On 08/29/2012 07:58 PM, Rick Thomas wrote:
On Aug 29, 2012, at 4:25 PM, Rick Thomas wrote:
I just tried booting a PowerMac G4 with the Wheezy installer image
"built on 20120826-03:23" (details of where I downloaded it from,
etc
available on request).
The G4 is a 32-bit machine, but it seems to be offering me the
choices
for a 64 bit machine.
Before the "boot:" prompt it said (among other things)
install 64-bit processor (G5 or POWER3/4/5/6/7)
install32 32-bit processor (G4 or earlier)
and when I entered <tab> at the "boot:" prompt I saw the list of
options
install expert rescue
auto install32 expert32
rescue32 auto32
At this point you can still type: install32
If I just hit <ret> at the "boot:" prompt it looks like it's
trying to
boot the 64-bit kernel, which (of course) fails on the G4.
The only unusual thing about this is that I'm booting from a USB
stick
using Open Firmware, rather than from a physical CD-ROM. Should
that
make any difference?
When you load yaboot binary directly from Open Firmware you are
skipping
blessed stage one boot loader script. That is making the difference.
I just tried booting that installer from a physical CD-ROM on the
G4. I
got the expected (32-bit) messages.
So, I guess booting from a CD sets something in the OF environment
that
isn't being set when booting from a USB stick?
By default, PowerPC Macs boot from a CD/DVD drive by loading an Apple
specific blessed file located in an Apple_HFS partition. The blessed
file is a stage one boot loader. It is a file containing Open Firmware
commands that are figuring out whether they run on 32-bit or 64-bit
machine, followed by a boot command that loads yaboot binary while
passing appropriate arguments to it.
If yaboot binary gets loaded without arguments it will offer both 64-
bit
and 32-bit options, but default to 64-bit.
Is there a fix for this, or is it an un-common enough use-case to
just
need to be documented as a limitation.
The on-screen instructions are correct. Thus, the manual could just
say
something like this: "When the machine boots, follow the on screen
instruction."
Milan