[coreboot] Supermicro H8QME-2+ mct_d fatal exit.

Knut Kujat knuku at gap.upv.es
Fri Mar 12 12:27:15 CET 2010


Rudolf Marek escribió:
>
>> I finally know that my issue must be related with the smbus registers
>> because on a vendor bios running machine and using i2cdetect and i2cdump
>> I get several values for different i2c devices detected, I get the same
>> values when I successfully start with coreboot. But when I start with
>> coreboot and fail with mcr_d fatal exit those registers are blank, I
>> know that because I found a nice piece of code dumping smbus registers
>> on the h8dme board :D thx to the autor!!
>>
>> I also know that reading these registers out may cause them to get lost!
>> I'm not sure why?!
>>
>>   
>
> There is a multiplexer on SMBus, this confirms my theory. Please check
> the GPIO.
>
> Imagine the multiplexer acts as some kind of rail switch. The
> transactions on smbus never reach thhe memory chips (the SPD eeprom).
> You need to find a pin to control the multiplexer.
>
> Rudolf
Thanks, because of your hints I was able to figure out that I needed to
set up the spd_rom in romstage.c I also added the GPIOs settings as read
from vendor BIOS and now the power on led works :).

thx,
Knut Kujat.

>
>
>
>> Now my question is how do I initialize these registers with the values
>> known from the vendor BIOS? smb_write_byte doesn't seems to work or
>> maybe I'm using it wrong.
>>
>> THX,
>> Knut Kujat.
>>
>>
>>
>> Knut Kujat escribió:
>>  
>>> Hello,
>>>
>>> thx all of you for your comments. Here a little update :)
>>>
>>> I now know why the boards worked just fine up here in my lab. To
>>> know if
>>> the board would work after being unplugged I always "only" unplugged
>>> the
>>> electrical cable but never the monitor attached to the board I figured
>>> out that the monitor is providing enough juice to maintain whatever
>>> alive in the board so after plugging the electrical cable on again
>>> coreboot started fine. Another thing I figured out is that it seems
>>> that
>>> the front leds of the board a managed by GPIO as well, is this
>>> right? If
>>> so it seems that something is wrong with GPIO because the power on led
>>> never works with coreboot.
>>>
>>> thx,
>>> Knut Kujat.
>>>
>>>
>>>
>>> ron minnich escribió:
>>>      
>>>> Just FYI:
>>>>
>>>> on our first system with Arima boards in 2002, everything worked well
>>>> until we started booting 64-bit kernels. I'm not kidding. We did not
>>>> find the SMBUS MUX on the boards until we had unreliable coreboot
>>>> boots of 64-bit kernels. For quite some time the boards worked fine.
>>>> Ollie found the SMBUS MUX by examining schematics.
>>>>
>>>> So the SMBUS mux can appear in strange ways, at strange times. This
>>>> sounds like one of those times. SMBUS muxes are more common than you
>>>> might think and the default power-on state is not always very well
>>>> determined.
>>>>
>>>> ron
>>>>
>>>>             
>>>       
>>
>>   
>
>
>





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