Booting YDL 2.1 on B&W G3 Problems

[Timothy A. Seufert]

At 11:38 AM -0400 6/29/02, Bill Fink wrote:

>Here are some of my experiences with installing Linux on a B&W G3 at work.
>First, it just would not install on the slave drive, so I had to switch
>master and slave.  It is my understanding that early B&W G3s cannot boot
>from a slave drive because of an OpenFirmware bug.

Hmmm... I'm fairly sure I've booted a B&W from a slave drive at one 
time or another.  I do remember not being able to do a plug & chug 
install of Linux to a slave, due to bugs in the installer.  (I forget 
which distribution and which version of it.)

BTW, Apple has a firmware update for B&W G3s, so if you have apparent 
OF bugs, apply it.  It applies both to rev 1 and rev 2 B&W G3 systems.

http://docs.info.apple.com/article.html?artnum=58374

>But even after installing Linux on the now master drive, I was still
>having all kinds of problems actually running Linux on that system
>including weird system errors and file system corruption.  These finally
>went away went I installed a custom built 2.4.19-pre8-ben0 kernel.
>
>However, I noticed that Linux wasn't detecting the original (now slave)
>internal disk drive.  I tracked this down to not having the CMD64X driver
>configured in my kernel and added it in.  Linux then detected the slave
>drive, but unfortunately the weird system errors and file system
>corruption also returned.  I also checked and determined that the
>default YDL 2.1 2.4.10-12a kernel has the CMD64X driver enabled,
>which explained the earlier problem behavior.  It is my understanding
>that some of the early disks in the B&W G3s had buggy firmware, so I
>got bit by two early B&W G3 bugs.

I haven't heard of any disk firmware bugs before.  I think what you 
got bitten by is the known IDE chip bug.  The B&W originally shipped 
with rev 5 of the CMD646U2 controller.  Rev 5 has nasty corruption 
problems in UDMA mode in master/slave configurations.  Even with only 
a single drive attached, it can have problems (depends on the drive 
model -- some work fine, others don't, the only ones you can trust 
for absolute sure are the factory original drives which Apple did 
qualification testing on).

The reason you aren't having problems when you eliminate the CMD64X 
driver is presumably that the generic IDE driver can't enable UDMA 
mode.  It might not even be able to enable DMA.

Anyways, CMD fixed the problems in rev 7 of the chip, which Apple 
incorporated into Rev 2 of the B&W motherboard.  As far as I have 
ever been able to tell, that was the lone motherboard change during 
the product life of the B&W G3, which is pretty unusual and means 
that it was a solid design aside from the use of a buggy IDE chip.

How you can tell what you've got: Rev 7 chips are marked 
"CMD646U2-402", while Rev 5's lack the "-402".  The chip is located 
in a far corner of the motherboard, behind the PCI slots (between the 
slots and the slot covers).  Fortunately, it's on the top of the 
board, so you don't have to take the board out.

If you're in Linux, you can find the chip revision without cracking 
the box.  Just issue the "lspci" command and look at the revision 
given for the 646.

-- 
Tim Seufert