Ancestors

Written by Manawyrm | Sarah -> FOSDEM on 2024-09-01 at 21:22

New blog post:

Executing Linux applications on a Raspberry Pi in less than 3.5s from power-up! 🚀🏎️

(and other power saving tricks)

https://kittenlabs.de/blog/2024/09/01/extreme-pi-boot-optimization/

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Written by Marcus Müller on 2024-09-01 at 21:41

@manawyrm cool stuff! Have you tried with kernel compression through lz4, I.e., CONFIG_KERNEL_LZ4 ? Iirc, that beat the default gzip decompression very solidly in speed. You might also want to try _ZSTD, as I suspect the lower decompression speed of that might balance with the potentially higher compression ratio.

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Written by Manawyrm | Sarah -> FOSDEM on 2024-09-01 at 21:45

@funkylab I‘ve played around with kernel compression, but the extra energy required to decompress the kernel is harmful in my application.

In a less power constrained application, there might be some benefit, yeah!

A hardcore solution would be to write a custom minimal bootloader to move the kernel load away from the GPU and onto the CPU.

I‘m not that desperate yet, but it might help :)

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Written by Erin 💽✨ on 2024-09-01 at 22:53

@manawyrm @funkylab I'm guessing you tried U-Boot and it didn't help?

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Toot

Written by Manawyrm | Sarah -> FOSDEM on 2024-09-01 at 22:54

@erincandescent @funkylab U-Boot takes soo long to initialize and run that it just invalidates all benefit. I either need a brutally stripped down version or something custom.

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Descendants

Written by Manawyrm | Sarah -> FOSDEM on 2024-09-01 at 22:55

@erincandescent @funkylab U-Boot does things „the right way“, i kinda want something hacky. Let‘s assume all the peripherals are already up, don‘t validate anything, make some wild assumptions and just brutally load stuff from hardcoded addresses into memory.

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Written by Graham Sutherland / Polynomial on 2024-09-01 at 23:02

@manawyrm @erincandescent @funkylab this looks vaguely promising if not a bit of effort to get working

https://github.com/DOGSHITD/Simple-UEFI-Bootloader-ARM64

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Written by Marcus Müller on 2024-09-01 at 23:12

@gsuberland @manawyrm @erincandescent wait, there's no UEFI on the RPi, unless you teach it (e.g. by running U-boot)

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Written by Manawyrm | Sarah -> FOSDEM on 2024-09-01 at 23:15

@funkylab @gsuberland @erincandescent yeah, extra layers of glue code aren‘t really what I need.

There are several bare-metal projects like Pi1541 where I might be able to steal the toolchain + boilerplate from.

I‘m just not sure if it‘s worth the (engineering) time.

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