[OpenBIOS] [commit] r832 - in trunk/openbios-devel: arch/sparc32 drivers

[Tarl Neustaedter]

  On 2010-8-8 2:24 PM, Blue Swirl wrote:
> [...]
> The problem is that some images don't have a bootable partition in
> 'd', but 'a', any of these fail because only the first device is
> attempted in boot-device list. The automagic partition change hack may
> mask this.
>
> [...]
> In the NetBSD case, 'a' is not bootable but 'd' is. Aurora 1.0, Zoot
> (Red Hat Linux 4.0) and SuSE 7.3 only boot from 'a'. In some images
> (for example Debian 4.0R5) 'a' and 'd' are equivalent

Some history behind the boot partitions - if you look at the man page for 
mkisofs, under the -sparc-boot switch, you'll see the various partitions which 
were reserved for particular architectures. My recollection is that partition 
":d" was for the "dragon" architecture, from about 15-20 years ago. The 
current generation of SPARCs use partition ":f" (and have for at least a 
decade), although we may be changing that to ":a" fairly soon.

Current Sun/Oracle release DVDs are created such that all eight partitions 
point to the same physical blocks. You can boot from any of ":a" through ":h", 
and Openboot will be equally happy.

Solaris itself isn't quite as flexible. The common label parsing code does a 
bunch of geometry checks on the partitions, and unless it identifies the disk 
as a read-only removable media, will completely discard the label and return a 
"default" VTOC where only partitions 0 and 2 (:a and :c) exist, and they 
occupy the entire disk. This will matter to you only if you get pretty far 
into booting Solaris.