On Wed, Jun 09, 2021 at 09:02:36AM +0200, Hannes Reinecke wrote: > On 6/9/21 8:38 AM, Christian Brauner wrote: > > On Tue, Jun 08, 2021 at 12:16:43PM -0500, Eric W. Biederman wrote: > > > Hannes Reinecke <hare@xxxxxxx> writes: > > > > > > > On 6/8/21 4:29 PM, Christian Brauner wrote: > > > > > On Tue, Jun 08, 2021 at 04:10:08PM +0200, Hannes Reinecke wrote: > [ .. ] > > > > Granted, modifying sysfs layout is not something for the faint-hearted, > > > > and one really has to look closely to ensure you end up with a > > > > consistent layout afterwards. > > > > > > > > But let's see how things go; might well be that it turns out to be too > > > > complex to consider. Can't tell yet. > > > > > > I would suggest aiming for something like devptsfs without the > > > complication of /dev/ptmx. > > > > > > That is a pseudo filesystem that has a control node and virtual block > > > devices that were created using that control node. > > > > Also see android/binder/binderfs.c > > > Ah. Will have a look. I implemented this a few years back and I think it should've made it onto Android by default now. So that approach does indeed work well, it seems: https://chromium.googlesource.com/aosp/platform/system/core/+/master/rootdir/init.rc#257 This should be easier to follow than the devpts case because you don't need to wade through the {t,p}ty layer. > > > > > > > That is the cleanest solution I know and is not strictly limited to use > > > with containers so it can also gain greater traction. The interaction > > > with devtmpfs should be simply having devtmpfs create a mount point for > > > that filesystem. > > > > > > This could be a new cleaner api for things like loopback devices. > > > > I sent a patchset that implemented this last year. > > > Do you have a pointer/commit hash for this? Yes, sure: https://lore.kernel.org/linux-block/20200424162052.441452-1-christian.brauner@xxxxxxxxxx/ You can also just pull my branch. I think it's still based on v5.7 or sm: https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/log/?h=loopfs I'm happy to collaborate on this too. Christian
