On Sat, Apr 10, 1999 at 02:13:38PM +0000, Patryk ?ogiewa wrote:
> Napisane 09-Kwi-99 przez: Ignatios Souvatzis...
> 
> >> Does anyone know the exact specifications of the (in)famous 4GB hard drive
> >> limit?
> >> 
> >> AFAIK it is the matter of the number of addressable blocks but what are the
> >> _exact_ limits? Drive size? Partitions size?
> 
> >Several different.
> 
> >For one, the classic IORequest interface can only reach the first
> >4*1024*1024*1024-1 bytes of the drive.
> 
> >As a consequence, partitions containing Amiga bootblocks MUST BE COMPLETELY
> >WITHIN the first 4GB.
> 
> Does that imply that non-bootable (from AmigaOS) partitions _can_ lie above
> that?
> 
> >Other than that, NetBSD can address 4*1024*1024*1024* (fs fragment size) 
> >blocks using BSD FFS partitions.
> 
> You have written "blocks". Thus if the blocksize (aka fs fragment size?) is
> e.g. 1024 bytes - then NetBSD can access 4*(1024^4) i.e. 4096GB. Right?

To be exact: 2^32 * fragment size. NetBSD/AMiga uses 8192/1024 filesystems
per default, so you're right.

> 
> >I won't comment AmigaOS usage here. THere are 2.5 different approaches to
> make
> >AmigaOS work with >4GB drives.
> 
> No. I am not interested in trying any of those 5*0.5 approaches... ;-) I
> simply want to set all my partitions that are to be accessed from AmigaOS
> (including MacHFS, msdos etc.) to lie exactly within the limits and configure
> the rest of the drive for use under NetBSD. I think that this would make my
> life much easier than trying to make AmigaOS use the rest of the drive,
> especially that I need to have NetBSD partitions on it anyway.
> 
> 
> >> Could someone confirm or deny if I am right thinking this way? And give me
> >> clues about the exact limits or at least what exactly causes them so I
> could
> >> calculate them myself.
> 
> >Uhm, you'll damage the disk if you use unmodified HDTOOLBOX with unmodified 
> >drivers on a big disk.
> 
> Even if ALL my AmigaOS accessed partitions will lie within the first 4GB (or
> what exactly the limit is) and above that, there will be only the ones used by
> NetBSD ??? Till now I got no real problems with HDToolbox. The only drawback
> was that it shows the disk/partition size in weird numbers (-2013MB or 15MB
> for example) but seems to store the actual block numbers correctly.

Uhm, you need to create the NetBSD partitions using hdtoolbox or something 
similar. You can use hdtoolbox if you have the newwhatwasit patches from 
Amiga Int.

> 
> >Other than that, your root partition must be below 4GB, so that the ROM can
> >access the bootblock, and the kernel on behalf of the bootblock.
> 
> Understood. I can do it this way: 'root' - within the limits. 'swap' and 'usr'
> above. But this applies only if one wants to boot NetBSD from the bootblock I
> suppose? Otherwise all can be placed above AFAI understand.

right. But why not reserve 50 MB below, and be able to choose the OS from 
the Amiga boot menu? (thats 50 of 4096... not an unreasonable number.)

Regards,
	Ignatios