[Pkg-sysvinit-devel] Bug#691673: initscripts: please, allow having /run *not* being a RAM disk.

[Roger Leigh]

On Sun, Oct 28, 2012 at 12:18:25PM +0000, Roger Leigh wrote:
> On Sun, Oct 28, 2012 at 10:02:57AM -0200, Rogério Brito wrote:
> > For those people that want to shoot themselves on their own foot, please
> > allow (even if undocumented) running with /run *not* being a ramdisk.
> > 
> > This is especially important for memory-starved machines like embedded
> > computers/NASes, where every single byte of RAM is important.
> 
> We aleady do allow this.  Just comment out the
> mount_run and mount_lock lines in /etc/init.d/mountkernfs.sh.
> We allow RAMLOCK to turn off /run/lock; we don't expose a
> RAMRUN to allow /run to be turned off--you do need to edit
> the script directly.
> 
> The bootclean logic for cleaning /run still exists, so it
> will continue to work without it being a tmpfs.
> 
> However... note that this would be done *entirely* at the
> user's risk.  The reason for making /run a tmpfs unilaterally
> was mainly so that it could be relied upon to *be* a tmpfs,
> and so software can therefore assume that a tmpfs is present.
> This is primarily so that software services started in the
> initramfs can retain their state and open files from early
> boot through to the running system.  Examples: udev, mdadm.
> While these also have codepaths to allow booting in the
> absence of an initramfs, it is possible that in the future
> these or other services will require a tmpfs.

Related to this: if you use an initramfs, the initramfs will
mount the tmpfs; initscripts is not involved other than to
adjust the size limits.

By the way, the size requirements for /run should be tiny.
On a desktop system with quite a lot of stuff running, it's
600KiB.  On a small system doing only a small number of
tasks, it should be just 10s of KiB--i.e. it should not
use much memory at all, and if you have a swap device it
will be swapped out if needed.


Regards,
Roger

-- 
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