from Hacker News

Booting embedded Linux in 0.37 seconds on an ARMv7-A CPU at 528 MHz

by eerimoq on 6/17/20, 9:15 PM with 83 comments

  • by nimish on 6/18/20, 2:27 AM

    One interesting reason there's a been a bunch of progress in this space is that automotive systems are required to show the rear view camera in a certain amount of time. Progress driven by the oddest of things.
  • by ndesaulniers on 6/17/20, 11:37 PM

    I'm impressed. I don't know of too much work that's going on upstream for optimizing boot times, other than some of the clear linux stuff: https://www.phoronix.com/scan.php?page=news_item&px=Clear-Li...

    There are folks looking into improving boot times on Android; turns out init and kernel drivers are a tangly mess of {dependency} spaghetti. Loading kernel modules can induce delays in processing relocations.

    The kernel patches disable a bunch of stuff, including ethernet it looks like? Most of the kernel changes comment out blocks of code, or trade long delays for shorter delays with more iterations.

  • by Polylactic_acid on 6/18/20, 2:27 AM

    Does anyone know why x86 systems are so slow to start up? I got a x570 mobo recently and it still takes about 5 seconds to get to grub.
  • by WatchDog on 6/18/20, 12:22 AM

    > Networking takes by far the longest time to get ready. The main reason is that Ethernet auto-negotiation takes a significant amount of time, about 1 to 3 seconds.

    Is this a fundamental limitation of how auto-negotiation works? Is there a way to speed it up?

  • by yjftsjthsd-h on 6/17/20, 10:55 PM

    > A reboot is even faster, only 0.26 seconds from issuing the reboot to entering user space.

    Curious; it doesn't say how that works. Could be kexec, but if it's a real reboot then I'd be interested to know why it's faster. Can you still skip some hardware initialization somehow?

  • by dmitrygr on 6/18/20, 6:37 AM

    > Start with MMC clock frequency at 52 MHz instaed of 400 kHz.

    Whoa there!

    Spec violation. Not guaranteed to work. Might work some days but not others.

  • by m463 on 6/20/20, 12:27 AM

    I have an intel system that takes 20x as long just to beep that there's no keyboard.
  • by Yanu-3452 on 6/18/20, 8:28 AM

    Are super-quick boots vulnerable to having a (presumably?) lower entropy pool exploited or do the steps taken to mitigate low entropy across freshly minted cloud images also help here?
  • by pcdoodle on 6/18/20, 3:17 PM

    The hardware looks awesome! Looks like it hasn't been updated in 2 years though, has anyone produced these PCBs based on the Jiffy?

    Is that an EMMC Socket on there?

  • by eximius on 6/18/20, 3:26 AM

    Why can't network boot up be done asynchronously?