nematode
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Raspbian Stretch not 64bit?

Sat Sep 02, 2017 1:24 pm

I thought raspbian stretch was 64bit. I installed it on my pi3 hoping to use PocketMine-MP (32bit no longer supported). However, it still says 32bit no longer supported and the command getconf LONG_BIT returns 32. Is raspbian ever going to go to 64bit?

DirkS
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Re: Raspbian Stretch not 64bit?

Sat Sep 02, 2017 1:28 pm

No, it's still 32-bit.
And it's unlikely there will ever be an official RPF 64-bit release. Basically too much effort for very little (or no) gain.

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rpdom
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Re: PocketMine 32bit?

Sat Sep 02, 2017 2:16 pm

I haven't fully checked, but I looked at the install of PocketMine-MP for the Pi and it seems to still be 32 bit.

jahboater
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Re: Raspbian Stretch not 64bit?

Sat Sep 02, 2017 2:45 pm

DirkS wrote:
Sat Sep 02, 2017 1:28 pm
No, it's still 32-bit.
And it's unlikely there will ever be an official RPF 64-bit release. Basically too much effort for very little (or no) gain.
Not for the Pi3.
But I speculate that the Pi4 in the future will have more memory and may require a 64-bit OS, as similar boards do now.

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Re: Raspbian Stretch not 64bit?

Sat Sep 02, 2017 3:34 pm

Providing a 64 bit OS would mean there would be 2 variations of the OS and many applications would also have to have a 32 bit and 64 bit version to get the performance you are expecting. This may add some confusion to owners of older Pis that are 32 bit. This move would almost double the amount of work for the RPF and application contributors. Form experience with Windows most applications would not benefit from such a move. Only high end graphic editors and intensive data processing applications would benefit the most.
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Re: Raspbian Stretch not 64bit?

Sat Sep 02, 2017 3:38 pm

nematode wrote:
Sat Sep 02, 2017 1:24 pm
I thought raspbian stretch was 64bit. I installed it on my pi3 hoping to use PocketMine-MP (32bit no longer supported). However, it still says 32bit no longer supported and the command getconf LONG_BIT returns 32. Is raspbian ever going to go to 64bit?
Fedora/Centos ARM64 are available ;)
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Re: Raspbian Stretch not 64bit?

Sun Sep 03, 2017 9:50 pm

gkaiseril wrote:
Sat Sep 02, 2017 3:34 pm
Providing a 64 bit OS would mean there would be 2 variations of the OS and many applications would also have to have a 32 bit and 64 bit version to get the performance you are expecting. This may add some confusion to owners of older Pis that are 32 bit. This move would almost double the amount of work for the RPF and application contributors. Form experience with Windows most applications would not benefit from such a move. Only high end graphic editors and intensive data processing applications would benefit the most.
How?
The SOC is capable of 64bit and 32bit on all Pi models. Literally the only extra work would be 64bit optimisation of the OS and to put on the download page "32bit download, 64bit download"

Infact, if they go 64bit, is there any point in keeping the 32bit OS at all?
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Re: Raspbian Stretch not 64bit?

Sun Sep 03, 2017 10:02 pm

We still sell 32 bit devices, the earlier models AND the Pi Zero. If we went 64 bit only that leaves those machines out in the dark! Which would be completely stupid.

And its not just an recompile/optimisation, it is CONSIDERABLY more complicated than that, or don't you think we would already be doing it? Even now, a fully working 64bit version with all the VC4 interfaces working correctly (The VC4 is 32 bit....) hasn't been completely sorted out.
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Imperf3kt
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Re: Raspbian Stretch not 64bit?

Sun Sep 03, 2017 11:00 pm

I understand it is a lot more work that "simply optimise it" but wouldn't it be more appropriate to focus efforts on improving the future of the Pi rather than supporting deprecated devices indefinitely?
Those devices will still work, just won't get further updates / fixes.

And the older Pis are only 32bit? I read somewhere in the FAQ that the SOC was supposed to be capable of both 64bit and 32bit?
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W. H. Heydt
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Re: Raspbian Stretch not 64bit?

