Kernel boot hangs by parallel flood pings

Steffen Rumler Steffen.Rumler at
Wed Jan 12 19:38:03 EST 2005

I'm using a 2.4.20 kernel (PPC).

When I run multiple 'ping -f' directed to my board
during the kernel boots, sometimes it hangs with
the following messages:

   Memory BAT mapping: BAT2=64Mb, BAT3=32Mb, residual: 84Mb
   Linux version 2.4.20-rthal5 (ru at styx) (gcc version 2.95.3 20010111 (prerelease/franzo/20010111))
   #9 Tue Jan 11 17:09:22 CET 2005
   On node 0 totalpages: 29859
   zone(0): 29859 pages.
   zone(1): 0 pages.
   zone(2): 0 pages.
   Kernel command line: bootdev=aps0 ip=
   panic=1 mem=119436k
   Calibrating delay loop... 194.15 BogoMIPS
   NET4: Linux TCP/IP 1.0 for NET4.0
   IP Protocols: ICMP, UDP, TCP
   IP: routing cache ha
                   the kernel boot hangs here

I have checked this with the BDI2000 and found that the
kernel loops anywhere inside ip_route_input().

I think this is because the ethernet driver (fcc_enet.c)
enables the hardware too already inside it's init routine (fec_enet_init()).

In this way, frames may be received and forwarded to the upper
layers with netif_rx(), before the TCP/IP was initialized.

I suggest to delay the lines

   /* Enable transmit/receive */
   fccp->fcc_gfmr |= FCC_GFMR_ENR | FCC_GFMR_ENT;

to the open entry point (fcc_enet_open()), which is
triggered by 'ifconfig up' in the following way:

   if(!((fccp->fcc_gfmr) & FCC_GFMR_ENR))
      fccp->fcc_gfmr |= (FCC_GFMR_ENR | FCC_GFMR_ENT);

By the way, fcc_enet_close() does _NOT_ stop the hardware.
Hopefully, this is not a real problem.




Steffen Rumler
Siemens AG
Hofmannstr. 51                 Email: Steffen.Rumler at
D-81359 Munich                 Phone: +49 89 722-44061
Germany                        Fax  : +49 89 722-36703


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