Some memory (DDR2 ECC Dual Rank) just doesn't work! Can anyone point me to how to debug this hang?

[Vince Asbridge]

All,

We have an 8548 design, which implements a DDR2 on a SODIMM

We have an issue with dual rank memory (specific part number Viking
VR5DR287218EBSS1), which is a 1G ECC Registered SODIMM part, with two ranks.

Our platform wires CS0 and CS1 to the SODIMM slot.

At uBoot, all is well.  Memory is discovered as ECC 533, 1G DDR2 64Bit 4
beat bursts, and mtest can read and write all 1G of the SODIMM.

Here's where things get bad.

If I boot linux (2.6.11 or 2.6.23 kernel), after the kernel image
decompresses, the machine simply HANGS.

 The IP address of the board is currently set to 192.168.200.90
The MAC address is 00:11:0d:1d:a2:23
If they don't match your network environment, please change them in U-Boot
and kernel manually.
Hit any key to stop autoboot:  0
## Booting image at fc580000 ...
   Image Name:   Linux-2.6.11
   Image Type:   PowerPC Linux Kernel Image (gzip compressed)
   Data Size:    1706305 Bytes =  1.6 MB
   Load Address: 00000000
   Entry Point:  00000000
   Verifying Checksum ... OK
   Uncompressing Kernel Image .   (HANG)

Other DDR2s (identical except for vendor and # of ranks), work perfectly!

Anyone got a clue what I could look at to try to figure this out?

We've tried enable / disable ECC at uboot
We've tried enable / disable Interleaving at uboot

uboot always works (and can read/write entire DDR), Linux always hangs on
boot!

Please help,
Vince









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