Arch Linux pulls the plug on 32-bit
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The rolling release aspect imposes to stay as close as possible to upstream versions because upstream does not wait on Arch to update their dependencies to newer libraries versions. This, plus the fact that Arch tries to stay as close as possible to vanilla upstream packages (i.e. less changes as possible), force them to be pragmatic about their choices. They prefer to embrace a change directly when it is happening, encouraging at the same time to contribute upstream for helping them make the transition, instead of trying to maintain a legacy compatibility that can only get worse with the time.
For me the picture is simple here: Arch is mostly used/oriented towards personal computers of power users, and most - if not all - of them are on 64 bit for years now. Instead of wasting efforts to maintain 32 bits compatibility, they prefer to drop it. Side effect will be that people will be encouraged to get a modern computer if not already.
All those netbooks (atom processors; 1 GB or 2 GB ram; 32 GB hard drive) would be great with Linux (once the drivers get fixed) and really benefit from 32 bit because of the ram limitations.
Now? They'll end up in landfill.
Of course, there's the Arch Linux Archive, which lets you sync packages as they were on a particular date.
A six-year-old 32-bit processor (e.g. an Atom in an EeePC 901 or HP Mini 311c) is more than capable of running a modern desktop system.
Also, for some of these machines they use a 32 bit UEFI, so even if you want to use a 64 bit OS you'll need some weird tinkering to get it installed.
I've successfully run Arch on a set of 10 EeePC 901s for a club. Linux plus Arduino programming = awesome kids.
I understand that some people would like to keep Arch 32 bit for their use cases. But as any open source project, the developer are mostly working on it on their spare time, you can not force them to work on anything. Having followed a little bit the discussion on the mailing list [1], I don't remember having seen a lot of objection among the developers. Also, they encourage the creation of a community around i686 [2]:
However, as there is still some interest in keeping i686 alive, we would like to encourage the community to make it happen with our guidance. The arch-ports mailing list and #archlinux-ports IRC channel on Freenode will be used for further coordination.
So if there are people willing to do the job, Arch will still be usable on 1686.[1] https://lists.archlinux.org/pipermail/arch-dev-public/2016-D... [2] https://www.archlinux.org/news/phasing-out-i686-support/
They come with a tiny bit of ram 2 gb, 4 gb if you're lucky.
The processor is 64 bit, but because of the small ram you'll suffer with a 64 bit OS. (Both Microsoft and Arch wiki agree here).
I suspect this means they'll end up in the landfill regardless.
Not installing python 2, and just python 3, with the name python3, would have been fine.
Arch put us in a situation where it was basically impossible to run python 2 with a #! line, as some distros hadn't yet introduced a 'python2' symlink yet.
But, don't make /usr/bin/python run python3, that just confuses programs which have made the (reasonable based on past experience, and official python advice) assumption that it /usr/bin/python will run python2.
It seems to me that the same approach could work for Python.
From the Arch developers point of view, the Python developers decided to release a new version of their language. They were going to support python 2 for a while, but the direction that the language was taking for the future was Python 3, so one day or another Python 3 would become the standard, so doing the switch was the good decision.
As said by @tbranyen the work of adapting shebangs have been done on the Arch side anyway, so I don't see a problem for people developing their projects in Python. Also Arch users are mostly power users (you need to understand quite a bit about linux to install it) so they are usually able to handle python 2 vs 3 errors quite well, especially as it is known than Arch use Python 3 by default.
They both contained Python scripts, and I had to waste my time figuring out why they had broken when I had e-mails from Arch users complaining they didn't work -- and then keep replying to future Arch users with the fix.
I don't know how many hours and days of other developer's time was wasted by Arch with this change, but it certainly wasted a good day of my time over the last few years.
"...however, end users should be aware that python refers to python3 on at least Arch Linux (that change is what prompted the creation of this PEP), so python should be used in the shebang line only for scripts that are source compatible with both Python 2 and 3..."
