We are using a very simple initializer for the Marvell bridge then
bootstrapping NetBSD from FLASH. That minimally configured kernel
just knows about the disk drive, and mounts it, loads the real run time
kernel and that is the end.

So, the initializer lives in low RAM. The kernel we use as the boot
loader runs in high RAM, and the kernel it loads to disk lives in low
RAM. It works quite well. We also keep a rescue kernel in FLASH
so that if we have disk problems, we can boot the rescue kernel and
do disk and network operations from there. The whole thing fits in
eight Megabytes of FLASH.

Just a thought....

-- 
Douglas Fraser
dwfraser@onebox.com



-----Original Message-----
From:     Allen Briggs <briggs@netbsd.org>
Sent:     Mon, 3 Oct 2005 17:07:27 -0400
To:       Sam Pham <anhmn@yahoo.com>
Cc:       port-powerpc@netbsd.org
Subject:  Re: boot NetBSD using u-boot

On Mon, Oct 03, 2005 at 01:48:50PM -0700, Sam Pham wrote:
> I'd like to port NetBSD on the mpc8540eval board,
> which has u-boot on it.  My understanding is that
> u-boot needs the stage 2 NetBSD loader to boot NetBSD.

That seems to be what it wants, but you can also just download
kernel code and jump to it ('tftp' and 'go').

The stage 2 loader usually lives in arch/<plat>/stand/...
and is different for each system because it's kind of a
bridge between the kernel and the host system.  It might
have knowledge of devices and filesystem formats that the
host system's ROM (u-boot, in your case) doesn't.

It's not clear to me why the 'stage 2 loader' that uboot
expects couldn't be a kernel for development.  A stage 2
loader would be really nice for being able to store the
kernel on, say, a SATA controller on PCI or some such,
but for development, you're probably just downloading
with an ICE or via tftp.

-allen

-- 
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