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Re: PowerPC kernels, partitioning on macppc



James Buchanan wrote:

Hi everyone,

I'm new to the PowerPC platform, and tried to install Sarge netinst this evening. My experience with the printk messages being suppressed during package installation is in another post to debian-powerpc and debian-boot lists.

Can someone tell me what the various partitions are for on the macppc? I couldn't partition the disk without using guided partitioning. The guided partitioning selects a small ~35K partition labelled "Apple" or something, and a NewWorld boot partition of 1MB for yaboot, I think. Why these partitions and why the sizes selected? Is this required for OF or something?

Also when the system starts, it prints the address of the framebuffer. Is this saved into /var/log/messages or anything like that? I would certainly like to learn more about the PPC architecture. Is there a good book on assembly language for the PPC with details of I/O, how to access/discover hardware, how to set up paging with the MMU, etc? Is using OF necessary past the boot stage? Can it be ignored after that as the BIOS is ignored after booting on x86 platforms? Is there any documentation on the Debian port to PowerPC for beginners interested in system level software and kernel development?

Are there reserved memory regions for the PowerPC on the mac? How does the kernel discover how much memory is installed? Perhaps through a call to OF? The kernel seems to be loaded to some arbitrary location, as I've seen somewhere. If this is so, how is the kernel linked? Must it somehow relocate itself?

And how to handle interrupts on the MacPPC, and all that stuff the kernel does... books, docs on the net, etc.

Thanks for your help. :)
James


Well, let me take a stab at this one. I don't think the boot sector on the PPC architecture is the same as that on a PC, in where the MBR is. the "bootstrap" partition IIRC is only 800k and that is what is "blessed" to allow your system to boot linux, using yaboot (New World) don't know about BootX or the other ways of getting into linux. Yaboot looks almost exactly, and from what I understand, acts like The PPC Open Firmware. I am not sure what you mean by "using OF past booting" but if you mean supplying the kernel with ofonly then on most (I guess) it is not. The kernel will take ahold of your Graphic's Card Framebuffer automatically with no kernel argument. If the screen goes blank after the kernel takes ahold, some people (me included) have mistakenly thought the kernel froze. In most cases the "video=ofonly" will alow the kernel to use the OFfb to display video. Not sure about the apple partition, but a mac-fdisk on mine reports three partitions around the size you mention. /dev/hda1 type: Apple_partition_map name: Apple Size 31.5k System: partition map, /dev/hda3 type: Apple_Driver43 name: Macintosh size: 37.0k system: Driver 4.3, /dev/hda5 type: Apple_Driver_ATA name: Macintosh size: 37.0k system: Unknown The Framebuffer printout I am not sure about but I generally see people referring to dmesg for startup stuff, but I have not used this, and don't really know what it's for.
Hope that helps!

--Mike S



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