There was no guidance before the Arch devs made their choice. There's no reason to change back.
Especially since the goal is that python3 will be default eventually.
"...in preparation for an eventual change in the default version of Python, Python 2 only scripts should either be updated to be source compatible with Python 3 or else to use python2 in the shebang line."
Well, the answer is that this is a silly discussion. Arch is doing what Arch is doing because Arch is intentionally forward oriented, sometimes to the detriment of backwards compatibility with the old school (and yes, a distro not having a symlink for python2 is at this point nearly 5 years into being "old school").
Arch's change angered many in the Python community, and broke a lot of code. That Arch refuse to adopt the established convention, because it would involve admitting a mistake, shows a distinct lack of professionalism.
Well, until developers that do their work on other distributions start getting bug reports as a result of Arch's unexpected naming convention. Should someone outside of the distribution expect Arch to change so that their software works there? No. Should Arch expect outside developers to adapt their code to work on Arch? No. Honestly, I'd expect the kind of people that Arch attracts to be used to dealing with little snags in operation, and for them to just dive in and fix it on their own.
(Normally not a Windows user so I have no idea why this is the case or if by design.)
https://www.python.org/dev/peps/pep-0397/
As you say though, it doesn't rely on the names of the exes.
The reason we don't need a 'bash4' is that, by and large, bash tried very hard to make sure they didn't break any bash3 scripts, so there is no need for old bash3 scripts to know they are now running in bash4, unlike python3.
However, I can predict with near certaintly, if python 4 doesn't break python 3 scripts, people will complain if "python3" doesn't invoke python 4, because they've always used "python3" to run the new python and "python" to run python 2.
Personally, I'd rather just use `/usr/bin/env python2` to invoke the appropriate interpreter (if you don't need to pass arguments to it), and if the symlink doesn't exist, the onus is on the user to create it. This is ESPECIALLY true for older distros.
Plus, for a sufficiently complicated application, why would someone want to pollute the global site-packages anyway? I'd rather manage most things inside a virtualenv or similar (pick your Python version), because I've seen far too many install_requires/requirements locking to a specific library version.
While this is a small issue, this original thread used it as an example of how Arch is good and pragmatic. To me it seemed like the opposite -- it broke lots of code and packages for no good reason. Why should users of older distros have to add a symlink, when before Arch everyone could be sure that '/usr/bin/python' if present would be python2, and '/usr/bin/python3', if present, would be python3?
Now I agree that using virtualenv or similar is a good idea, but this actually caused the most problems for little 20 line python scripts, because often the users of those didn't even realise they were using python.
There was good reason, to move to the latest version of a particular software, since that's kind of the whole philosophy of Arch, in fact the reason I originally switched to it in 2011 was because I had enough of me not being able to use the latest software on Ubuntu.
> Why should users of older distros have to add a symlink, when before Arch everyone could be sure that '/usr/bin/python' if present would be python2
If you made no effort to detect the actual version, it's wrong to assume that. It could've just as well been python 1.
It's funny. My reason for switching to Arch was almost the opposite. I grew tired of having to rebuild the latest software in Gentoo every time I updated and ran into someone on Slashdot who encouraged me to give Arch a try. Sure, there's more prebuilt packages, mirrors, etc for Gentoo these days, but then you're in the same boat as everyone else (waiting for the package to be built).
I disagree. I don't believe it was as painful as some make it out to be. The official packages were updated within a relatively short period of time, and while the AUR packages took longer they're also not officially supported. There was also a news announcement [1]. Honestly, I think of a few other transitions over my years of using Arch as being far, far more painful. The Python2 -> Python3 defaults change isn't one of them.
Although I would agree that Gentoo's approach was somewhat better via eselect, which I believe predated Arch's migration.