Sun Sep 03, 2017 11:25 pm

Imperf3kt wrote:
Sun Sep 03, 2017 9:50 pm
How?
The SOC is capable of 64bit and 32bit on all Pi models. Literally the only extra work would be 64bit optimisation of the OS and to put on the download page "32bit download, 64bit download"

Infact, if they go 64bit, is there any point in keeping the 32bit OS at all?
Pi0, Pi0W, A+, B+, CM, plus older Pis (Model B, Model A, Pi2B v1.1) are incapable of running in 64 bit mode.

I can see two *possible* ways that Raspbian might go to 64-bit. The first would be if all other "lines" of Pis get an SoC that can run 64-bit code. The CM is already there (CM3, CM3L). At some point there is supposed to be a Pi3A, which would take care of that series. The remaining issue is then the Pi0/Pi0W. There isn't a path for those to get a 64-bit capable SoC at this time. Even of all Pi model types could run 64-bit, it still wouldn't happen for some years. Basically until the 64-bit capable models completely dominated what is in use and 32-bit only could be deprecated.

The other pathway would be to maintain 2 versions of Raspbian. That is also very unlikely until most Pis in use can use 64-bit.

TL;DR: maybe someday, but don't hold your breath while waiting.

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Re: Raspbian Stretch not 64bit?

Sun Sep 03, 2017 11:31 pm

W. H. Heydt wrote:
Sun Sep 03, 2017 11:25 pm
Basically until the 64-bit capable models completely dominated what is in use and 32-bit only could be deprecated.
...
TL;DR: maybe someday, but don't hold your breath while waiting.
That would effectively make 10 of my 14 RPis unusable.

The answer is to go with Fedora 64-bit and leave Raspbian running 32-bit. There's a blog about it from a year ago.
http://fc24-rpi.blogspot.co.uk/2016/09/ ... 24-on.html

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Re: Raspbian Stretch not 64bit?

Sun Sep 03, 2017 11:47 pm

Imperf3kt wrote:
Sun Sep 03, 2017 11:00 pm
I understand it is a lot more work that "simply optimise it" but wouldn't it be more appropriate to focus efforts on improving the future of the Pi rather than supporting deprecated devices indefinitely?
Those devices will still work, just won't get further updates / fixes.

And the older Pis are only 32bit? I read somewhere in the FAQ that the SOC was supposed to be capable of both 64bit and 32bit?
There are two different SOCs on current Pis, the original single CPU 32bit one on Pi0, A+, B+ (and older versions) and the quad CPU 32/64bit one on new 2B and 3B, plus a third (quad CPU 32 bit) on older Pi2Bs.

The development of new SOCs for Pis (and all other Pi developments so far) ensured backwards compatibility -- any current Pi image will run on any Pi hardware. This despite changes to memory mapped hardware addresses, GPIO assignments, and other necessary changes.

No Pi model has yet been "deprecated", they are all still supported. Obviously that will not continue for ever, but it is the story now (note that the oldest retail Pis are less than six years old). So supporting the older models (and the currently available 32bit only versions) is not optional, but essential.

Third party 64bit OSs are beginning to appear. No doubt soon we will be able to test their advantages and the circumstances in which 64bit code actually runs faster (I think I've seen one report here so far).

I don't know for certain, but I would be surprised if it was a simple choice between continued 32bit support and developing a 64bit OS. We just won't know until it's ready. I expect someone estimated the effort required and determined that resources were not available pre-Stretch -- well now Stretch is here and is being worked on to eliminate the early problems. I don't know what other projects are competing for resources. We do know that a new model (hardware) will appear at some time, and may or may not be radically different under the hood. It may or may not be possible to retain backwards compatibility. We do know that the elves in Pi Toweras are busy (read jamesh's posts). We don't know what will appear when (even the "announced" Pi3A has not landed yet).
If I had to guess, I would go for products in this order: Pi3A, Pi4, 64bit OS. No guesses for when. There may be other surprises. We live in interesting times.
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Re: Raspbian Stretch not 64bit?

