imb-a180 won't boot from single DIMM 0

[Mark C. Mason]

Is there a straightforward way to get an IMB-A180 to boot with a single
DIMM in slot 0?  It boots fine in slot 1.  I've looked through the code
at length, and thought it configures the dimm, it fails in

coreboot/src/vendorcode/amd/agesa/Proc/Mem/Main/KB/mmflowKB.c

//----------------------------------------------------
   // If there is no dimm on the system, do fatal exit
   //----------------------------------------------------
   if (NBPtr[BSP_DIE].RefPtr->SysLimit == 0) {
     PutEventLog (AGESA_FATAL, MEM_ERROR_NO_DIMM_FOUND_ON_SYSTEM, 0, 0, 
0, 0, &(MemMainPtr->MemPtr->StdHeader));
     return AGESA_FATAL;
   }

Even though it has detected and configured the dimm in slot 0.
Again, this does work with slot 1.

Many thanks,

Mark Mason
Engineering Design Team

[Scott Duplichan]

Mark C. Mason [mailto:[e-mail]] wrote:

]Is there a straightforward way to get an IMB-A180 to boot with a single
]DIMM in slot 0?  It boots fine in slot 1.  I've looked through the code
]at length, and thought it configures the dimm, it fails in
]
]coreboot/src/vendorcode/amd/agesa/Proc/Mem/Main/KB/mmflowKB.c
]
]   //----------------------------------------------------
]   // If there is no dimm on the system, do fatal exit
]   //----------------------------------------------------
]   if (NBPtr[BSP_DIE].RefPtr->SysLimit == 0) {
]     PutEventLog (AGESA_FATAL, MEM_ERROR_NO_DIMM_FOUND_ON_SYSTEM, 0, 0, 
]0, 0, &(MemMainPtr->MemPtr->StdHeader));
]     return AGESA_FATAL;
]   }
]
]Even though it has detected and configured the dimm in slot 0.
]Again, this does work with slot 1.
]
]Many thanks,
]
]Mark Mason
]Engineering Design Team

A few years ago the agesa code was changed to make
the DIMM population order rules a requirement rather
than a recommendation. This is a BKDG requirement.
Agesa excludes the out of place DIMM. If it is the
only DIMM in the system, then the error logic will
report no DIMM installed. This might be what you
are seeing. There may be an agesa warning for this
that isn't getting reported. The DIMM population
order rules are related to signal integrity and are
explained in the BKDG.
Thanks,
Scott