> Why should users of older distros have to add a symlink
You're right. That should be the responsibility of the package maintainer. Conversely, why should I, as a developer, have to continue assuming `/usr/bin/python` points to any particular version of Python when most distributions have migrated away from this anachronism? sed does magic, and you really should be using the appropriate symlink for your desired version anyway. Python 3 isn't new. I have a hard time seeing this as problematic because 1) things change and 2) the solution is easy. I'd be happy to entertain a use case where this actually has presented material difficulties, however.
> but this actually caused the most problems for little 20 line python scripts, because often the users of those didn't even realise they were using python.
Well, I do agree: It's a problem for the end user, but the solutions aren't difficult (if someone's using Linux, they probably know enough to fix it). So, either change the hashbang, add a symlink, and--failing that--complain to the package maintainer if it's been packaged up by the distro and the upstream software itself has changed (it should).
My recommendation for developers would be to use the appropriate /usr/bin/python* symlink. Nearly all distros have them in place now (including Ubuntu from a couple years ago). Perhaps assuming /usr/bin/python will always point to a fixed version is a matter of misplaced assumptions.
Global site-packages is all fun and games until someone loses an eye (or a dependency).
I had a fun learning experience with a large Python package once while trying to mix and match dependency versions, simultaneously trying to avoid clobbering the ones already installed by pacman. Without a virtualenv, it quickly becomes impossible to guarantee you won't break something in the process of installing something else. I never made that mistake again.
As an aside first: I sometimes make a PKGBUILD for most things just on the merit that it's better for pacman to manage site-packages on its own--or anything, really. It's a terrible idea to stuff things into global library directories that aren't managed in general (although incautious use of things like npm or pip can certainly do that for you--still an awful idea).
However, I do recommend installing packages into a virtualenv for anything with modest complexity, because some applications have requirements/install_requires that lock specific versions which may not be mutually compatible with others, and there's also the circumstance where official packages aren't new enough but you still want the package manager to maintain the dependent package. I guess you could go with versioned packages in this case, but since the official ones will inevitably find themselves updated at some point, I see it as easier to circumvent the issue in the first place via a virtualenv.
Anyway, I did the above polluting nonsense once when building a package with quite a few dependencies: Trying to maintain a half dozen individual PKGBUILDs just for dependencies and pestering easily a half dozen other maintainers to update their respective PKGBUILDs versus modifying the application's setup.py (either with patch or sed) to match older versions were both terrible ideas and scaled poorly. It's far easier to simply build what's needed in a virtualenv and avoid polluting the global site-packages even with the package manager handling them on its own. This is especially true for complex applications with many dependencies that may already be installed (but with conflicting versions).
Sorry for the rant, you just reminded me and tickled all the right spots! :)
Because Bash was made by, and is maintained by, people who understand how backwards compatability in their program is important.
I get your frustration though, it's a change that breaks a whole lot of existing scripts.
You seem to be complaining because other distros hadn't done the right thing. I don't see how that's Arch's fault. Are we to hold back for the lowest common denominator? Do we need every distro to join together and agree to a switchover date?
There was official guidance from Python on the switchover, this wasn't some maverick decision. It was just moving forward.
Not everyone wants to be tied to ancient stuff for backwards compatibility - if you do, it's your job to deal with that.
from https://www.python.org/dev/peps/pep-0394/ (not yet replaced/update) "for the time being, all distributions should ensure that python refers to the same target as python2 ."
Because Arch did what they did, Python now recommends that Python 2 scripts start "#!/usr/bin/python2" (or the env equivalent).
> Are we to hold back for the lowest common denominator? Do we need every distro to join together and agree to a switchover date?
It's not just other distros; it's the rest of the world, including all of the scripts that people run but distros don't necessarily ship.
The right way to migrate would be to ship and use both /usr/bin/python2 and /usr/bin/python3. Leave /usr/bin/python as a symlink to python2 for a while. Eventually, drop the symlink, but do not replace it with python3. Allow users to opt-in to a compat symlink if they wish. Let stuff catch up. When the expectation that "python" is python2 has faded, then introduce a symlink from python to python3 by default, letting users opt-in earlier if they wish.
