[correct_horse]

This is good news. I had assumed that raspbian was 64 bit by now. It seems weird, since the Raspberry Pi v2.1 (second revision of Raspberry pi 2) launched with a 64-bit processor. I can't find a date for that launch, but the pi 3 launched in February 2016. The Pi foundation was forthcoming about Raspbian being 32 bit in the pi3 announcement article, but the timescale they laid out for making it 64 bit was "the next few months". I guess the reason anyone bothered porting to 64 bit is the fact that the pi4 has a 4GB of RAM option (you can't address the full 4GB with 32 bits).

[praseodym]

Debian arm64 works fine on the Raspberry Pi 3 (https://wiki.debian.org/RaspberryPi). The Pi 4 changed the boot sequence so that Debian doesn’t work any more, making this the first 64-bit OS for the Pi 4.

[weare138]

They didn't say it is the first 64bit OS that runs on the Pi 4. The key phrase is "fully functional" which has no definitive definition. It's just some clickbait, marketing jargon.

[Wowfunhappy]

> you can't address the full 4GB with 32 bits

Sure you can, you use page tables.

[voxadam]

Exactly, didn't Arm add support for Large Physical Address Extension (LPAE) back in the v7 days?