Mon Sep 04, 2017 12:15 am

There would be millions of Pi owners left stuck with what they have at the time if the Foundation dropped 32-bit and went entirely 64-bit. I don't think that would feel acceptable to the Foundation for many years to come seeing as any Pi's which may become redundant when new models are purchased are quite likely to trickle down to the people who can least afford and could benefit most from Pi's.

I suspect there is also an understandable reluctance to embrace 64-bit lest that leads to software not being available for users of older Pi's. Sometimes it's inevitable but I think most of us hate it when told we must buy new hardware, install a new OS, just to run someone's software because they won't support older models and versions, effectively making what we have obsolete though otherwise perfectly serviceable.

An alternative to wishing the Foundation goes 64-bit is the option of encouraging software developers to continue supporting 32-bit.

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Re: Raspbian Stretch not 64bit?

Mon Sep 04, 2017 12:30 am

Thank you all for the patient explanations. That cleared up a few misconceptions of mine.
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W. H. Heydt
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Re: Raspbian Stretch not 64bit?

Mon Sep 04, 2017 12:54 am

DougieLawson wrote:
Sun Sep 03, 2017 11:31 pm
W. H. Heydt wrote:
Sun Sep 03, 2017 11:25 pm
Basically until the 64-bit capable models completely dominated what is in use and 32-bit only could be deprecated.
...
TL;DR: maybe someday, but don't hold your breath while waiting.
That would effectively make 10 of my 14 RPis unusable.
I think my proportions are worse than that, since I still run a fair number Pi2Bv1.1 units. It is, however, why I phrased my opinion the way I did. I don't expect to see 64-bit Raspbian as a main OS for at least 5 years, and quite possibly not for 10 (which translate to maybe not in my lifetime).

Edit to add... It occurs to me to point out that the CM (which is 32-bit only) has a commitment to remain in production through 2022, so 32-bit Raspbian has be around well past that.

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Re: Raspbian Stretch not 64bit?

Mon Sep 04, 2017 8:12 am

W. H. Heydt wrote:
Mon Sep 04, 2017 12:54 am
I don't expect to see 64-bit Raspbian as a main OS for at least 5 years, and quite possibly not for 10 (which translate to maybe not in my lifetime).
Obviously they have to retain 32-bit Raspbian for a long time to come.
But what about the Pi4 when it comes? Although 32-bits can in theory address up to 4GB, I believe other SBC's with 2GB had to go 64-bit because of something strange about the ARM's addressing or memory mapped peripherals. So iff the Pi4 has 2GB or more then providing a 64-bit Raspbian may be a necessity. </speculation>

Although there are several 64-bit distros for the PI, I doubt if any of them are as good (for the Pi) as Rasbian.

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Re: Raspbian Stretch not 64bit?

Mon Sep 04, 2017 4:34 pm

jahboater wrote:
Sat Sep 02, 2017 2:45 pm
But I speculate that the Pi4 in the future will have more memory and may require a 64-bit OS, as similar boards do now.
Not unless it has more than 4GB or RAM...which is to say, Highly Unlikely. (And even then, it wouldn't necessarily *require* a 64-bit OS. It could just leave the memory above 4GB unused.)

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Re: Raspbian Stretch not 64bit?

Mon Sep 04, 2017 5:28 pm

W. H. Heydt wrote:
Mon Sep 04, 2017 4:34 pm
jahboater wrote:
Sat Sep 02, 2017 2:45 pm
But I speculate that the Pi4 in the future will have more memory and may require a 64-bit OS, as similar boards do now.
Not unless it has more than 4GB or RAM...
No, I think 2GB is the limit because of something peculiar about its addressing or memory mapped peripherals - I cant remember the details. That was the reason given why the Pine64 and Odroid C2 (both with 2GB ram and the same Cortex-a53 CPU's) had to have 64-bit OS's. This Broadcom SoC may be different I suppose.
W. H. Heydt wrote:
Mon Sep 04, 2017 4:34 pm
(And even then, it wouldn't necessarily *require* a 64-bit OS. It could just leave the memory above 4GB unused.)
Likely true. But I cant see people being very happy about that!

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Re: Raspbian Stretch not 64bit?