> There was official guidance from Python on the switchover, this wasn't some maverick decision.
No, there wasn't, and yes, it was some maverick decision. It was done without consultation with upstream.
(I am a non-Arch distribution developer)
So you made certain assumptions. Have you made your scripts use python2, which is safer anyway, everything would've been fine, don't blame Arch for your incorrect assumptions.
It was only because of what Arch unilaterally did that forced the community to start providing a /usr/bin/python2. Before that, /usr/bin/python2 did not commonly exist at all.
Arch is a bleeding-edge, latest software kind of distribution. They did not made the decision 'unilaterally'. They made the decision to ship the latest software for their own distribution, as they always do. It may have proven that a lot of software is extremely poor/inflexible, (i.e. rests on weak assumptions), but I am glad Arch moved forward as that showed their resolve to move technology forward even in the face of a lot of pressure from outside groups.
I just think that instead of blaming Arch, try to make your scripts more robust, i.e. loop on all 'python*' binaries in /usr/bin and use the first one whose --version gives you '2.x' instead of relying on /usr/bin/python being python 2 when the latest version is 3 and Arch is known to ship latest software.
As did all the other distributions. Shipping Python 3 is not the issue here. Breaking compatibility with all existing Python 2 scripts is what they did. The two are not mutually exclusive.
> I just think that instead of blaming Arch, try to make your scripts more robust, i.e. loop on all 'python<glob>' binaries in /usr/bin...
You want me to do that in a shebang line? No. That'd be crazy.
> ...when the latest version is 3 and Arch is known to ship latest software.
See https://en.wikipedia.org/wiki/Application_binary_interface. What Arch did was break the ABI of what /usr/bin/python means, breaking all scripts that relied on that ABI. Shipping the latest software is orthogonal to this. The rest of the world ships the latest software too, but without breaking ABI.
The ABI was never documented and at best a convention-enforced one.
I call your straw man. As I've already repeatedly said, the issue is about breaking ABI, not about what software distributions shipped, nor what they had installed by default. Making /usr/bin/python point to Python 3 has nothing to do with what distributions shipped, nor what they had installed by default. The issues are completely orthogonal. Stop trying to pretend otherwise.
> The ABI was never documented and at best a convention-enforced one.
Upstream shipped build systems that put Python 2 in /usr/bin/python, and Python 3 in /usr/bin/python3. That's about as good a definition of ABI as one gets in the free software world. Arch deliberately patched the ABI. You can try to argue that their decision to do so was correct, even though I disagree. You cannot argue that they didn't know they were changing an ABI when they patched the ABI.
But it is very much about that. Arch ships latest software, Python 3 is the latest python, python 2 is not. Ubuntu, Debian etc. ship old, outdated software regularly, Arch doesn't.
Because the latest python was python 3, /usr/bin/python pointed there. The other distributions explicitly decided not to ship the latest python.
Prior to Arch making the switch, the 'ABI' was not /usr/bin/python points to python 2, it simply pointed to the latest python release, which on most systems happened to be python 2, because they did not even ship python 3 at all at the time.
You may not agree with the decision, but to pretend like it was "out of nowhere" is unhelpful.
The idea that we should then never use `python` to mean `python3` is just so backwards. Sure, in your corporate environment where backwards compatability is suepr important, do that.
In Arch, people have a distro that moves fast and breaks things, and we are fine with that. I'll accept the cost of occasionally having to change a shebang line (although as I have almost never had to go outside the AUR - someone else in the Arch community has almost always dealt with this for me).
> No, there wasn't, and yes, it was some maverick decision. It was done without consultation with upstream.
Fair enough, I got my timelines mixed up - but to be fair, it was then ratified as the correct way to do things because the upstream project agreed with the core idea.
> The right way to migrate would be to ship and use both /usr/bin/python2 and /usr/bin/python3. Leave /usr/bin/python as a symlink to python2 for a while. Eventually, drop the symlink, but do not replace it with python3. Allow users to opt-in to a compat symlink if they wish. Let stuff catch up. When the expectation that "python" is python2 has faded, then introduce a symlink from python to python3 by default, letting users opt-in earlier if they wish.
