Re: PROBLEMS WITH DNS

[Paulo Marques <pmarques@grupopie.com>]

Vadim Lebedev wrote:
> Paulo Marques wrote:
> 
>> Vadim Lebedev wrote:
>>
>>> Eduardo Franceschini wrote:
>>> [...]
>>>
>>>> I can get an IP, but when I go to /etc/resolv.conf , I don't have an 
>>>> IP for
>>>> DNS server... somebody know what to do?
>>>
>>> [...]
>>> Maybe one why to do it is to modify kernale mode dhcp client to 
>>> create a procfs entry containig info for resolv.conf
>>> and have /etc/resolv.com  to be symlink to procfs entry
>>
>>
>> I'd say this is just the opposite direction of where things seem to be 
>> going nowadays.
>>
>> AFAICS, the current solution to this problem is to use initrd / 
>> initramfs with a user-space dhcp client and nice script to get the DNS 
>> information into /etc/resolv.conf.
>>
>> With this in place you can even drop the DHCP / NFS-root support from 
>> the kernel and have it all done in user-space.
>>
>> This seems to be the current trend, and I wouldn't be surprised if the 
>> options for IP auto config and NFS root were dropped from mainline in 
>> the future.
>>
> Kernel mode dhcp client solutions allows muuch faster boot sequences...
> for embedded stuff 15-20 secs boot speed advantage is important....

I can't see why a user space client running from initramfs with 
basically the same code as the in-kernel dhcp client would be much 
slower. I'd be surprised if the difference is more than a few milliseconds.

So the real problem is to find a dhcp client that is actually as simple 
as the in-kernel one. "udhcpc"[1] might just do what you want.

The only other argument I can see for in-kernel dhcp is that it is 
easier to configure than it is to setup an initramfs filesystem. As soon 
as that problem is somehow solved, I don't see the advantage in keeping 
the in-kernel version.

-- 
Paulo Marques - www.grupopie.com

"Very funny Scotty. Now beam up my clothes."

[1] http://udhcp.busybox.net/

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