracking?? I could be wrong, but Hyperion don't seem to be concerned.