I don't really see why I should have to do this manually? If you don't want that behaviour, use another distro. This just feels like you feel like you should have some say in how other people set up their systems.
If you really hate it so much, don't support Arch - that'd be fair. Trying to shame the distro for doing it ignores the fact it's the core idea of the distro to do stuff like that, that's the point.
I did not present any such idea. I presented a sane migration path to where `python` means `python3`.
> ...it was then ratified as the correct way to do things because the upstream project agreed with the core idea.
No. It was because the upstream project had their hand forced and are pragmatic about these things.
> I don't really see why I should have to do this manually?
In my proposal for a sane migration path to the ideal? You wouldn't have to do it manually. The distribution would do it. As a user you'd be able to override it to speed up the migration for yourself if you chose; that's all.
Expecting that is as weird as expecting super stable LTS releases to run the latest-and-greatest of everything.
Which part of "You wouldn't have to do it manually" do you not understand?
> In my proposal for a sane migration path to the ideal? You wouldn't have to do it manually. The distribution would do it. As a user you'd be able to override it to speed up the migration for yourself if you chose; that's all.
I want to speed up the migration for everything - that's why I run Arch. That 'override' is a manual step I don't want to have to do.
Well, the fact that over a decade after the release of python 3 we're _still_ arguing about it shows that lot of people think we should.
You don't need magical file-specific juju or a wrapper script on most systems these days to select the Python version. Just call python2 or python3 as appropriate; the symlinks usually exist depending on packager, distro, etc. The problem up-thread appears to be with calling the default `python` on $PATH. Sometimes it points to Python 2.x, sometimes it points to Python 3.x. Sometimes it might even change (Gentoo's eselect, IIRC). I don't see the problem being explicit with which version is needed in the script's hashbang. Python 3 isn't exactly new, and I remember when Gentoo and Arch both migrated to versioned symlinks. It wasn't that painful.
Also, the python2 symlink should have already been there. Bad packaging on some distros resulted in bad practices packaging by some devs. Don't blame that on Arch.
> Also, the python2 symlink should have already been there.
Nope. There was no such convention or specification at the time. There was, however, convention and specification (in the form of "what Python upstream build systems do") on what /usr/bin/python means, which is "Python 2".
There was no formal specification, but there was a convention that many distributions were already following (and quite a few others were not).
What. It was Arch who
* stuck to SysVinit and told users "you want Systemd, make a package" until long after the big distros had made the switch to Systemd/upstart (https://en.wikipedia.org/wiki/Upstart)
* refused to sign packages properly, because "our users don't need that"
It's exactly that kind of decision that makes me stay clear of it. They have the latest packages, but on the system side changes take way too long.
Suse was October 2014. Debian and Ubuntu were April 2015. RHEL was June 2014.
RHEL7 already dropped support for 32-bit hardware (although it still maintains the compat toolchain+libs for 32-bit binaries on 64-bit O/S).
I believe Windows Server 2012 similarly only runs on 64-bit hardware.
Also, I wonder what this means for the Intel Quark SoC (found in Intel Edison and Intel Galileo boards). Does this mean Arch Linux wont be an option for these devices?
Despite RHEL 7/CentOS 7 not supporting 32-bit x86, there is now a community-led effort to port it to 32-bit x86. I wonder if Arch would consider doing the same (supporting 32-bit x86 as an alternative architecture).
Yes: https://lists.archlinux.org/pipermail/arch-ports/2017-Januar...
(Also https://lists.archlinux.org/pipermail/arch-ports/2017-Januar...)
I have a T40p running Arch which I still occasionally use, even for development, because it's just such a pleasing machine ergonomically. So I'm a bit concerned about this as well -- but then, I've been happily using Arch for years and it's not like I've ever contributed anything to the effort of maintaining it.
