In article <20020321190824.J508-100000@furtle.home>,
   James Holtom <jholtom@furtle.org> wrote:
> I used !HForm (2.52 01 Dec 1999) and allowed it to use longfilenames.
> HForm says the disc is 16383/16/63 C/H/S, but with LBA revises this to
> 29795/16/63. I formatted the RISC OS partition as 13315 cylinders.
> Unfortunately bb_netbsd thinks I've got -3328 cylinders running from 0
> to -3329... argh... I haven't let it proceed to mash my disc...
 
My quick calculation says that the RISC OS partition is of the order
of six gigabytes in size.
 
> I am wondering if:
> a) the disc is too big for it
> b) the 'longfilenames' option I selected has used a whacky format, the
> bootblock for-which is not understood by bb_netbsd, or worse is not at
> 0xC00 ...
 
The problem is that bb_riscbsd cannot handle properly the case
where the RISC OS partition is greater than four gigabytes in
size. Looking at the code, I *think* it will work correctly if the
RISC OS partition size exceeds this, but you try this at your own
risk. All bb_riscbsd does is set up a pointer in the boot block of
the disk to the NetBSD partition. This is just a cylinder number,
the value you enter. There is a sanity check to make sure this
cylinder number does not lie in the RISC OS portion of the disk,
but this test goes wrong if the RISC OS partition size exceeds the
four gigabyte mark. (Actually, it treats the size as signed
quantity so it goes wrong if it exceeds two gigabytes.) This is
not a trivial fix as it will be necessary to change the RISC OS
SWIs used by the code to find the disk size and then to test it to
destruction. 
 
I noticed this a while back. I guess I ought to open a pr for it.
  
> Can someone tell me what to do / reassure me 'it will just work'...?
 
See above. As I said,I *think* it will work correctly but you try
it at your own risk.
 
> I note from the archives that there were issues with the bootloader, but
> I haven't got that far yet, and didn't see anything about disc
> partitioning :-(
    
Bootloader issues have largely been resolved. However, there are
several bootloaders in circulation now. Versions of the updated
original bootloader work with RISC OS 4 and RISC OS Select, but
there is a problem if your machine appears to have more than four
blocks of physical memory in it (which is what can happen with
RISC OS Select). You will need the 'memfix' module if you have RISC
OS 4.03, but this should be included with the bootloader now and
dealt with automatically.
  
Dave Daniels