Mon Sep 04, 2017 7:08 pm

jahboater wrote:
Mon Sep 04, 2017 5:28 pm
W. H. Heydt wrote:
Mon Sep 04, 2017 4:34 pm
jahboater wrote:
Sat Sep 02, 2017 2:45 pm
But I speculate that the Pi4 in the future will have more memory and may require a 64-bit OS, as similar boards do now.
Not unless it has more than 4GB or RAM...
No, I think 2GB is the limit because of something peculiar about its addressing or memory mapped peripherals - I cant remember the details. That was the reason given why the Pine64 and Odroid C2 (both with 2GB ram and the same Cortex-a53 CPU's) had to have 64-bit OS's. This Broadcom SoC may be different I suppose.
Or, possibly. the PINE64 people didn't do their own OS and the chip maker (who are likely to have done the base work) were too lazy and/or not paid to make the effort didn't even try for a 32-bit OS. Also--IIRC--the PINE 64 kernel is rather old. Much older than the Raspbian kernel was when the PINE64 was actually delivered.
W. H. Heydt wrote:
Mon Sep 04, 2017 4:34 pm
(And even then, it wouldn't necessarily *require* a 64-bit OS. It could just leave the memory above 4GB unused.)
Likely true. But I cant see people being very happy about that!
I'm not sure most people would even notice, and if they did, they could be pointed to another distro that would use all the RAM. On the whole, though, 4GB on a Pi4B is, I think, exceedingly unlikely. 2GB could probably classed as "possible". What I would (reasonably, I think) expect is that the SoC for the Pi4B will be *able* to address 2GB, and quite possibly considerably more, but in that case you won't see a Pi with maxed out RAM for quite some time. I'm thinking back to the 256MB Model B and the original proposal for 128MB on the Model A (though no actual Model A was ever on the market with less than 256MB).

jahboater
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Re: Raspbian Stretch not 64bit?

Mon Sep 04, 2017 7:25 pm

W. H. Heydt wrote:
Mon Sep 04, 2017 7:08 pm
I'm not sure most people would even notice, and if they did, they could be pointed to another distro that would use all the RAM.
Maybe. Then we would have a 64-bit processor that we cant run 64-bit software on and 2GB+ of ram that we can only use 1GB of. Seems a shame to me!
On the whole, though, 4GB on a Pi4B is, I think, exceedingly unlikely. 2GB could probably classed as "possible". What I would (reasonably, I think) expect is that the SoC for the Pi4B will be *able* to address 2GB, and quite possibly considerably more, but in that case you won't see a Pi with maxed out RAM for quite some time. I'm thinking back to the 256MB Model B and the original proposal for 128MB on the Model A (though no actual Model A was ever on the market with less than 256MB).
Yes I agree.

The trouble with all of this is that Raspbian is so very good, it is the best distro for the Pi, and its no good people saying "Oh well you can always use 64-bit OpenSuse or Fedora or Arch" ...

fruitoftheloom
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Re: Raspbian Stretch not 64bit?

Mon Sep 04, 2017 11:11 pm

https://wiki.debian.org/RaspberryPi3

https://www.debian.org/releases/stable/ ... -platforms

Would appear that quite a lot of development is needed and maybe by the time Buster is released Debian ARM64 may be an option ??
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tkaiser
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Re: Raspbian Stretch not 64bit?

Mon Mar 05, 2018 6:50 am

W. H. Heydt wrote:
Mon Sep 04, 2017 7:08 pm
Or, possibly. the PINE64 people didn't do their own OS and the chip maker (who are likely to have done the base work) were too lazy and/or not paid to make the effort didn't even try for a 32-bit OS.
Seems there is some confusion around this. :)

The Pine64 or better its SoC is limited to address 3GB DRAM (requires a physical 4GB memory configuration with 1GB wasted which is why no one is doing this so far and 2GB seem to be the maximum).

There's neither a need to run a 64-bit userland with 64-bit ARM SoCs nor is there a memory barrier that would require switching from 32-bit to 64-bit once a certain amount of memory is used as long as 4GB aren't exceeded (then you need a 64-bit kernel but can still combine this with a 32-bit userland). In fact the vendor offerings (that's usually Android and not Linux) for almost all currently available 64-bit SoCs are 32-bit only for a very simple reason called memory constraints.

