Re: [Qemu-devel] Re: NE2000 problem found

[Leigh Dyer <leigh@eclinic.com.au>]

On Thu, 2004-06-10 at 07:21 +0200, Mike Nordell wrote:
> I wrote:
> 
> > It's also the thing that it seems only about every second time
> > networking "works", to the extent the guest actually gets a
> > DHCP address.
> 
> I have now identified, and "fixed" this problem it seems. I have rebooted
> four times, and the guest has gotten an IP every time.
> 

I hadn't seen any more news on this, and I didn't see any patches
committed to CVS to fix this, so I thought I'd mention that I too see
this problem with Windows 2000 (it only gets an IP address from the DHCP
server on every second boot), and that this fix seems to solve the
problem for me as well.

Thanks
Leigh

> It was that Windows cached the previous IP and tried to get that again on
> next reboot, using DHCPREQUEST. Unfortunately, that failed miserably with
> the CVS QEMU/slirp DHCP server. Basically, the code just dropped the request
> and therefore the guest never got an IP.
> 
> When Windows didn't get an IP, it noted so, and on the next reboot used
> DHCPDISCOVER - which works - and so the merro-go-around starts over again on
> next reboot. :-)
> 
> I "fixed" it in a really Q&D way (probably wrong, and please don't hold the
> "goto" against me - I just wanted to display with as little code as possible
> how it could be fixed)
> 
> bootp_reply, in bootp.c
> 
> +try_again:
>     if (dhcp_msg_type == DHCPDISCOVER) {
> ...
>     } else {
>         bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
>         if (!bc) {
>             dprintf("no address assigned\n");
> +#if 1
> +            dhcp_msg_type = DHCPDISCOVER;
> +            goto try_again;
> +#else
>             return;
> +#endif
>         }
> 
> 
> /Mike
> 
> 
> 
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