Changes/ARM as Primary

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ARM as primary Architecture

Summary

Make ARM a primary architecture. Add armv7hl to the i686 and x86_64 as arches that we build and support. This will mean that all packages supported by the ARM architecture must build for ARM to be released. With the release of Fedora 19 we have deprecated support for software floating support (ARMv5tel sfp) so the only proposed addition to primary architectures is currently ARMv7 hardware floating point 32 bit support (ARMv7 hfp 32bit).

Owner

Current status

FESCo resolution: Build ARM on primary infrastructure. Whether it is released as a primary Fedora 20 or as 'Fedora 20 for ARM' depends on how well it fulfills release criteria and functionality criteria closer to release time (+5).

Detailed Description

The Changing IT landscape has started to focus on greener technologies as well as cheaper mass produced devices that allow for fully functional cheap devices for lower socio-economic areas and other markets like education and "makers". ARM SoCs have traditionally been the domain of embedded and mobile applications but are now finding their way into more traditional computing devices like desktop, notebook and server markets. Fedora ARM currently works on many different devices with wider support coming with each new mainline kernel release.

For this change we will enable armv7hl builds on primary koji, and compose arm trees as with the other primary architectures. Fedora has in the Phoenix data centre 96 quad core Calxeda EnergyCore server nodes. Some of these nodes will remain allocated to the arm secondary architecture koji instance for building updates for the current Fedora 18 and 19 releases. When Fedora 18 goes end of life the ARMv5 softfp nodes will able to be be reallocated to other tasks. Infrastructure has expressed an interest in testing and experimenting with some of its workloads on ARM, some are allocated to QA and some for releng. There is currently 24 nodes configured in primary koji ready to go as builders, there is the capacity to add up to 24 more when ARM becomes primary if desired.

The kernel is now a multi platform unified ARMv7 kernel supporting a number of SoCs with support expanding with each new upstream release. We build a base and LPAE variant similar to i686. There is an ARM specific (ARMv7 and aarch64) kernel maintainer working in collaboration with the Fedora kernel team. The releases are composed using the exact same tooling as used for the primary architectures. Disk images for development boards are generated by appliance-creator and the kickstarts live in spin-kickstarts, they take a similar format as the livecds on primary but are shipped as an OEM disk image, and like primary initial-setup is used to do final user configuration. Like primary pungi is used to generate an install tree, PXE install trees are created but current bootloaders don't support isofs so ISO images aren't currently created.

Benefit to Fedora

Enables Fedora to embrace the emerging world of ARM devices. There are currently servers and desktop like systems that can be used to run Fedora on. ARM systems use very little power, the OLPC XO 1.75 and XO-4 are all arm based. Calxeda and Marvell based servers are shipping today with a number of other ARM server platforms announced from other SoC vendors such as Texas Instruments. In the desktop sphere there's devices being announced or available like that HP Slate 21 AIO, the Samsung Google Chromebook, the ASUS transformer devices, the Trimslice, all of which either work or in time will work. There are also dozens of different dev boards, HDMI dongles and set top boxes that will be supportable in the Fedora 20 release cycle. There could be investigation at having tablet spins in the future but that is currently outside the scope of this change. We are enabling new devices in the Fedora kernel as support lands upstream, allowing us to have a large number of ARM systems that are affordable and can run Fedora. By adopting ARMv7 as a primary architecture we will be embracing the future like other distributions are doing.

Scope

Add armv7hl to list of arches for f20-build and future build tags in koji compose armhfp trees with i386 and x86_64. Requisite build hardware already exists in phx2 and is configured to work with mainline koji.

  • Proposal owners: change the arches in koji, import the matching ARMv7 rawhide builds into koji. Update Release Engineering scripts to automatically build armhfp trees along with i686 and x86_64.
  • Other developers: submit builds as normal, in the event of unexpected build failures liaise with the ARM Team to help debug and fix issues.
  • Release engineering: Will need to add armhfp to the release processes and make arm install trees and disk images with each milestone compose. Release Engineering are part of the team of people proposing the Change.
  • Policies and guidelines: armv7hl builds will be required to complete for builds to be successful in koji

Upgrade/compatibility impact

Systems running Fedora 18 or 19 should be upgradeable in the same way that x86 systems are.

How To Test

There are many different test vectors, most visible to developers will be that when they submit a build a armv7hl build happens also. Any supported ARM system should work as it does today for ARM as a secondary arch.

User Experience

User experience does not change. The only difference will be the path in which they use to download files from on the mirrors.

Dependencies

There are no special dependencies. Hardware in Phoenix is already installed, there are release engineering boxes for doing composing on, there is hardware available for QA use.

Contingency Plan

  • Contingency mechanism: (What to do? Who will do it?) if for some reason we fail horribly at migrating into primary we would go back to secondary, the fix would be removing armv7hl from the build arches by Release Engineering
  • Contingency deadline: Alpha
  • Blocks release? Yes

Documentation

No documentation.

Release Notes