On Fri, 27 Oct 2000, Bob Nestor wrote:

> This is the dump I got from the MacOS X CD.  Looks like it's like other 
> Apple CDs I've looked at in that some of the fields aren't exactly what 
> they should be - disk size for instance. Map Entries #4 and #8 are 
> different; I haven't seen anything like that before.  It looks to me like 
> the CD is relying on the Start Manager to get booted?  As I understand it 
> this means the ROM (or OF) is looking for the HFS partition marked 
> bootable and loading something that it thinks is MacOS from that 
> partition.  Does anyone know if this would load and execute NetBSD if it 
> appeared to be in the proper place in an HFS partition?

Part of what's going on is that you're supposed to use native block sizes
when making Apple partition maps. Thus on a CD, you're supposed to use 2 K
blocks, not 512-byte blocks. But lots of tools, like the one you used,
only know about 512-byte blocks. So the "canonical" think to do (from what
I've gathered) is to make one partition map with 512-byte blocks, and
another with 2K byte blocks. Entries #4 and #8 are common to both maps, so
they are "void" to keep the maps from getting quite confused.

> Partition map (with 512 byte blocks) on '/dev/ata0.0' (/dev/hda)
>   sbSig:       0x4552    sbBlkSize:  0x0800    sbBlkCount:  0x00050000
                                         ^^^^ Not 0x0100 :-)
>   sbDevType:   0x0001    sbDevId:    0x0001    sbData:      0x00000000
>   sbDrvrCount: 0x0004
>     [1]  ddBlock: 0x00000010   ddSize:  0x0005   ddType:  0x0001
>     [2]  ddBlock: 0x0000001e   ddSize:  0x0019   ddType:  0xffff
>     [3]  ddBlock: 0x0000003c   ddSize:  0x0005   ddType:  0x0701
>     [4]  ddBlock: 0x0000004a   ddSize:  0x001d   ddType:  0xf8ff

> Partition Map Entry #4
>   pmSig:        0x504d      pmSigPad:      0x0000
>   pmMapBlkCnt:  0x0000000a  pmPyPartStart: 0x00000000 pmPartBlkCnt: 
> 0x00000000
>   pmPartName:   
>   pmParType:    Apple_Void *** Non-standard ParType ***
>   pmLgDataStart:0x00000000  pmDataCnt:     0x00000000 pmPartStatus: 
> 0x00000000
>     (not valid, available, free, not bootable, not readable, not 
> writable, non-PIC boot)
>   pmLgBootStart:0x00000000  pmBootSize:    0x00000000 pmBootAddr:   
> 0x00000000
>   pmBootAddr2:  0x00000000  pmBootEntry:   0x00000000 pmBootEntry2: 
> 0x00000000
>   pmBootCksum:  0x00000000  pmProcessor:   
>     *Error* - Partition not adjacent to previous partition
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^

Since when is this an error??? :-)

Take care,

Bill