Raspberry Pi questions

Oleksandr Tymoshenko gonzo at bluezbox.com
Tue Dec 25 20:37:36 UTC 2012

On 2012-12-25, at 12:21 PM, Ian Lepore <freebsd at damnhippie.dyndns.org> wrote:

> I got my RPi running this morning, more or less.  I used the boot
> partition from the latest image at http://www.peach.ne.jp/archives/rpi/
> but I'm loading my own custom built kernel and world.  I have a few
> questions...
> Can I get ubldr to load a kernel using tftp, bootp, etc?  

    Yes. ubldr checks U-Boot devices (SD and net), then tries to locate
FFS partition on SD card and if fails - falls back to NFS/bootp. You can fetch
my image, boot partition there contains ubldr, FDT blob, config.txt and boot scripts:


> Are there any
> docs on ubldr in general?  (Right now I'm skipping ubldr and using
> u-boot's DHCP command to load the kernel.)
No, there are BSDCan slides by raj@ but as far as I know that's the only bit of 
documentation for ubldr.

> My RPi comes up with a random ethernet mac address on every boot, but
> when I look at the driver code it seems that there should be an address
> stored in an eeprom.  Do I have to program that myself?
    SMSC might or might not have EEPROM. The one in RPI does not
have EEPROM so it's driver responsibility to set MAC address. There are two
options: get it from FDT blob or generate random. On Raspberry Pi it works like this:
firmware loads FDT blob at fixed address, fixes up board-specific info like memory sizes,
MAC address, board serial/revision. Then it loads u-boot, u-boot loads ubldr, ubldr
generates kernel meta-data, loads kernel and passes control to the kernel. 
Kernel gets FDT blob from meta-data and uses it to determine MAC address.
In order to make ubldr recognize FDT blob you'll need  "fdt addr 0x100" in /boot/loader.rc
either on SD card FFS partition or on your NFS root. 

> When I try to use an nfs-mounted root I get "Mounting from
> nfs: failed with error 19." but if I mount root from
> the sdcard then after it gets to multiuser mode I can manually nfs-mount
> the same directory.  Has anybody got an nfs-mounted root working?
    This is most likely due to NFS version mismatch. We have nfs and oldnfs
for NFSv4 and NFSv3.  I have working NFS root for raspberry pi. My kernel config:

options        NFSCL                   #Network Filesystem Client 
options        NFS_ROOT                #NFS usable as /, requires NFSCLIENT
options        BOOTP_NFSROOT
options        BOOTP_COMPAT
options        BOOTP
options        BOOTP_NFSV3
options        BOOTP_WIRED_TO=ue0

I use FreeBSD 9.0 as NFS server. 

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