You make a good point- I too have been an open-source consumer. Yea I have filed a few bug reports, helped some people experience Linux or switch from IE6 to Firefox, but have not contributed much to these projects time- or money-wise. With things like the Linux kernel, that are suported by the likes of Red Hat and SUSE (which are in turn supported by big businesses), I am not too concerned about their survival. But after reading about the GPG maintainer and now the GNU Octave maintainer being forced to stop their their generous contributions, I realize perhaps I need to be doing more as a user for open-source things I care about being around in the future.
> Also, I wonder what this means for the Intel Quark SoC (found in Intel Edison and Intel Galileo boards). Does this mean Arch Linux wont be an option for these devices?
I have a device based on the Quark SoC. Support is abysmal for this SoC, especially considering it's been on the market for 3 years (2014). Intel has clearly abandoned this market segment since their repeated headlines of new Quark SoCs has totalled exactly 0 new product launches since 2014.
In mainline Linux I can't use the onboard Ethernet because of some modifications Intel made to the stmmaceth module that weren't pushed upstream. The internet is full of people trying to run newer versions of Linux on their Quark hardware and Intel telling them to use old Yocto Linux BSPs [0] because they can't be bothered to clean up and push their code upstream (or upstream refused to merge it, I don't know and haven't checked).
Also the Quark is affected by the F0 0F bug, so you can't run normal distributions on it because processes will segfault. [1]
> It might solve this issue for Intel Quark, but it would break for any multicore processors. This is not something acceptable.
Honestly I'm not sure why anyone would want to buy a Quark based system. Support is bad, performance is terribad, and power consumption is also terrible (my Quark system idles at 7W, and consumes 2W when in S5 "off" state). You would be very wise to look for an ARM instead of choosing this dumpster fire of a CPU.
[0] https://communities.intel.com/thread/105047
[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=738575
As someone who owns a Raspberry Pi, PandaBoard, BananaPi, Orange Pi, and Intel DK200 I've learned this important life lesson:
Always assume that the most support you'll ever receive for the board is on the day you buy it.
Apart from the Raspberry Pi, no one else gives half a shit to fix bugs or even provide distro updates for their hardware.
Cheap Chinese boards are even worse for this. They'll typically take the SoC kernel (an ancient version several years out of date with the worst patches you've ever seen) and roll some shitty old distro around it (e.g. Ubuntu 14.04, Android 4.4).
A good recommendation for people looking to buy a board is to look at the Armbian [0] or Arch Linux ARM [1] supported hardware (read the notices!!!) and buy that.
You can boot other Linuxes on it (e.g. Yocto) but as per my parent comment, not much will work.
I have an SPI image and instructions to flash if you're interested. You'll need an SPI programmer like the ch341a.
I think Intel is violating the GPL by not providing sources, since they include a written offer and GPL requires source availability for 3 years.
I tried to download the WindRiver SDK using the code in the box, and Intel told me the product was no longer receiving support...
Really it's that nobody who is interested in 32-bit x86 support is prepared to maintain it. In Free Software land, that's almost always the reason that stuff gets dropped. If it's enough of a shame, those interested would step up and make it happen. They haven't.
We realized that some users do not (or cannot, due to security policies) turn on VT-x/AMD-V in their machines, and therefore Virtualbox and VMWare Player cannot run 64-bit guests.
So we had to make 32-bit virtual machine images for them. If popular distros stop supporting 32-bit, we will have a harder time packaging such images, since we'll have to use a different distro for them, with different package names, settings, etc.
Incidentally, wouldn't the exclusive use of 64-bit pointers (and size_t) prompted by the inflated need in large address spaces lead to an ever more increasing demand for memory (due to in-memory objects being now bigger in size)?
Yes. This is the reason why some people have pushed for "x32" support, and why Linux 3.4 and above supports it (tl;dr: x64-64, but with 32-bit pointers: you get all the advantages of x86-64 without the pointer bloat).
