ARM unveils 64-bit architecture

by Sylvie Barak , TechOnline India - October 28, 2011

The first processors based on ARMv8 will only be announced sometime in 2012, with actual server prototypes running on the new architecture expected in 2014.

ARM Holdings has announced that its next-gen ARMv8 architecture will include the firm’s first 64-bit instruction set, pushing ARM-based processors into new segments of the consumer and enterprise markets.

Speaking at ARM TechCon 2011 in Santa Clara, Calif., ARM Chief Technology Officer Mike Muller said the new v8 architecture would consist of two main execution states: AArch64 and AArch32, with the former introducing a new A64 for 64-bit processing instruction set, while the latter would continue to support ARM’s existing instruction set.

“ARM V8 fully supports 32 bit ARMv7a software,” said Muller, adding that the architecture had been designed to “maximize the benefits across both 32-bit and 64-bit application areas."

This, he said, “would bring the advantages of energy-efficient 64-bit computing to new applications such as high-end servers and computing, as well as offering backwards compatibility and migration for existing software through a consistent architecture."

“A 64 bit OS can easily and efficiently support existing 32 bit software,” he explained.

Taking a dig at rival Intel Corp., Muller said that though the world had been done very well by Moore’s Law, “there’s nowhere else to go.” Muller said while more cores was certainly a good trend, ARM believed the future would be found in having “lots of power efficient cores rather than some more power inefficient cores.” Muller maintained that overall, the problems came down to the system level, not the cores. 

ARM partners like Nvidia Corp. have already announced plans to target the server space, but before the announcement of 64-bit ARM architecture, that vision didn’t translate into much of a competitive reality, as server buyers were not likely to invest in machines that couldn’t handle the software they were running.

Despite the significance of the announcement, however, Muller warned that building a new architecture was not “a quick thing” and would take a few years, but was important in terms of scaling for ARM’s future. “It takes time to build ecosystems and we’re fully aware of that,” he said.

Indeed, the first processors based on ARMv8 will only be announced sometime in 2012, with actual server prototypes running on the new architecture expected in 2014.

“ARM was going to need to go 64-bit in the next 4-5 years for cell phones and tablets anyway,” explained analyst David Kanter of Real World Technologies. “The interesting part is that ARM partners such as Calxeda and Nvidia are clearly planning to target the server space, heading for a direction collision course with AMD, IBM, Intel and Oracle,” he said.

The question, said Kanter, was not whether ARM's 64-bit extensions would be perfectly functional, but whether ARM partners could deliver competitive products with the performance, power efficiency and reliability that customers require.

“Obviously Nvidia's strategy is going to be targeting HPC with GPUs, but that has never proven to be a market which can economically sustain a chip design company, much to SGI's detriment,” Kanter noted.

Another disadvantage, Kanter pointed out, was that most of ARM's partners were fabless and had less expertise when it came to custom design, unlike incumbents AMD, IBM, Intel and Oracle.  

“They also have much less experience with the overall system and platform aspects, including the validation and testing required,” he said, explaining that for a product like a GPU –with a lifespan of about a year-- there wasn’t typically as much emphasis on correctness because bugs could be worked around. “In a server, there is very little tolerance for such things,” he said.

In his keynote address, Muller also spoke about the increased need for more heterogeneous computing, system partitioning, and solving the problems of energy efficiency in devices as systems became increasingly complex and memory intensive.

“Today, everything is an energy constrained system,” he said adding, “the solutions are all about building heterogeneous solutions.”

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