64-bit software eats up more DRAM due to larger data structures. This is especially important on systems that lack huge amounts of DRAM (like e.g. Raspberry Pi). The issue is both well known (see vendor OS offerings with 32-bit Android userland) and gets ignored by a lot of people. See the excitement to run 64-bit server software for no reason: https://github.com/nodesource/distribut ... -290440706

With this specific workload the same performance is achieved but the 64-bit userland consumed 663MB memory while running 32-bit needs just 363MB. From this point of view running a 32-bit userland on 64-bit SoCs starts to make a lot of sense (if interested in this there's a bit more here: https://github.com/armbian/build/issues/645 )

Given the low physical memory available on RPi boards and that the proprietary VC4 stuff is 32-bit only there's not much you would gain switching to 64-bit other than being able to run less software at the same time. Though there's a few software out there that benefits from using the more modern ARMv8 ISA (it's not about 32-bit vs. 64-bit but about Raspbian building everything 'optimized' for ARMv6 while the SoC on the faster Raspberries can run ARMv8 software). For example the totally useless 'sysbench' cpu test when built for ARMv8 runs approx 15 times faster compared to an optimized ARMv6 version: https://github.com/bamarni/pi64/issues/4

So with a 64-bit distro you get one pseudo benchmark executing 15 times faster, other software maybe running 10%-15% faster but have compatibility issues with the VC4 stuff and run into memory issues sooner. On other 64-bit ARM platforms (eg. ODROID-C2 or Pine64) a common work-around some time ago was to install 32-bit binaries for web browsers since the 64-bit variants crashed sooner or later since running out of memory. So the proposed workaround was to do something like this on the 64-bit Linux distros used there

Code: Select all

dpkg --add-architecture armhf
apt-get install firefox:armhf
(see https://forum.pine64.org/showthread.php ... 1&pid=9515 -- in the meantime with Chromium it's not that much of an issue any more especially when we configure zram to squeeze a bit more out of the physical memory available. Works nicely with RPi too)

jahboater
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Re: Raspbian Stretch not 64bit?

Mon Mar 05, 2018 8:18 am

tkaiser wrote:
Mon Mar 05, 2018 6:50 am
For example the totally useless 'sysbench' cpu test when built for ARMv8 runs approx 15 times faster compared to an optimized ARMv6 version: https://github.com/bamarni/pi64/issues/4
It is specifically a 64-bit benchmark (for databases).

tkaiser
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Re: Raspbian Stretch not 64bit?

Mon Mar 05, 2018 10:29 am

jahboater wrote:
Mon Mar 05, 2018 8:18 am
tkaiser wrote:
Mon Mar 05, 2018 6:50 am
For example the totally useless 'sysbench' cpu test when built for ARMv8 runs approx 15 times faster compared to an optimized ARMv6 version: https://github.com/bamarni/pi64/issues/4
It is specifically a 64-bit benchmark (for databases).
I'm not talking about the sysbench modes to test for storage or database performance. Only the 'cpu' test is flawed since calculating prime numbers inside the CPU caches which is then not a hardware benchmark any more but just a compiler benchmark. A benchmark which scores improve by upgrading the distribution (Wheezy numbers are lower than Jessie, Jessie numbers lower than Stretch -- all just due to different GCC versions the binary has been built with) is not testing the hardware :)

And as already shown: simply by using the sysbench binary from an arm64 userland (that has been built with ARMv8 optimizations enabled!) results in execution times that are 15 times lower. This is not a hardware benchmark but a compiler benchmark. And of course your databases won't be that faster with an arm64 userland :)

jahboater
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Re: Raspbian Stretch not 64bit?

Mon Mar 05, 2018 12:11 pm

tkaiser wrote:
Mon Mar 05, 2018 10:29 am
I'm not talking about the sysbench modes to test for storage or database performance. Only the 'cpu' test is flawed since calculating prime numbers inside the CPU caches which is then not a hardware benchmark any more but just a compiler benchmark.
Yes indeed.
In this case it is using division for the prime numbers - and ARMv6 does not have a divide instruction.

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