Raspberry Pi has announced the release of the first stable 64-bit version of Raspberry Pi OS after almost two years of development and beta testing.
The Debian-based operating system was first unveiled in 2020 alongside the 8GB Raspberry Pi 4 and even though 64-bit processor architectures go back to 2016's Raspberry Pi 3, the previous Raspbian OS was favoured due to backwards compatibility for older devices on 32-bit architectures.
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The decision to move to a 64-bit operating systems was largely driven by forward-looking compatibility concerns, said Gordon Hollingworth, director of software engineering at Raspberry Pi.
"Compatibility is a key concern: many closed-source applications are only available for arm64, and open-source ones aren’t fully optimised for the armhf port," he said.
Armhf port is a Debian port for arm processors that has support for the floating point unit - a feature useful for critical accuracy requirements in computing and digital signal processing.
Hollingworth went on to say there are some performance benefits to the arm64 instructions set but these, at the moment, are only visible in benchmarking tests. That said, the assumption is that these performance increases will be more evident in real-world applications in the future.
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A theoretical concern is that 32-bit architectures only allow the Raspberry Pi to address 4GB of memory. The Raspberry Pi 4 shipped with 8GB back in 2020 and so a 32-bit design would not be optimal to leverage the extra hardware's capabilities.
The Raspberry Pi 4 has been able to access the full 8GB of its memory despite running on a 32-bit operating system since launch, using the Arm Large Physical Address Extension (LPAE), but processes are limited to a maximum of 3GB of memory. Raspberry Pi reserves the top 1GB of the virtual address for the kernel.
Hollingworth noted that very few applications for the Raspberry Pi require the full 8GB of memory in a single process, with Chromium being the most memory-intensive using one process per tab.
"But some use cases will benefit from being able to allocate the entire memory of an 8GB Raspberry Pi 4 from a single process," he added.
Those looking to use their Rasberry Pi as media units will run into a stumbling block when trying to access streaming services such as Netflix and Disney+ as the 64-bit version of Chromium, installed by default, has no version of the WidevineCDM library. Users will have to flicker between the 32-bit versions for streaming and back to 64-bit again after watching through terminal commands.
