[Buildroot] swapoff, but no swapon in initab

Arnout Vandecappelle arnout at mind.be
Wed Jun 20 20:13:12 UTC 2018

On 20-06-18 10:42, Peter Korsgaard wrote:
>>>>>> "Arnout" == Arnout Vandecappelle <arnout at mind.be> writes:
>  > On 12-06-18 16:50, Peter Korsgaard wrote:
>  >>>>>>> "Arnout" == Arnout Vandecappelle <arnout at mind.be> writes:
>  >> 
>  >> >> But it does require people to add swapon/swapoff to their busybox config
>  >> >> even if they aren't using swap, otherwise they would get error messages
>  >> 
>  >> >  I think if people start customizing the busybox config and remove stuff from
>  >> > it, then it's only reasonable that they also modify the default
>  >> > inittab.
>  >> 
>  >> Correct.
>  >> 
>  >> > Swaponand swapoff are both enabled in our busybox.config and busybox-minimal.config.
>  >> 
>  >> Hmm, does swap work on nommu? I would guess not. Looking at the kernel
>  >> option:
>  >  Doesn't matter if it works or not; if the swapon executable exists, then the
>  > swapon in inittab will pass without error (if you don't have swap configured in
>  > fstab). Clearly, the swapon will fail if you indeed have swap enabled in fstab
>  > on a NOMMU system, but I don't think we have to protect against that situation,
>  > right? It will anyway also fail if you don't have swap enabled in the kernel.
>  > Just like mounting the ext2 rootfs will fail if you don't have ext2/3/4 enabled
>  > in your kernel...
> Yes, so the only minor issue is that we need to have swapon/swapoff
> enabled in busybox-minimal.config even though it isn't useful just to
> not get an error message during bootup/shutdown.

 Well, it currently _is_ enabled in busybox-minimal.config... Admittedly, this
adds almost 1KB to the busybox size so perhaps it should be removed from
-minimal. But the we probably should also remove swapoff from inittab. Hell,
perhaps we should do that anyway, since doing swapoff for reboot is utterly
useless IMO.


Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
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