[PATCH 5/7] discover/platform-powerpc: Add NVRAM parameter for IPv6

Samuel Mendoza-Jonas sam at mendozajonas.com
Mon May 14 13:17:14 AEST 2018


On Mon, 2018-05-14 at 09:56 +0800, Jeremy Kerr wrote:
> Hi Sam,
> 
> > Add a new NVRAM parameter to signal which address scheme should be used.
> > This is kept separate from petitboot,network to maintain some backwards
> > compatibility for IPv4 configurations.
> 
> I'm not 100% convinced we need this to be explicitly set.
> 
> For specifying petitboot's own network settings, could we not detect
> this at interface-configuration time, based on the format of the
> addresses in the petitboot,network parameter? When doing DHCP, we could
> start both v4 and v6 discovery.

On reflection this completely makes sense!
One scenario that comes to mind is if some users might want to restrict
which format is used if both are available, but I'm not sure how common
of a request that would be (eg. both are available but only one routes to
somewhere useful - that could have an effect on async loads potentially).

In general though nothing really stops us from doing both simultaneously
- perhaps just some extra logic to check if the IPv6 addresses we have
are link-local only.

> 
> And for detecting the v4/v6-iness of external URLs, that could just
> depend on the format of the URLS (if they're explicit IPs, either v4 or
> v6) or type of answer records we get back from DNS?

Indeed we already do this in device_from_addr().

Cheers,
Sam

> 
> Cheers,
> 
> 
> Jeremy



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