Amiga OS4 on old (PPC) Macs

[HenryCase]

Hans wrote:
DRM code in UBoot? I doubt it. That would be the silliest place to put copy protection as replacing the bios would eliminate it. I'm not even sure if there is any DRM code in OS4; the A1 or classic Amiga hardware are dongles enough as-is.

Fair point.

Hans wrote:
I doubt that analysing UBoot would give you much knowledge about OS4 as it only affects the bootloader that copies the Kernel modules into RAM. I doubt that it would be too hard to write an alternative bootloader; the second-level booter basically searches for a kickstart directory and loads the modules as per instructions in the kicklayout file.

The real issue remains the drivers, and the fact that the HAL is compiled right into the kernel. It would make more sense to decompile the Loader module, and the kernel. Someone who could isolate the HAL code sections would be able to create a patch in such a way that the patch code contains no copyrighted IP. Replacing the HAL is a sizeable task.

I thought the BIOS would give us some clues about how the drivers worked, didn't realise the HAL (HAL = Hardware Abstraction Layer, right?) was purely run through software.

Hans, can you explain how the A1 version of OS4 boots (from your understanding of the matter)? I have never seen an A1 booting so my knowledge is limited. Does the system perform a POST?

Taking the display driver as an example, does the BIOS have to load the software kernel before anything is displayed on screen, or can you, like on x86 PCs, bring up BIOS settings on screen before the main OS starts?

motorollin wrote:
Well legal or not, I'm now convinced that this works. Having had another suggestion from AmigaMac, I got my copy of the OS4 boot CD to boot on my Mac Mini and get as far as launching ExecSG, and then it just went to a black screen.

That's awesome. You're not the only one to have some success here either:
http://moobunny.dreamhosters.com/cgi/mbmessage.pl/amiga/152833.shtml

Colani1200 wrote:
Did you try this with the OS 4 classic CD? I read somewhere that the A1 version is needed, maybe that is the problem.

The versions of OS4 released so far are meant to be similar, but I agree that the A1 version is more likely to be successful, as the h/w for MacMini is closer to A1 h/w than CSPPC/BPPC h/w. Also, if these are the leaked Project Moana files it would have been developed with A1 OS4 as Classic OS4 wasn't as complete at the time the Moana announcement was made.

[Zac67]

Is AmigaMac's boot CD a hoax or not? Just got a PowerMac 9500 for peanuts, a Crescendo G4/1GHz is only $99 for it.
Does this actually work?? Can anyone send me the file?

[DBAlex]

Well, Guess What...

The thing friggin boots to the OS4 Kernel doesn't it!

 :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o

Thats using the 1st option on the CD... the other options don't work as well, although I can get to the early boot screen by holding down both mouse buttons and all my hardware is detected... More to come w/ pictures and videos (is that legal?)

 :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o  :-o

Its amazing though! :-)

I can't get to load the workbench or anything, is that right or not?

I can only access the early boot menu if I use option 4 or 5 in the boot options (shown in the screenshot)...

Its amazing though!
 :-D

[Hans_]

HenryCase wrote:
I thought the BIOS would give us some clues about how the drivers worked, didn't realise the HAL (HAL = Hardware Abstraction Layer, right?) was purely run through software.

Hans, can you explain how the A1 version of OS4 boots (from your understanding of the matter)? I have never seen an A1 booting so my knowledge is limited. Does the system perform a POST?

UBoot looks a lot like a PC bios. It has an x86 emulator so that it can use the VGA-bios to display text/menus. After power-on tests it searches for a hard-drive with a Second-Level Booter (SLB). You can configure UBoot to boot via other methods too, e.g., via TFTP. The second-level booter scans the hard-drive for a partition containing Amiga OS4, and for Linux boot directories containing a boot.conf (or is that a1boot.conf? I can't remember). The user can select whatever configuration he/she wishes to boot. If OS4 is selected, the SLB loads the kickstart modules into RAM and starts ExecSG and UBoot drops out of the picture. The kickstart modules must include all the drivers for the essential hardware components (i.e., the IDE drivers, VGA drivers, northbridge, etc.). Holding down both mouse buttons at this point brings up the Amiga Boot menu that people are used to from Amiga OS 2.0 and up.

This is my basic understanding of the boot process on my A1.  Note that I've never seen any code, nor tried to analyse the process in any detail. I think that loading the kickstart into memory would be the easiest thing to do if you were porting OS4, and the OS4 developers have said that different BIOSes are fairly trivial to adapt to. The HAL, on the other hand, must be adapted to whatever particular PowerPC variant is being used.

Hans

[kickstart]

Hi.

I reading something about it in anothe amiga forum and i cant believe the poor explanations or docs of this loader for macmini ppc, its true or hoax?

If its true, why make a loader only for a certain model of macmini ppc?

I own a macmini g4 1,42ghz 32mb radeon and this loader dont work here.

[DBAlex]

It works, trust me, I just can't release any information at the moment.

I have it booting to the OS4 Kernel screen here on a 1.5ghz with 64mb Radeon 9200 Mac Mini.

Alex.

[spihunter]

interesting.... Maybe the 1.5ghz G4 64MB Radeon is the "special" Mini it was made for?

[kickstart]

Ok i trust you, but why this secretism?

1,5ghz 64mb radeon or the openfirmware are a minor update just for not run another OS, exist another version of this loader for different versions of openfirmware?

[skurk]

Bloody hell, now you guys got me going.

Alex, let's hear/see it (and if you need images/videos hosted somewhere, send me a PM)

I have an old PPC Mini gathering dust (can't remember the FW version ATM).  I'd love to give this a go, too.

[motorollin]

Just watched Alex's video. This definitely works.

--
moto

[AeroMan]

Where's the video Where's the video
I'm getting anxious... This would close 2007 with a golden key

(Should I run to E bay to get my Amiga Mini )

[DBAlex]

 

[HenryCase]

@Hans
Thanks for the info Hans. I am basing my analysis of A1's boot sequence on my limited knowledge of the x86 PC boot sequence. However, one part of your explanation leaves me a little mystified...

If UBoot powers up the system and tests it before handing control to OS4, then it already has the hardware drivers loaded, right (otherwise it would limit the tests it could perform)? If the hardware drivers are loaded by UBoot, why would OS4 then go to the trouble of loading them again? If your description is accurate then Hyperion have shot themselves in the foot by not using the most efficient loading method.

@DBAlex
You da man! :-D

[wegster]

OK... Wegster can decide if these stay or not... These are TEMPORARY... They may be removed soon...!
Enjoy! :-D

I think you've got me confused with Wayne...I'm a mod on AW, not A.org :-D

Interesting stuff, nonetheless...

[AeroMan]

Oh my god... AmigaMac reached the Holy Grail and was banned from the other forum.
He should be pi**ed...

Does it needs OS4 CDs to boot ? If it does, is the classic version enough or do I need to get an A1 version ?

I thin we're going to have a really happy new year !
 :-D  :-D  :-D  :-D  :-D

[DBAlex]

@AeroMan

Nah, It boots just from the files that AmigaMac released on EAB as long as the Mac Mini firmware version is right [1.5ghz G4 - 64mb Radeon 9200]

I'm going to be trying different things to get more of a "successful" boot in the next couple of days.

What a nice present for the new year, hehe! :-)

 :-D  :-D  :-D