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#26 2013-02-05 23:14:25

Mindstormscreator
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Registered: 2012-07-01
Posts: 165

Re: Should "Arch Linux" also include architectures beyond x86?

Personally I don't think having a few ARM-specific variant kernels in Arch-proper's repositories is that bad, I mean, there's already linux and linux-lts plus a ton of others in the AUR. At least, until a unified kernel emerges.

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#27 2013-02-06 01:34:55

kmihelich
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Registered: 2011-04-23
Posts: 8
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Re: Should "Arch Linux" also include architectures beyond x86?

Allan wrote:

Is that still going to be the case in the future?  I seem to remember support for providing a single kernel for multiple boards being added upstream - but could be making it up entirely...

That could be changing in the future depending on how that effort pans out, which at this point looks promising.  This does also depend on those platforms having mainline support, which is much easier to do now with DT.  However, that then depends on the devices having a new enough U-Boot in order to "properly" boot a DT kernel, otherwise we will need some creative trickery to do on-the-fly uImage dtb appending, or just leave it as a manual process and hope people remember.

The big "if" in all that is of course getting boards mainlined.  Most boards start life with a kernel that has been hacked to pieces by the chipset manufacturer, which requires a significant amount of work to get mainlined.  A few specific devices come to mind that are still on manufacturer-based code and/or require significant patching on top of mainline in order to have everything on the board light up.  It's a complex process, but it's getting much better.  At this point we have around 20 device/platform-specific kernels we maintain, so if unification becomes possible we'll be one of the first to adopt it.

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#28 2013-02-06 01:56:40

kmihelich
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Registered: 2011-04-23
Posts: 8
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Re: Should "Arch Linux" also include architectures beyond x86?

HalosGhost wrote:

If the boards are not yet standardized enough that the kernel can be easily used across multiple boards (the great majority, really), I don't feel like it makes sense for Arch-proper to add support to it.

The kernels are really a moot point in the big picture of merging support, and a unified kernel approach in the grand scheme of things is a mere nicety in the greater logistical problem to be solved in order for it to be a reality.  The core chipset features are standardized, along with the majority of onboard peripheral support, which means that in the more important area of general package binary availability we need only target the lowest appropriate common denominator to ensure compatibility.

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#29 2013-02-06 02:09:06

Allan
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From: Brisbane, AU
Registered: 2007-06-09
Posts: 10,367
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Re: Should "Arch Linux" also include architectures beyond x86?

And here in lies the issue...   Do we join and bring in the packages for ARMv5, ARMv6 or ARMv7?  Or the lot?   We do not have packages optimized for (e.g) Core-i7 in the repos.   Do we wait for ARMv8, which might be around for a while before v9 is thought about and also might be more appropriate for desktops - or at least low power servers?

And anyway, the ARM port is doing very well without being official Arch.   The need to merge under a single umbrella is limited.

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#30 2013-02-06 02:32:18

kmihelich
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Registered: 2011-04-23
Posts: 8
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Re: Should "Arch Linux" also include architectures beyond x86?

Personally, I find the separation somewhat appropriate in a way, most importantly in the infrastructure we've developed to be able to do what we do as well as we do it.  A number of Arch developers and TUs use and/or contribute in some way to the port as it is; there isn't as large of a chasm between the projects as one might imagine.  We maintain package parity, modifying only what needs to be to compile correctly, and promote the Arch philosophy.

I am interested in the input from the community on it all though, maybe someone sees something we don't.

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#31 2013-02-06 10:21:03

HalosGhost
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From: Twin Cities, MN
Registered: 2012-06-22
Posts: 1,485
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Re: Should "Arch Linux" also include architectures beyond x86?

kmihelich wrote:

if unification becomes possible we'll be one of the first to adopt it.

kmihelich wrote:

The kernels are really a moot point in the big picture of merging support, and a unified kernel approach in the grand scheme of things is a mere nicety in the greater logistical problem to be solved in order for it to be a reality.  The core chipset features are standardized, along with the majority of onboard peripheral support, which means that in the more important area of general package binary availability we need only target the lowest appropriate common denominator to ensure compatibility.

kmihelich wrote:

Personally, I find the separation somewhat appropriate in a way, most importantly in the infrastructure we've developed to be able to do what we do as well as we do it.

