Bind mount can allow mount to be two places: >From the mount manpage:
" The bind mounts. Since Linux 2.4.0 it is possible to remount part of the file hierarchy somewhere else. The call is: mount --bind olddir newdir" If you do this, then you have your files on tmpfs. Frederick ________________________________________ From: yocto-boun...@yoctoproject.org <yocto-boun...@yoctoproject.org> on behalf of Martin Townsend <mtownsend1...@gmail.com> Sent: Wednesday, May 25, 2016 8:07 AM To: yocto@yoctoproject.org Subject: [yocto] mount bind /var/lib and package management Hi, When using a read only rootfs it mount --binds /var/lib into /var/volatile/lib which lives in tmpfs and makes sense. The problem is that I use dpkg but I'm assuming other package management tools use /var/lib as their admin dir. Wouldn't this break package updates as the dpkg database files etc will then be updated in tmpfs so a power cycle would means the changes are lost? Or am I missing something? I tried to mount bind all directories except dpkg which I managed to get working but other systemd services failed as they expected /var/lib to be writeable (the service that creates /var/lib/machines). I suppose I could alter this to remount / rw first but gave up at this point. The next thing I tried was to use a new admindir for dpkg, ie /lib/dpkg which I have working but I had to hack a lot of files changing /var/lib to /lib including files for apt-get native. I'm not confident that I've got them all. Is there another solution I haven't thought of? Thanks in advance, Martin. -- _______________________________________________ yocto mailing list yocto@yoctoproject.org https://lists.yoctoproject.org/listinfo/yocto -- _______________________________________________ yocto mailing list yocto@yoctoproject.org https://lists.yoctoproject.org/listinfo/yocto