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As stated in the question's title - it's common knowledge that there are standards, according to which, if you format your pendrive, fitting there an x86 bootloader and a partition with the system, you can get an x86 USB stick that will pretty much boot on any computer. Are there similar standards for computers (like laptops) with ARM processors?

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  • Are you asking about Linux or any OS or kernel?
    – sawdust
    Mar 22, 2013 at 8:36
  • Most preferrably, any OS.
    – d33tah
    Mar 22, 2013 at 16:53
  • 1
    "...boot on any computer" -- You really mean "any PC which is based on the original IBM PC and its BIOS".
    – sawdust
    Mar 22, 2013 at 19:24

4 Answers 4

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There used to be a multi-paged document on "Booting ARM Linux". Unfortunately the web link to that document is now broken, but a copy seems to be here. That doc however did not specify or advise a specific bootloader or any file/data organization on boot media.

Items that I recall were things like the kernel should be linked to execute at the start of physical main memory + 0x8000.

ARM Linux also requires a list of various memory, board and machine parameters (known as ARM Tags or ATAG list) to be passed in a memory buffer to the kernel on boot. The bootloader would be responsible for constructing the ATAGs and the kernel command line in memory buffers. ATAGs apparently has been deprecated, and replaced by the Device Tree in newer Linux kernel versions.

The bootloader was also expected to setup and initialize RAM (which implies setup of clocks/oscillators), initialize one serial port or console, and detect the ARM machine type.

Note that most ARM SoCs employ a multistage boot sequence, and the bootloader that actually loads the Linux kernel is sometimes the third-stage bootloader.

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As of 2020, Arm SystemReady is the name of the overarching set of standards meant to “enable generic off-the-shelf operating systems”. For the booting standard specifically, that is the UEFI based Base Boot Requirements (BBR).

Arm SystemReady is a compliance certification program based on a set of hardware and firmware standards. These standards include the Base System Architecture (BSA) and Base Boot Requirements (BBR) specifications, and market-specific supplements.

Arm SystemReady replaces the successful Arm ServerReady compliance program and extends it to a broader set of devices.

The certification program comes in 4 variants (presumably for those “market specific supplements”):

  1. SystemReady SR (formerly Arm ServerReady)
    • This is where the previous standards SBSA and SBBR come from. These are still relevant, but supplemented by BSA and BBR.
  2. SystemReady ES (Embedded ServerReady)
  3. SystemReady IR (IoT Ready)
  4. SystemReady LS (LinuxBoot ServerReady)
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There are no standards. Every SoC vendor uses its own bootloader.

I have seen bootloader code from 3 major SoC vendors, and all 3 of them are different (use different internal data structures/etc).

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  • 3
    If you could add some context to your answers and/or provide some links it would make your answer more helpful
    – Shekhar
    Mar 21, 2013 at 22:57
  • @Shakehar, I have seen bootloader code from 3 major SoC vendors. All 3 of them are different (use different internal data structures/etc) - that much context I am willing to disclose. If you have more information - please post your own answer.
    – Alex P.
    Mar 22, 2013 at 0:38
  • 5
    I wasn't challenging your answer, the suggestion was just to improve the quality of answer by making it more informative for people who later on stumble upon this thread
    – Shekhar
    Mar 22, 2013 at 1:56
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The problem is described well in this document:

https://bootlin.com/pub/conferences/2017/lca/petazzoni-arm-introduction/petazzoni-arm-introduction.pdf

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