Tuesday, April 23rd 2024
JEDEC Updates DDR5 Specification for Increased Security Against Rowhammer Attacks, New DDR5-8800 Reference Speed
JEDEC Solid State Technology Association, the global leader in standards development for the microelectronics industry, today announced publication of the JESD79-5C DDR5 SDRAM standard. This important update to the JEDEC DDR5 SDRAM standard includes features designed to improve reliability and security and enhance performance in a wide range of applications from high-performance servers to emerging technologies such as AI and machine learning. JESD79-5C is now available for download from the JEDEC website.
JESD79-5C introduces an innovative solution to improve DRAM data integrity called Per-Row Activation Counting (PRAC). PRAC precisely counts DRAM activations on a wordline granularity. When PRAC-enabled DRAM detects an excessive number of activations, it alerts the system to pause traffic and to designate time for mitigative measures. These interrelated actions underpin PRAC's ability to provide a fundamentally accurate and predictable approach for addressing data integrity challenges through close coordination between the DRAM and the system.Additional features offered in JESD79-5C DDR5 include:
"The JC-42 Committee is pleased to unveil PRAC, a comprehensive solution to help ensure DRAM data integrity, as an integral component of the DDR5 update. Work is underway to incorporate this feature into other DRAM product families within JEDEC," noted Christopher Cox, JC-42 Committee Chair.
JESD79-5C introduces an innovative solution to improve DRAM data integrity called Per-Row Activation Counting (PRAC). PRAC precisely counts DRAM activations on a wordline granularity. When PRAC-enabled DRAM detects an excessive number of activations, it alerts the system to pause traffic and to designate time for mitigative measures. These interrelated actions underpin PRAC's ability to provide a fundamentally accurate and predictable approach for addressing data integrity challenges through close coordination between the DRAM and the system.Additional features offered in JESD79-5C DDR5 include:
- Expansion of timing parameters definition from 6800 Mbps to 8800 Mbps
- Inclusion of DRAM core timings and Tx/Rx AC timings extended up to 8800 Mbps, compared to the previous version which supported only up to 6400 timing parameters and partial pieces up to 7200 DRAM core timings
- Introduction of Self-Refresh Exit Clock Sync for I/O Training Optimization
- Incorporation of DDP (Dual-Die Package) timings
- Deprecation of PASR (Partial Array Self Refresh) to address security concerns
"The JC-42 Committee is pleased to unveil PRAC, a comprehensive solution to help ensure DRAM data integrity, as an integral component of the DDR5 update. Work is underway to incorporate this feature into other DRAM product families within JEDEC," noted Christopher Cox, JC-42 Committee Chair.
14 Comments on JEDEC Updates DDR5 Specification for Increased Security Against Rowhammer Attacks, New DDR5-8800 Reference Speed
www.anandtech.com/show/21363/jedec-extends-ddr5-specification-to-8800-mts-adds-anti-rowhammer-features
Yeah, not great for anything latency sensitive, so I guess client memory will stick with XMP/EXPO to tighten those up. I assume the new reference is mostly for server/datacenter platforms to increase bandwidth in those workloads when latency isn’t a concern?
Why are the timings sometimes increases by 4 and sometimes only by 2, while each step is 400MT/s?
Are they arbitrarily lowering the timings just to stay within a certian latency limit?
Also: that table has it wrong. (Which is not uncommon for Anandtech.) It should list CL timings for the A, B and C grades but instead, it lists CL timings for the A, A and A grades. The correct values would be around 14 ns, 16 ns and 18 ns, I suppose.
That said, I don't know what the actual reason for that is.
www.techpowerup.com/306762/amd-and-jedec-create-ddr5-mrdimms-with-17-600-mt-s-speeds
But I've seen no news about those recently. Are MRDIMM and MCRDIMM dead? Temporarily dead?
One does wonder what impact this'll have though, if any:
I don't know why jedec repeats the versions up to "4600" with DDR5. Doesn't make sense.
en.wikipedia.org/wiki/DDR4_SDRAM
I'm actually surprised to see them pushing DDR5 specs this much so quickly compared to the past generations, this will at least make up a little bit for the shortcomings of mainstream platforms having only two channels. I do wonder how long it will take Intel and AMD to have CPUs certified for these speeds, it's quite a jump up from their current support of 5600/5200 MHz respectively.
Also, while DDR5 modules below 4800 MT/s probably don't even exist, server processors support maximum speeds as low as 3600 in certain configurations, see thisfor an example. Maybe that's the reason JEDEC had to define lower speeds.
JEDEC DDR4 specs went 2x over base during its lifetime and they're already 2.75x over base with DDR5 which I'm guessing is about enterprise compute density.