netboot configuration [was: Re: NFS Root with Raspberry Pi (nfs_diskless: no interface)]

[Daniel Braniss]

> On 30 Sep 2015, at 12:58, Daniel Braniss <danny at cs.huji.ac.il> wrote:
> 
> last resort, check hardware
> 
> so I took a brand new rpi, same problems.
> i saw many gpio0: stray interrupts, so I changed power supply, BINGO!

spoken too fast :-(
back to old problems.

> it now works!
> thanks all for your patience.
> cheers,
> 	danny
> 
>> On 30 Sep 2015, at 10:39, Daniel Braniss <danny at cs.huji.ac.il> wrote:
>> 
>>> 
>>> On 29 Sep 2015, at 19:05, Ian Lepore <ian at FreeBSD.org> wrote:
>>> 
>>> On Tue, 2015-09-29 at 12:24 +0300, Daniel Braniss wrote:
>>>>> On 27 Sep 2015, at 19:35, Ian Lepore <ian at FreeBSD.org> wrote:
>>>>> 
>>>>> On Sun, 2015-09-27 at 19:25 +0300, Daniel Braniss wrote:
>>>>>>> On Sep 27, 2015, at 7:14 PM, Ian Lepore <ian at FreeBSD.org> wrote:
>>>>>>> 
>>>>>>> On Sun, 2015-09-27 at 14:15 +0300, Daniel Braniss wrote:
>>>>> [...]
>>>>>>>> I compiled the u-boot-rpi from ports,
>>>>>>>> the good news:
>>>>>>>> 	it understands UserPreboot
>>>>>>>> the bad news:
>>>>>>>> 	the nfs boot gets stuck after a while.
>>>>>>>> 
>>>>>>>> after much trial and error, this is what I do:
>>>>>>>> 	hit a key to enter U-Boot
>>>>>>>> then type:
>>>>>>>> 	setenv loaderdev net
>>>>>>>> 	boot
>>>>>>>> 
>>>>>>>> attaching the console:
>>>>>>> 
>>>>>>> I was also experiencing intermittant lockups while loader loads the
>>>>>>> kernel.  I just wrote it off to failing hardware (I powered my rpi on
>>>>>>> for the first time in 6-8 months to work on this), since I've never had
>>>>>>> a problem with netbooting before (it's the only way I've ever booted the
>>>>>>> rpi).  If it's not just my board going bad, then that's a bit of a
>>>>>>> mystery.  The only other difference here from what I've always done is
>>>>>>> setting rootpath and other net config in u-boot instead of letting ubldr
>>>>>>> get it from dhcp.
>>>>>> 
>>>>>> with the stuff from crochet it works, same setup! I am sniffing the net via
>>>>>> wireshark, and it stops at different positions in the kernel file,
>>>>>> so the settings of rootpath and other configs are irrelevant.
>>>>>> the transfer is being done via udp/nfs/v3 (hence added ric :-) maybe
>>>>>> he can see something we don´t.
>>>>> 
>>>>> Hmmm.  What stuff from crochet?  The two components that are in play
>>>>> here are u-boot itself (it contains the low-level network drivers that
>>>>> ubldr uses -- it's effectively acting as a bios for ubldr), and ubldr
>>>>> which contains the higher-level network code.
>>>>> 
>>>>> In theory ubldr should be the same in both cases; nothing much has
>>>>> changed in the loader code for months.  But there are different paths
>>>>> through the code depending on how it gets the network parms, and I could
>>>>> easily have glitched something when I added the feature that lets you
>>>>> set the config with u-boot env vars.
>>>>> 
>>>>> The u-boot might be different between a crochet and ports build.  They
>>>>> both start with gonzo's u-boot 2013.10 sources, but crochet probably has
>>>>> a slightly different set of patches it applies.
>>>>> 
>>>>> -- Ian
>>>>> 
>>>> 
>>>> with the old uboot it boots ok, with the newer/modified it stops at random
>>>> places reading via udp/nfs/v3 the kernel. it loads correctly all the *.4th files,
>>>> then starts reading the kernel, and hangs after a random time.
>>>> 
>>> 
>>> I have found that if I let u-boot get an ip address via dhcp then the
>>> load of the kernel in ubldr never fails (I've had it reboot-looping for
>>> 24 hours now without a hang).  But without letting u-boot do the dhcp
>>> thing it hangs pretty much every time.  Substituting a ping <serverip>
>>> for the dhcp isn't enough to make it reliable.
>>> 
>>> I've stopped debugging that whole mess for now to have a quick check
>>> whether the very latest mainline u-boot (2015.10-rc4) is able to
>>> netboot.  It sure would be nice to use something modern that has already
>>> been debugged by others. :)
>> 
>> there is definitely an issue with the net driver in the newer/ports u-boot.
>> 	- tftpboot sometimes works :-)
>> 	- same with nfs
>> 	
>> via dhcp:
>> 	it should not try tftp load filename if none is supplied, i.e. defaulting to
>> 	<mac-address>.img is wrong!
>> 
>> 	i got ubldr loaded via tftp and then bootelf got it running.
>> 	the loaded kernel complained:
>> 		No valid device tree blob found!
>> 	I guess some of the environmet variables got lost
>> 
>> my network is quiet busy, may be thats a factor?
>> 	
>>> 
>>>> on another issue, if I type dhcp instead of boot, it loads via TFTP filename,
>>>> which I set to ubldr/ubldr.bin, it loads and now prompts again,
>>>> what should the command be? I tried go 0, go 20000, in which case execs
>>>> the old ubldr :-(
>>>> 
>>> 
>>> The old ubldr had to be launched using 'bootelf', the new ubldr.bin has
>>> to be launched using "go ${loadaddr}".  While we transition from old to
>>> new I've been using "dhcp <dhcp parms> && bootelf || go ${loadaddr}" --
>>> if it's ubldr the bootelf command works; if bootelf fails it fails back
>>> to using go.
>>> 
>>> -- Ian
>> 
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