Raspberry PI 3 - 32bit -> 64bit upgrade possible?

[Evils]

I've recently bought a RPI3 and set it up with the latest and greatest Arch Linux.

Now as the arch linux page rightfully says, the current builds are all 32bit and therefore the CPU won't be fully used on the PI3.
What I do wonder now, once's the kernel and everything else would potentially fully support the armv8 CPU and it's 64bit architecture, would I simply be able to upgrade using pacman or would that require me to setup my pi from scratch?

Thanks in advance for any answer

[klricks]

From what I understand the 64b version is a possibility for the future but not a priority. If/when that happens I expect it to be a completely separate OS.

Edit: Did not realize this was in the Arch forum......

[loganmc10]

I don't think "CPU won't be fully used" is a good way to describe the impact of going from 32bit to 64bit. The difference will be far less dramatic than you think.

But to answer the question, you'll need to do a fresh install, there will be no way to upgrade from 32 to 64 bit.

[DougieLawson]

But to answer the question, you'll need to do a fresh install, there will be no way to upgrade from 32 to 64 bit.

Nonsense. I'd expect 32-bit programs to run OK with a 64-bit kernel, they've just got to ensure the interfaces they use are 32-bit aware and can work with addresses that are below the great divide. It's all about providing forward and backward compatibility.

What's being done with ARM processors isn't new (it seems to me there's nothing new). Mainframes went from 24-bit to 31-bit in 1983 then went from 31-bit to 64-bit in 2000. You can take a mainframe program from the 1960s and it will run on a modern 64-bit mainframe.

Why shouldn't a 32-bit user space program run with a 64-bit kernel? I don't disagree there may be some benefits by building programs that are 64-bit only, but that's an entirely different thing.

[loganmc10]

But to answer the question, you'll need to do a fresh install, there will be no way to upgrade from 32 to 64 bit.

Why shouldn't a 32-bit user space program run with a 64-bit kernel? I don't disagree there may be some benefits by building programs that are 64-bit only, but that's an entirely different thing.

They were asking if they would be able to use pacman to upgrade from the 32-bit kernel/userspace to the 64-bit kernel/userspace. That won't be possible. Yes 32 bit applications will probably work on the 64-bit kernel, but to install the 64-bit kernel they will need to re-install Arch Linux, they won't be able to upgrade using pacman.

[Koeshi]

But to answer the question, you'll need to do a fresh install, there will be no way to upgrade from 32 to 64 bit.

Why shouldn't a 32-bit user space program run with a 64-bit kernel? I don't disagree there may be some benefits by building programs that are 64-bit only, but that's an entirely different thing.

They were asking if they would be able to use pacman to upgrade from the 32-bit kernel/userspace to the 64-bit kernel/userspace. That won't be possible. Yes 32 bit applications will probably work on the 64-bit kernel, but to install the 64-bit kernel they will need to re-install Arch Linux, they won't be able to upgrade using pacman.

Why wouldn't you be able to do that when with distros like Manjaro, which is based off Arch, you can upgrade the kernel without re-installing?

[loganmc10]

Why wouldn't you be able to do that when with distros like Manjaro, which is based off Arch, you can upgrade the kernel without re-installing?

You can upgrade the kernel version, but you can't change architectures. You can't go from x86 to amd64 (on Intel chipsets) and you can't go from armv6h to armv7h to aarch64 on ARM chipsets, you have to do a fresh install. Every single piece of software on the system is compiled for the particular architecture of the kernel that you have installed.

[ghans]

https://wiki.debian.org/CrossGrading
https://wiki.archlinux.org/index.php/Mi ... hitectures

It's generally considered insane - but hey , we have anecdotal
evidence that it works !

An AArch32 userland should run fine on top of an AArch64
kernel , too .


ghans

[loganmc10]

https://wiki.debian.org/CrossGrading
https://wiki.archlinux.org/index.php/Mi ... hitectures

It's generally considered insane - but hey , we have anecdotal
evidence that it works !

An AArch32 userland should run fine on top of an AArch64
kernel , too .

Ok I suppose you could go through all that work, but realistically who is going to do that when you can just backup your files, take out the SD card and reinstall?