about netbooting on armv6 [was: Fwd: SDIO Patch D4761.diff Not Building For Me]

[Daniel Braniss]

> On 23 Mar 2016, at 18:43, Ian Lepore <ian at FreeBSD.org> wrote:
> 
> On Wed, 2016-03-23 at 09:09 -0700, Russell Haley wrote:
>> On Wed, Mar 23, 2016 at 4:00 AM, Ilya Bakulin <ilya at bakulin.de>
>> wrote:
>>> On 2016-03-23 06:16, Russell Haley wrote:
>>>> 
>>>> Hi Ilya,
>>>> 
>>>> Mixed success tonight. I tried to install the kernel but got an
>>>> error:
>>> 
>>> 
>>> You should give MODULES_OVERRIDE= to installkernel as well.
>>> 
>> Great, Thank you.
>>>> 
>>>> Well, it booted the kernel and then spewed output and eventually
>>>> ended
>>>> with a failed DHCP request (?). Here is the pastebin of said
>>>> output.
>>>> 
>>> 
>>> I never copy the newly built kernel to the SD card.
>>> Instead I configure U-Boot+ubldr to boot kernel from TFTP and mount
>>> root
>>> over NFS, it's much faster and it's impossible to crash filesystem
>>> if the
>>> kernel crashes.
>>> I guess you should set ROOTDEVNAME manually in the kernel config
>>> file and
>>> disable NFSCLIENT-related options.
>> 
>> Thanks for this advice. I have had something similar working before
>> (I
>> had rootfs on USB) so should be able to get that running this weekend
>> 
>>> From your boot log it's clear that the system boots and probes SD
>>> cards.
>> 
>> Yes, very exciting to see!!! I will be looking to try and match debug
>> output with code paths asap.
>> 
>>> There are two slots and none of them has SDIO card in it.
>>> From what I find about Hummingboard, it actually doesn't have WiFi
>>> SDIO
>>> chips on it.
>> 
>> I don't understand. It was booted using an SD card? Also, here is the
>> information about the board and the Wi-Fi (the Solid-Run site can be
>> hard to navigate):
>> 
>> Carrier Board spec:
>> http://wiki.solid-run.com/doku.php?id=products:imx6:hummingboard:hbpr
>> o
>> 
>> This is my SOM:
>> http://wiki.solid-run.com/doku.php?id=products:imx6:microsom:dual&s[]
>> =bcm4330
>> 
>> Schematic. I believe page 5 shows the SDIO WIFI module interface?
>> http://wiki.solid-run.com/lib/exe/fetch.php?media=imx6:microsom:docs:
>> sr-usom-mx6-rev-1_3-simplified-schematics.pdf
>> 
>> Broadcom BCM4330
>> http://linux-sunxi.org/images/0/05/4330-DS206-R.pdf
>> 
>> I have used it successfully through Kodi and Debian (Raspbian
>> specifically)
>> 
>> Thanks,
>> Russ
> 
> The quick and easy config for netbooting armv6 these days is to set a
> few vars in your uboot env.  This assumes that you let uboot load
> ubldr.bin from sdcard, and then have ubldr load the kernel and the
> kernel will mount nfsroot.
> 
> If you have a dhcp server to provide an IP, this is all you need in
> uboot env:
> 
>  loaderdev=net
>  rootpath=<nfs server ip>:/<rootpath>

you can set the footpath via dhcp / dhcpd.conf:

option root-path “nfs:ip.root.host:/path-to-root”;

> 
> If you manually configure the ip, add these:
> 
>  ipaddr=<ip addr>
>  netmask=255.etc.etc.etc
> 
> When ubldr loads the kernel via nfs, it also sets up all the info
> needed to mount root via nfs and passes the info to the kernel in env
> vars.  It will also set vfs.root.mountfrom to the server:path you set
> in the rootpath var in uboot, which gets the initial root fs mount
> done.  You still need an /etc/fstab that also has the nfs mount info
> for the nfsroot, so that the rc scripts can remount root writable.
> 
> All you need in the kernel config is options NFSCL, NFSLOCKD, NFS_ROOT
> and all of those are already standard in all armv6 kernels.  You don't
> need to change the ROOTDEVNAME option because the vfs.root.mountfrom
> overrides it (ROOTDEVNAME is used as a fallback if the nfs mount
> fails).
> 
> -- Ian
> 
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