But wait. This could actually work out really well for Chrome, since it's multiprocess, and each process will likely consume <4GB.
That is really cool.
I've been wondering why Chrome on my T60 (64-bit but only 3GB RAM visible due to chipset stupidity) is noticeably, perceptibly slower and far more ready to swap itself to death than on my T43, which practically flies. (The T60 has a Core2 T7200, the T43 a Pentium M.) Bigger pointers sounds like a very interesting theory, especially considering the "enterprisey" nature of Chrome's C++ code - piles of vtables and pointers to pointers to callbacks to pointers to...
Arch isn't really meant to be that one distro you can stick on a PC from the early nineties anyway. There are much more suitable distros for legacy hardware.
And about the downsides of 64bit: I think the vastly improved address space offsets the improved memory use by orders of magnitues. My Desktop has 8 times as much useable RAM as it could have with 32bit - but 32bit datatypes are only double in size.
64-bit computers started gaining popularity in the consumer market only, what, 5 years ago?
Athlon 64 came out in 2003, Pentium 4F in 2005. I'll concede that 32-bit Atoms were reasonably popular in certain market segments, but hasn't generally every consumer computer been 64-bit for over 10 years?
Desktop CPUs have been basically guaranteed to be 64 bit since 2005.
The Pentium 3 derived Pentium M and Core Solo/Duo delayed wide mobile adoption of 64 bit until Core 2 came around in July 2006. I'd guess by 2007 you could probably safely assume 64 bit across all but the cheapest laptops as well.
tl;dr: Aside from a few Atom-powered netbooks 64 bit has been standard in anything resembling a normal computer for around a decade.
I still have that installed on a i386 machine, but not booted since years.
Did it even work usefully? While Linux itself retains backwards compatible drivers for a long time, X.org and others aren't quite as diligent.
E.g., five years ago I could not run any up to date distribution on Pentium 4 era notebooks with anything more than unaccelerated VESA framebuffers, because there were no compatible drivers for their integrated graphics card any more. (At the same time, we still had Pentium 4 servers in production use!)
The complexity of managing a secondary 32 bit environment has been worse than the memory usage of 64 bit apps for a very, very long time.
4GB max address space per process. It should support much more memory through PAE [1], which makes things more reasonable.
[1]: https://en.wikipedia.org/wiki/Physical_Address_Extension
* The stack is always kept aligned at 16 bytes boundary. This is needed for external calls by the ABI, but LTCG could drop these for internal calls and align the stack when needing SSE instead. This may be slightly more expensive than keeping the stack constantly 16-byte aligned, but it avoids wasting a lot of stack, so may very well be faster overall just by nature of less cache utilization.
* No push and pop, reserves needed stack space (even for function calls) in prologue and accesses stack with mov and lea instead. The full mov/lea instructions with mod/rm+sib takes up far more bytes that simple push and pop, but apparently it's faster.
* Inefficient instructions are replaced with more efficient instructions. For example gcc will for a simple x % 19 generate no less than 16 instructions instead of a single div/idiv. This is probably still faster, but it may still be detrimental if it's not in a hot path. It should be noted that gcc emits this even at -O0.
* Multiple versions of code copying, scanning or comparing arrays for handling different alignments. This seems quite stupid as there isn't even any penalty for unaligned accesses on modern x86 cpus except in some very specific circumstances[0]
These are all microoptimizations for getting the absolutely maximal performance out of tiny programs containing only hot code. However in reality programs rarely looks like that, and the increased code size and stack usage costs more than it gives. Profile guided optimizations is probably the way to go here, but distributed binaries have rarely if ever been compiled with PGO. Also I have no idea if PGO actually does drop these enlarging optimizations on non-hot codepaths on modern compilers.
[0]: http://lemire.me/blog/2012/05/31/data-alignment-for-speed-my...
Does it emit it at -Os ?
