[U-Boot-Users] Sequence of Xilinx ML403/PPC
peter.ryser at xilinx.com
Tue Jan 31 07:10:17 CET 2006
Is there any reason why you don't start U-Boot directly out of Flash
instead of using the initial SREC bootloader?
BTW: you can find a snapshot of U-Boot with board support for ML300,
ML310, ML403 and ML410 at
The snapshot contains the patches that have been submitted to this
mailing list back in September of last year. For ML403 just use
$ make ml403_config
to build U-Boot.
S. Egbert wrote:
>Awesome... Got U-boot 1.1.4 working on a Xilinx ML403 (PPC 405)
>evaluation board with our custom core.
>Next for this planning stage, I'm trying to juggle 'leap-frogging'
>memory mapping between the first-loader (Xilinx SREC bootloader in
>firmware), second loader (U-boot 1.1.4) and Linux 2.4 OS.
>Firstly, we started with Xilinx's SREC (bootloader.c) bootloader (I
>know, I know, SREC is space consuming) and plan to replace this first
>bootloader with an ELF or pseudo-binary version later after
>everything-else is checked out.
>Planning-wise, I envisioned that such a bring-up memory overlaying
>sequence would be something like this:
>1. Xilinx bootloader.c reads SREC from 16-bit flash and
>decode/verify/copies to lowest RAM (0000_0000). Then transfers control
>2. U-boot starts up and relocate itself to MONITOR region which is in
>the highest RAM region of 01F0_0000.
>3. U-boot Scripting occurs which copies Linux OS from flash into where?
> Next highest or lowest portion of RAM? Is it dependent on whether
>dual-stage vmlinux.initrd or single-stage vmlinux is used or not?
>At power-up, with U-Boot 1.1.4 being unusually low-RAM-based before
>starting up (instead of executing straight out of ROM), I noticed that
>despite being relocated to MONITOR (higher RAM) region, the PIT
>exception vector appears to be active in 0000_10c0-ish.
>Despite this RAM-to-RAM relocation, this "mtest" clobbering of the
>0000_10C0 region caused Machine Exception error whenever I attempt to
>perform memory test over this supposedly former exception vector region.
> I thought that the objective during U-boot relocation was to ensure a
>completely discontinued RAM region (formerly occupied by U-boot
>A hard and easy questions to the esteemed and avid readers of
>u-boot-users mailing list...
>1. Where do I go from there with regard to the 0000_1000
>(PIT_EXCEPTION). Isn't the PIT specific to Motorola 8xx-series (this
>here is a PPC 405). What exception did the lib_ppc/start.S/trap_init()
>exactly skipped? Skipped an exception mentioned vaguely in this source
>code vaguely. Do I need to tweak the trap_init() some more to relocate
>these untransfered exception vectors into the high MONITOR region?
>2. And lastly, do I go high or low for Linux OS?
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