NFS Root with Raspberry Pi (nfs_diskless: no interface)

[Ian Lepore]

On Thu, 2015-09-24 at 19:54 +0200, Hans Petter Selasky wrote:
> On 09/24/15 18:36, Randy Westlund wrote:
> > On Thu, Sep 24, 2015 at 08:37:06AM -0600, Ian Lepore wrote:
> 
> >>>[orig problem description: basically nfsroot without BOOTP fails]
> 
> >> Try setting boot.netif.name="ue0" in loader.conf.  I've never tried
> >> that, but in looking at the code, there's some chance it could work.  :)
> >>
> >> What I do is put these options into my RPi kernel config:
> >>
> >> options 	BOOTP
> >> options 	BOOTP_NFSROOT
> >> options 	BOOTP_NFSV3
> >> options 	BOOTP_WIRED_TO=ue0
> >>
> >> But this requires configuring a bootp or dhcp server to provide the
> >> info.  It should be possible to netboot without using BOOTP.
> >>
> >> -- Ian
> >
> > No luck with boot.netif.name.
> >
> > I'm using the kernel that comes in the FreeBSD RPI-B disk image.  Is
> > there a way to see what it was built with?  I tried running strings on
> > the kernel, but I'm not sure what to look for.  Otherwise I guess I'll
> > build one myself.
> >
> > Randy
> >
> 
> Hi,
> 
> The problem is that the code in:
> 
> sys/nfs/bootp_subr.c: SYSINIT(bootp_rootconf, SI_SUB_ROOT_CONF, 
> SI_ORDER_FIRST, bootpc_init, NULL);
> 
> doesn't wait for the USB ethernet device to be enumerated. Only the 
> vfs_mountroot() code which is running from the init-process does so.
> 
> Not sure what the best way to solve this is. Try putting:
> 
> pause("W", hz * 4);
> 
> Into the beginning of the "bootpc_init()" function.
> 
> --HPS

I had time to look into this today.  The bootpc_init() routine *does*
wait for an interface to appear.  The problem in this case is that BOOTP
isn't involved, and the nfs_setup_diskless() routine doesn't have a
similar wait loop for slow interfaces.  The attached patch adds it, and
with it I can nfsmount root on my RPi without using the BOOTP_foo
options I listed above.

Rick, does this patch look okay to you?  If no objections, I'll commit
this asap.

-- Ian

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