What is memory protection and why is it so hard to implement for the AmigaOS?

[stefcep2]

Back in the day, AmigaOs 3.x lacking memory protection was acknowledged,  Theoretically, a lot of bad things COULD and on occasion DID happen without MP ie loss of data, OS being crashed by some rogue process.  In reality, few users actually experienced the bad things about not having MP.  Programmers (by good programming practices) and users (by saving often) learned to live without MP. Afterall, many fantastic apps, games, art, music, videos, were created on this OS without memory protection-look at aminet for  proof of that.

The real threats of compromised security and having your computer taken over remotely, or having malware corrupt your OS are likely to come from taking your Amiga online and a third party executing ( 68k or PPC) commands/code with malicous intent.  Yes it IS possible, theoretically, but REALLY how likely is that?  I've heard people say "security by obscurity is no security".  Theoretically no.  In practice when was the last time your amiga got a virus, or had malicous code run on it?  In fact, billions of users have a much higher probability of having  exactly that happen to them, and millions of PC's are running malware at this very minute, and they're all using an OS that has had MP for a decade or so.  I have a feeling this is the point Amiga_nutta was trying o make.

I'd argue, that as a single-user computer, MP on the Amiga hasn't been missed by the users.  MP on the amiga is a more or less academic discussion that interests the (few) developers every now and then. IF you want to run legacy 68k software, hell even PPC software, then  do it like we always have.  Really.  Just remember to save regularly.

[stefcep2]

I would quickly argue against this point at the very least for security sake.

Against what, exactly?

[stefcep2]

I wouldn't let any Amiga powered on for weeks with lots of software running and important data unsaved. This isn't an academic discussion...

I wouldn't mind letting powered on MacOSX, Win2K+, Unix opened with lots of important stuff unsaved. Cause unless there was a powercut I know my data would be back when I'll get back.

I don't want to have to choose the software I run because it may make me lose my work... nor do I want to wait before my HD led is off before powering my computer off, nor do I want to have to check I have enough graphics memory before running a (graphics) memory hungry software because the OS isn't capable of swapping: this is the task of the OS, not mine. The OS should (and will) take down any application trying to write outside its memory mapped, the OS should close all apps and power the computer down when no app is writing to the disk, and the OS should automatically swap memory for my apps...

I think you're overstating the real world significance of these things.

This was acceptable 15 years ago. I think it's not today. Much like monotasking OS isn't acceptable, even for a phone... Would you use some DOS-like monotasking OS today ? don't you think having a GUI or not is an academic discussion ? after all you can do everything you want with just a simple console, right ?

Actually I've never used a single tasking OS.  Started on the Amiga and moved on to Win98SE-which crashed at least as much as my Amiga, suffered much more malware issues, but it did have MP, I suppose.

I don't think the CLI vs GUI argument is the same thing.

I understand the MP is A Good Thing.  Really I do, and I would rather have it than not.

But the REALITY is that millions of users for decades used AmigaOs 3.x without MP to develop god knows how many, apps, tools, utilitities  that didn't bring the OS down, or if they did it was rare, even when dozens ran at the same time.  Then look at the volume of  art, animation, music, video, DTP that was actually created which could not have happened if the apps kept crashing the OS.  And you can STILL do that with the same hardware and software today without MP.  So how much of a hindrance was the absence of MP in practice?  

Personally I think you're overstating the way users were on tenderhooks just waiting for the next imminent crash. It really didn't happen that way.  Most of the time.

[stefcep2]

Nonsense, many users left Amiga due to lack of MP when Internet became "the thing" to do with computers in early/mid 90ies - the lack of MP was also a major reason why Amiga users went on to create Linux and NetBSD for Amiga computers back then.

Many users left coz they couldn't play Doom.  At a user group we used to get 500-600 show up, and I honestly can't recall ANYONE saying, "I'm leaving Amiga beacsue it doesn't have MP."  

I can recall a pirate acquaintance (they always had the high spec hardware) with a warp engine A4000 downloading, uploading, IRC'ing, browsing burning on 3 burners in a scsi box, all the while connected through his 56 k modem, running a monster DOpus config, MCP and a host of hacks, cracks and kludges.  The thing was up for months at a time.   Don't think he missed the lack of MP, like most people.

And as for abusing Amigas online, I know that _I_ have "broken" into remote Amigas that due to malconfiguration and lack of MP meant a lot of fun for me, and maybe not so much fun for someone else.  The highlight was to dump prefs files into remote ENV: and watch the confused target rave about his problems on IRC :laughing:

No doubt it happened.  But 1.  How often and 2.  If I look at the patches released for Windows and internet software eg web browsers that runs on Windows that aim to patch another hole "where a remote user can access/add/change files on your computer", it would seem that the same risks are still there even with MP.  Oh and similar patches are being released for Linux and Linux internet software.

[stefcep2]

Im pretty sure people left because Commodore went bankrupt in early 94.

I think a lot did.  I remember all these souped Amiga's suddenly going for bargain prices in The Trading Post when Commodore went broke.  

What is surprising is that so many stuck around for so long afterwards.