[Gta04-owner] suggestions for rootfs

Jonas Smedegaard jonas at jones.dk
Tue Jan 31 23:02:26 CET 2017

Quoting H. Nikolaus Schaller (2017-01-31 19:57:24)
> Hi Jonas,
> > Am 31.01.2017 um 19:41 schrieb Jonas Smedegaard <jonas at jones.dk>:
> > 
> > Quoting Andreas Kemnade (2017-01-31 17:22:46)
> >> here are some ideas for rootfs.
> >> 
> >> 1. /etc/default/rcS
> >> FSCKFIX=yes
> >> 
> >> Well, no chance to press an y key on the gta04, so this at least 
> >> give some chances to have it booted.
> When is this needed? I could so far use the RS232 console to type the 
> y if needed.

It is needed when pre-mount routines detect disk corruption that is 
risky to repair, i.e. where you might want to make a backup before 
aggressively trying to fix the errors.  If you are at a terminal, it 
will prompt you if you wanna proceed, but just hangs if you are not at a 
terminal - e.g. a remote server or an embedded device like a phone (not 
in debug mode).

> > Only relevant when the package sysvinit-core is installed.  By 
> > default with both current and upcoming stable debian, systemd-sysv 
> > is installed instead, which does not use that hint - and in upcoming 
> > stable release the file is not installed at all by default (so 
> > ensure that automated tweaking scripts check existence of the file 
> > before editing!).
> > 
> > Beware that "not default" implies "less tested"!  It is close to 
> > impossible to avoid systemd on Debian nowadays: If you try, you will 
> > quite likely end up with a system running poorly tested code as init 
> > and _still_ load systemd code indirectly through e.g. the SSH daemon 
> > (unless you aggressively avoid well-tested tools and e.g. use 
> > dropbear for ssh).
> Basically we have a rootfs that must fit into the 512MB NAND flash 
> limitation (which is more like 450MB) and have something useable in 
> NAND flash for demos or as a fallback if there is no woking µSD 
> installed (which has none of these limitations).
> With stripping languages and manuals I was able to get a working NAND 
> partition filled by just 99% (incl. kernel modules) where you still 
> can run apt-get upgrade (IMHO the package list cache has grown very 
> much). With Debian 7 it was never a problem to fit it into NAND.
> So some questions related to Debian 9 to make the right decisions: how 
> much space does it need on a rootfs compared to Debian 8.7? Has it 
> grown or did it shrink? Which one needs more space in rootfs: systemd 
> or sysvinit?

That obviously depends quite a lot on what you consider a "need".

At the work session I attended, I tried to trim your bootstrapping 
script, but you reverted that with the argument that e.g. development 
tools was quite handy to have available...

You can also remove /usr/share/doc - for a personally built system.  For 
a system distributed to others, all /usr/share/doc/*/copyright files 
must be preserved.  It is possible to instruct dpkg to automatically 
skip installing parts of the system, instead of installing fully and 
then removing again afterwards. I believe the package localepurge 
optionally trains dpkg, and I suspect it can be configured to also strip 
additional non-locale-related stuff.

 - Jonas

 * Jonas Smedegaard - idealist & Internet-arkitekt
 * Tlf.: +45 40843136  Website: http://dr.jones.dk/

 [x] quote me freely  [ ] ask before reusing  [ ] keep private
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