Well, I'm convinced. It sounds like you've got the operation pretty well-done and setup in what is, perhaps, the best way for now. (I'm actually very excited for ODROID-X2 support as it's one of the first devices which I've seriously considered purchasing.) If some kind of unification effort ever does happen, and it ever makes sense to merge ARM support into Arch-proper, that would be awesome, but it seems as though the current setup has few down-sides.

All the best,

-HG


"All errors are ᴘᴇʙᴋᴀᴄ errors—It's just a matter of narrowing down which keyboard and chair." -Trilby
\ldots

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#32 2013-03-23 21:30:52

GI Jack
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Registered: 2010-12-29
Posts: 85

Re: Should "Arch Linux" also include architectures beyond x86?

the big problem with ARM, is that unlike x86, you can't just build one kernel for all CPUs. the x86 isn't just a CPU, its a very tightly defined platform, that has taken great steps for backward compatibility, while ARM has not.

The histories of the two CPU types are the reason.

MOST of the x86s have been in the form of desktop computers, or more recently servers, with the same archecteture, and powering similar hardware, with a standard set of operating systems, notably targeting one in particular, to be used as the same function as general purpose computing.

ARM after the Amiga, has been the brains behind dozens of dissimilar devices, with diffrent bootloaders(equiv of bios), that have absolutely no need wtih compatibility with other ARM devices, on many dissimilar opperating systems, with otherwise dissimilar hardware, running entirely dissimilar software.

However as of Linux 3.8, a single kernel, that can run on many ARM chips has arrived. ARM is the fastest growing CPU class, and is rapidly approaching the same GP computing status as the x86. I think we should at least consider bringing support for ARM, and bringing the archmobile/archarm team into Arch Linux propper.

the focus of x86 of Arch Linux is because of there wide availability, easy to work on general compute archecture, and ARM is slowly starting to move into that role.

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#33 2013-03-23 21:51:08

kmihelich
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Registered: 2011-04-23
Posts: 8
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Re: Should "Arch Linux" also include architectures beyond x86?

GI Jack wrote:

the big problem with ARM, is that unlike x86, you can't just build one kernel for all CPUs. the x86 isn't just a CPU, its a very tightly defined platform, that has taken great steps for backward compatibility, while ARM has not.

ARM is backward compatible.  ARMv5 can run ARMv4 compiled code, ARMv6 can run v5 and before, v7 can run v6, v5, and earlier, and the upcoming v8 is the same.  ARM, like x86, is a very tightly defined platform for the core architectures and instruction sets.  All of this information is available in their technical documents freely accessible on their website to alleviate any confusion.

GI Jack wrote:

ARM after the Amiga, has been the brains behind dozens of dissimilar devices, with diffrent bootloaders(equiv of bios), that have absolutely no need wtih compatibility with other ARM devices, on many dissimilar opperating systems, with otherwise dissimilar hardware, running entirely dissimilar software.

For many years the standard ARM bootloader has been U-Boot on nearly every device out there; there is an incredibly broad level of compatibility.

GI Jack wrote:

However as of Linux 3.8, a single kernel, that can run on many ARM chips has arrived. ARM is the fastest growing CPU class, and is rapidly approaching the same GP computing status as the x86.

The 3.9 kernel is looking even better, and I'm currently testing a unified kernel with that on v7 platforms.  I would also have to say that ARM devices have already approached general computing status, and that happened years ago.  Many of our users switch to an ARM device to run their NAS-style software, media streaming, DNS, and similar daemons inside of 10W instead of powering the old 200-300W computer they had in the closet doing it before.  Even if you have to split the load between two or three devices, the power savings alone are still huge with minimal, if any, noticeable impact to usability, latency, or throughput.

I'm more than happy to answer questions about any of this, and it's appreciated if you don't just blatantly proclaim incorrect information such as no backward compatibility.  Hit up Google, or just ask instead. smile

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