[U-Boot] [RFC] Preventing overriding of serverip when set in environment by user

[Wolfgang Denk]

Dear "Maupin, Chase",

In message <7D46E86EC0A8354091174257B2FED10138DD6205 at DLEE12.ent.ti.com> you wrote:
> 
> I recently was trying out a Linksys WRT54G2 V1 router and

Thi sis out-of-tree code, so we cannot help much - we hav eno idea
which modifications they made to the code.

> So the net effect was that the dhcp server in this router was
> providing information in its response packet that was overriding the
> setting I had programmed. I dug into the u-boot code a little and

This is normal, and intended.  If you run DHCP, the information
returned from the server is put in the respective environment
variables.  That's how it works.

Note however, that of course this will not change the persistent copy
of the environment - to do that, you would have to run "saveenv".

> The first was to set CONFIG_BOOTP_SERVERIP in my board config file.
> I discarded this because this would seem to make me always ignore the
> serverip setting from the DHCP server, and it seemed likely that
> there were cases where you would want this.

I don;t understand your description here, but indeed, putting
CONFIG_BOOTP_SERVERIP in the config file almost never makes sense, and
it is definitly not acceptable for mainline.

> The second was to check if the serverip was already set in the
> environment and if so then not override that value with the one in
> the response from the DHCP server. The below patch snippet does this

This is not what is supposed to happen.  You are breaking regular
functionality this way.

> Is this the proper way to fix this issue and the right location to
> make the change? The overall goal was to make sure that if I
> specified a particular serverip that I wanted to use, then the DHCP
> server should not be changing that.

No, this is not an acceptable patch.

What exactly _are_ you trying to fix?  What is wrong with using the
DHCP server supplied address?  If it is incorrect, you should fix your
DHCP server configuration.

Best regards,

Wolfgang Denk

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