-O0:
main:
.LFB0:
.cfi_startproc
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset 6, -16
movq %rsp, %rbp
.cfi_def_cfa_register 6
subq $16, %rsp
movl %edi, -4(%rbp)
movq %rsi, -16(%rbp)
movl -4(%rbp), %ecx
movl $1808407283, %edx
movl %ecx, %eax
imull %edx
sarl $3, %edx
movl %ecx, %eax
sarl $31, %eax
subl %eax, %edx
movl %edx, %eax
sall $3, %eax
addl %edx, %eax
addl %eax, %eax
addl %edx, %eax
subl %eax, %ecx
movl %ecx, %edx
movl %edx, %esi
movl $.LC0, %edi
movl $0, %eax
call printf
movl $0, %eax
leave
.cfi_def_cfa 7, 8
ret
.cfi_endproc
-Os: main:
.LFB13:
.cfi_startproc
pushq %rax
.cfi_def_cfa_offset 16
movl %edi, %eax
movl $19, %ecx
cltd
movl $.LC0, %esi
movl $1, %edi
idivl %ecx
xorl %eax, %eax
call __printf_chk
xorl %eax, %eax
popq %rdx
.cfi_def_cfa_offset 8
ret
.cfi_endproc
So it kinda performs an optimization when disabling all optimizations that it doesn't do when optimizing for size. Or well, the default codegen is the optimized version. Interesting.I doubt Linux distros are generally targeting these devices, though.
> The Pentium D brand refers to two series of desktop dual-core 64-bit x86-64 microprocessors with the NetBurst microarchitecture, which is the dual-core variant of Pentium 4 "Prescott" manufactured by Intel.
https://www.freebsd.org/where.html 11-RELEASE and 12-CURRENT snapshots are still being published for i386!
Can anyone comment about their experiences with moving to Arch and the learning curve?
To me arch is designed to force you to learn the guts of your system, so it has a relatively high learning curve but it is one that pays dividends in the form of understanding what your system is doing and how it is setup. (this aside from the side-effect of keeping it debloated and therefor fast)
Honestly, what I would suggest is this:
Step 1:(if you have the time) go through a full arch install. Now format and do it again without following the guide. Now maybe do it one more time.
Step 2: (if pressed for time and/or lazy) Install Manjaro. I distro-hop frequently, and while I generally try to use debian on servers, for desktop/laptop use I have gone from Arch to Suse to Fedora, but I recently gave Majaro a shot, and I can honestly say next to Suse it has the easiest and most graceful linux installer I have ever seen (beating even Ubuntu). I generally don't like using Mint-like everything in a box distros, but the slimness of Arch along with the Just works of Ubuntu/Fedora/Suse I am finding it highly likely Manjaro is going to be my distro of choice for a long time to come. If in doubt, you can always just fire up different installs in a virtualbox first.
[1] Installing a 32-bit package on Debian uninstalls all 64-bit packages????????????????? Why is this even allowed?
Best simple/minimal install: use XFCE without a login manager. This gives you a very nice "default" environment without having to spend any time configuring.
Manjaro is a user-friendly Linux distribution based on the independently developed Arch operating system. Available in both 32 and 64 bit versions, Manjaro is suitable for newcomers as well as experienced Linux users.
see; https://manjaro.org/get-manjaro/
Or simply use "Manjaro Minimal Net Edition (32-bit)"
Another alternative is to use BlackArch (32-bit)
I'm sure Arch for what it is trying to be is user friendly in that sense, but it's not what I'm looking for right now.
I have a few 32 bit machines under my watch, and this is disheartening.
Bullshit, Arch was one of the first to switch to systemd as the default way back in 2012. The only "big distros" that switched before Arch were Fedora (obviously since that's where it came from), Mageia which is based on Fedora, and OpenSUSE (but not SLES). The next distro to switch was CoreOS a full year later, and Debian didn't switch until 2015.
I'm not a fan of Arch anymore either, but if you're going to disparage any distro, at least get your facts straight.
Edit: Getting my own facts straight: Mageia was based on Mandriva, not Fedora.