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Re: [alpine-user] What is the best install type for embedded projects on the Raspberry Pi Zero?

From: Paul Zillmann <p.zillmann_at_h6g.de>
Date: Mon, 20 May 2019 12:41:20 +0200

Hello East,

loadable Kernel modules are stored in /lib/modules and don't have to be
in the in the /boot/ folder like in FreeBSD. If that would be the case,
you can easyli mount a folder onto another (mount bind).

Same is true for mounting a fat32 formatted partition (/dev/mmcblk0 if
I'm not mistaked) to /boot/ if you are used to work with the Linux
Filesystem Structure.

I'll take a look into the wiki.

- Paul

Am 19.05.19 um 13:54 schrieb East:
> Hello,
>
> I am working on a project that I want to use Alpine as the base for,
> however I am running into problems with resource usage. Specifically,
> I have limited constraints on RAM. Normally, a diskless install just
> loads everything into memory. Now, that may work for some platforms,
> but I only have 512MB of RAM, and I need to install relatively large
> dependencies and an X server. 512MB goes by fast.
>
> Normally, I would just do a sys install. The problem is, this is
> complicated on the Pi 1/Zero. From here
> <https://wiki.alpinelinux.org/wiki/Raspberry_Pi#Traditional_disk-based_.28sys.29_installation>:
>
> "Beware, though, that *the contents of /boot will be ignored when the
> Pi boots*: it will use the kernel, initramfs, and modloop images from
> the FAT32 boot partition. To update the kernel, initfs or modules, you
> will need to manually (generate and) copy these to the boot partition
> or you could use bind mount so that manually copy the files to boot
> partition is not needed."
>
> I am dealing with relatively low level stuff, and while I can't be
> sure, having the kernel and other core components not existing on the
> same partition as the rest of the filesystem is likely to cause
> problems. For example: how do I enable I2C with a setup like that?
> IIRC that requires a kernel module to be enabled, and if the wiki is
> to be believed, then that means I have to copy over files to the FAT32
> partition if I do that. It just seems messy, and that is a headache I
> would like to avoid. It also throws a wrench into the works when--once
> I finally have a way to build the images that I will ship--this kludgy
> method randomly breaks.
>
> Maybe I am misunderstanding this. Nonetheless:
>
> How exactly does diskless mode work? I know that it loads everything
> into RAM, but if I create an APKOVL and then use it to store state,
> that loads everything into RAM on boot, right? Is there a way to
> reduce the RAM footprint by only loading the Alpine base into RAM,
> while storing the contents of the APKOVL on disk? If so, that is the
> most convenient solution.
>
> Is there a better way to handle a sys install on RPi Zero than is
> documented in the wiki?
>
> Is there a better way to achieve this, period?
>




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Received on Mon May 20 2019 - 12:41:20 UTC