On Sun, 11 Sep 2011 10:09:45 +0200, Jean Delvare <khali@xxxxxxxxxxxx>
wrote:
Hi Michal,
...
Second preliminary note: as far as I know, memtest86 reads SPD
information using a BIOS call, while decode-dimms gets the information
over the SMBus, assuming that SPD EEPROMs are connected to the SMBus
and reachable at run time. This difference in access methods can
explain why memtest86 can see information and decode-dimms not on the
same system.
Is there a way to do the BIOS call method in Linux? If it's a sort-of
standard way to access SPD info, would it be the one used by CPU-Z to read
the SPD info on Windows? (which does work on this HW)
First thing to check is if the SMBus on your system is properly found
and supported:
# modprobe i2c-dev
# i2cdetect -l
On an Intel system you should see an entry like:
i2c-8 smbus SMBus I801 adapter at 0400 SMBus adapter
Nope. On 'buntu 10.10, I only got 5 entries (didn't write them down), none
of which said smbus. On 11.10, I get:
# i2cdetect -l
i2c-0 i2c i915 gmbus disabled I2C adapter
i2c-1 i2c i915 gmbus ssc I2C adapter
i2c-2 i2c i915 GPIOB I2C adapter
i2c-3 i2c i915 gmbus vga I2C adapter
i2c-4 i2c i915 GPIOA I2C adapter
i2c-5 i2c i915 gmbus panel I2C adapter
i2c-6 i2c i915 GPIOC I2C adapter
i2c-7 i2c i915 gmbus dpc I2C adapter
i2c-8 i2c i915 GPIOD I2C adapter
i2c-9 i2c i915 gmbus dpb I2C adapter
i2c-10 i2c i915 GPIOE I2C adapter
i2c-11 i2c i915 gmbus reserved I2C adapter
i2c-12 i2c i915 gmbus dpd I2C adapter
i2c-13 i2c i915 GPIOF I2C adapter
i2c-14 i2c SDVO DDC proxy I2C adapter
And BTW, this is the same list I get on my "server/router/AP" (Intel
D945GSEJT nettop board running 'buntu 11.04) which is also in the same
situation (can't read SPD info).
Then you can check if devices are seen on the bus:
# i2cdetect 8
If you see anything in address range 0x50 to 0x55, this is likely to be
SPD EEPROMs. Then you have to make sure that the eeprom module is
loaded:
From the above list, buses 3-6 have a value 0x50 at 0x50 like so:
# i2cdetect -y 5
0 1 2 3 4 5 6 7 8 9 a b c d e f
<snip>
50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
Though that's probably irrelevant, as it's not the SMBus, if I understand
correctly.
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