Developer Manual/RAM init: Difference between revisions
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One of the most important tasks of coreboot is to initialize your system RAM. | === Introduction === | ||
One of the most important tasks of coreboot is to '''initialize your system RAM'''. | |||
This initialization depends on the type of RAM in your motherboard. To detect the type of RAM the | |||
SPD (Serial Presence Detect) must be read for each DIMM. This reading is done using I2C communication using one of the [[Developer Manual/I2C]] buses on the motherboard. The exact method of reading depends on the motherboard. | |||
=== SDRAM === | === SDRAM === | ||
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* http://support.intel.com/design/chipsets/datashts/290656.htm | * http://support.intel.com/design/chipsets/datashts/290656.htm | ||
* http://download.intel.com/design/chipsets/datashts/29065602.pdf | * http://download.intel.com/design/chipsets/datashts/29065602.pdf | ||
* http://www.intel.com/Assets/PDF/datasheet/307502.pdf | |||
* http://www.intel.com/assets/pdf/datasheet/318463.pdf | |||
Sample SDRAM datasheets: | Sample SDRAM datasheets: | ||
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SDRAM: | SDRAM: | ||
<!--* [ JEDEC SDRAM Standard] TODO --> | <!--* [ JEDEC SDRAM Standard] TODO --> | ||
* [http://www.intel.com/design/chipsets/memory/spdsd12a.pdf Intel SPD Standard] | * [http://web.archive.org/web/20050307195215/http://www.intel.com/design/chipsets/memory/spdsd12a.pdf Intel SPD Standard] | ||
<!--* [ JEDEC SPD Standard] TODO --> | <!--* [ JEDEC SPD Standard] TODO --> | ||
* [http://download.micron.com/pdf/datasheets/dram/sdram/512MbSDRAM.pdf Micron 512 MB SDRAM Datasheet] (PDF) -- contains some helpful explanations | * [http://download.micron.com/pdf/datasheets/dram/sdram/512MbSDRAM.pdf Micron 512 MB SDRAM Datasheet] (PDF) -- contains some helpful explanations | ||
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DDR2 SDRAM | DDR2 SDRAM | ||
* [http://www.jedec.org/download/search/JESD79-2C.pdf JEDEC DDR2 Standard] (PDF) | * [http://www.jedec.org/download/search/JESD79-2C.pdf JEDEC DDR2 Standard] (PDF) | ||
* [http://www.simmtester.com/PAGE/news/showpubnews.asp?where=373939&num=139 DDR2 DIMM SPD Definition] | * [http://www.simmtester.com/PAGE/news/showpubnews.asp?where=373939&num=139 DDR2 DIMM SPD Definition] | ||
* Micron DDR2 Datasheets: [http://download.micron.com/pdf/datasheets/modules/ddr2/HTF16C64_128_256x64AG.pdf 512MB-2GB] [http://download.micron.com/pdf/datasheets/modules/ddr2/HTF16C64_128_256x64A.pdf 512MB-4GB] | |||
DDR3 SDRAM | DDR3 SDRAM | ||
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* [http://www.simmtester.com/PAGE/news/showpubnews.asp?num=153 Understanding DDR3 Serial Presence Detect (SPD) Table] | * [http://www.simmtester.com/PAGE/news/showpubnews.asp?num=153 Understanding DDR3 Serial Presence Detect (SPD) Table] | ||
Note: Micron lists SPD values for all the memory they produce. This really helps when trying to trouble shoot memory and SPD values. | '''Note:''' Micron lists SPD values for all the memory they produce. This really helps when trying to trouble shoot memory and SPD values. [http://www.micron.com/support/part_info/spd Micron SPD Lookup]. |
Revision as of 19:32, 1 April 2011
Introduction
One of the most important tasks of coreboot is to initialize your system RAM.
This initialization depends on the type of RAM in your motherboard. To detect the type of RAM the SPD (Serial Presence Detect) must be read for each DIMM. This reading is done using I2C communication using one of the Developer Manual/I2C buses on the motherboard. The exact method of reading depends on the motherboard.
SDRAM
There are a number of steps you have to perform to properly initialize SDRAM. This depends on the chipset, as well as the DIMMs which are inserted into the mainboard (and their properties, such as CAS latencies, and so on).
Sample northbridge datasheets:
- http://support.intel.com/design/chipsets/810/
- http://support.intel.com/design/chipsets/datashts/290656.htm
- http://download.intel.com/design/chipsets/datashts/29065602.pdf
- http://www.intel.com/Assets/PDF/datasheet/307502.pdf
- http://www.intel.com/assets/pdf/datasheet/318463.pdf
Sample SDRAM datasheets:
- http://www.micron.com/products/partdetail?part=MT48LC16M16A2BG-75
- http://download.micron.com/pdf/datasheets/dram/sdram/256MSDRAM.pdf
DDR
DDR2
DDR3
Resources
SDRAM:
- Intel SPD Standard
- Micron 512 MB SDRAM Datasheet (PDF) -- contains some helpful explanations
DDR SDRAM:
- JEDEC DDR SPD Standard (PDF)
- Understanding DDR Serial Presence Detect (SPD) Table
- Micron DDR400 Datasheet
DDR2 SDRAM
- JEDEC DDR2 Standard (PDF)
- DDR2 DIMM SPD Definition
- Micron DDR2 Datasheets: 512MB-2GB 512MB-4GB
DDR3 SDRAM
Note: Micron lists SPD values for all the memory they produce. This really helps when trying to trouble shoot memory and SPD values. Micron SPD Lookup.