cyring/gist:eb13992a3b9482eb4bde77a2cf62c605

Created March 18, 2024 12:34

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DIMM 24-48 GB

Raw

gistfile1.txt

AMD UMC

Author

cyring commented Mar 18, 2024

The DIMM size formula is:

8 * (Bank * Rank * Rows * Columns) Bytes

Using geometry values, applying formula in GB

echo $(( (8*(32*1*131072*2048))/(1024*1024*1024) ))

Refering to Ryzen 7950X datasheet

Based on the dump register

# ./zencli smu 0x50040

[0x00050040] READ(smu) = 0x0026070c (2492172)
   60   56   52   48   44   40   36   32   28   24   20   16   12   08   04   00
 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0110 0000 0111 0000 1100

We are getting in bit field [19:16] a value of 0110 (bin) or 6 (dec)

Thus the number of columns is:

echo $(( 1<<(5+6) ))

A number of 2048 columns is new to me.
Up to now, all Zen' UMC have returned 1024

if we assume that 0110 (bin) rather means 1536, we are getting:

echo $(( (8*(32*1*131072*1536))/(1024*1024*1024) ))

Author

cyring commented Mar 21, 2024 •

edited

24GB DIMM case : UNSOLVED

Rank = 1

[0x00050040] READ(smu) = 0x00150508 (1377544)
   60   56   52   48   44   40   36   32   28   24   20   16   12   08   04   00
 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0001 0101 0000 0101 0000 1000

Field	Bin	Dec	Compute	Result
NumBanks	01	1	`8 << 1`	16
NumCol	0101	5	`1 << (5+5)`	1024
NumRow	0101	5	`1 << (10+5)`	32768

echo $(( (8*(16*1*32768*1024))/(1024*1024*1024) ))

4 GB

[0x00050048] READ(smu) = 0x0025070c (2426636)
   60   56   52   48   44   40   36   32   28   24   20   16   12   08   04   00
 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0101 0000 0111 0000 1100

Field	Bin	Dec	Compute	Result
NumBanks	10	2	`8 << 2`	32
NumCol	0101	5	`1 << (5+5)`	1024
NumRow	0111	7	`1 << (10+7)`	131072

echo $(( (8*(32*1*131072*1024))/(1024*1024*1024) ))

32 GB

[0x0005004c] READ(smu) = 0x00150508 (1377544)
   60   56   52   48   44   40   36   32   28   24   20   16   12   08   04   00
 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0001 0101 0000 0101 0000 1000

Field	Bin	Dec	Compute	Result
NumBanks	01	1	`8 << 1`	16
NumCol	0101	5	`1 << (5+5)`	1024
NumRow	0101	5	`1 << (10+5)`	32768

4 GB

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