Subject: Re: [alpine-user] What is the best install type for embedded projects
 on the Raspberry Pi Zero?
To: alpine-user@lists.alpinelinux.org
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From: Paul Zillmann <p.zillmann@h6g.de>
Message-ID: <c5adcf57-d655-edfb-0cab-b2f0013edce3@h6g.de>
Date: Mon, 20 May 2019 12:41:20 +0200
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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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    Hello East,<br>
    <br>
    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).<br>
    <br>
    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.<br>
    <br>
    I'll take a look into the wiki.<br>
    <br>
    - Paul<br>
    <br>
    <div class="moz-cite-prefix">Am 19.05.19 um 13:54 schrieb East:<br>
    </div>
    <blockquote type="cite"
cite="mid:d06_bEhSwo8vB2g-WhHUr4G1jMRhvNEwtXELbRqSaAev1pcShdFV88-QZLX-8M1C3qTSW8Dxl6wfp_h8R4xxHOpOpl1cQ5lGdN0eVhGfP4U=@protonmail.com">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      <div>Hello,<br>
      </div>
      <div><br>
      </div>
      <div>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.<br>
      </div>
      <div><br>
      </div>
      <div>Normally, I would just do a sys install. The problem is, this
        is complicated on the Pi 1/Zero. From <a rel="nofollow"
title="https://wiki.alpinelinux.org/wiki/Raspberry_Pi#Traditional_disk-based_.28sys.29_installation"
          target="_blank"
href="https://wiki.alpinelinux.org/wiki/Raspberry_Pi#Traditional_disk-based_.28sys.29_installation"
          moz-do-not-send="true">here</a>:<br>
      </div>
      <div><br>
      </div>
      <div>"Beware, though, that <b>the contents of /boot will be
          ignored when the Pi boots</b>: 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."<br>
      </div>
      <div><br>
      </div>
      <div>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.<br>
      </div>
      <div><br>
      </div>
      <div>Maybe I am misunderstanding this. Nonetheless:<br>
        <br>
        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.</div>
      <div><br>
      </div>
      <div>Is there a better way to handle a sys install on RPi Zero
        than is documented in the wiki?<br>
      </div>
      <div><br>
      </div>
      <div>Is there a better way to achieve this, period?<br>
      </div>
      <div><br>
      </div>
    </blockquote>
    <br>
  </body>
</html>

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