Re: Ultra10 problems with -current

[Eduardo Horvath <eeh%NetBSD.org@localhost>]

On Wed, 2 Nov 2011, Martin Husemann wrote:

> On Tue, Nov 01, 2011 at 07:36:19PM -0400, Michael wrote:
> > Isn't there some restriction, like all / must be in the first 4GB or so for 
> > OF's disk read methods to work properly?
> 
> Yes, but I never found a good documentation (limits vs. OF versions)
> that matches practical experience in this area.

Let's see what I remember about this...

OpenFirmware's seek method takes 2 32bit cells for the byte offset into a 
device, so that interface is not the limitation.

For SCSI drives some versions of OBP are limited to READ(6) or READ(10) 
commands.  READ(6) is limited to 16 bit block numbers or 33MB bytes.  
READ(10) is limited to 32 bit block numbers or about 2T.  

For IDE drives it probably tries to use CHS mode rather than LBA 
addressing, sot it varies based on what the disk advertizes as its 
geometry.  In theory you can have 8 bit sector x 16 bit cylindere x 8 bits 
x 512 byt blocks head for 8GB of storage.  In LBA mode you have 27 bits of 
addressing for 137GB max size, but I wouldn't guarantee that older 
versions of OBP support that.  

A U10 has IDE drives so you are suffering from whatever the limitations 
are on your IDE drive.

Eduardo