Hi Anto, I just committed preliminary support for using vdevd with devtmpfs. vdevd should automatically detect whether or not devtmpfs is mounted on /dev, and nevertheless run device setup scripts (by using its own device metadata tree in /dev/vdev/ to see whether or not the device was actually processed).
NB for developers: this problem isn't specific to Linux--I expect to encounter it with FreeBSD as well, since it has a full-blown in-kernel devfs. vdevd will keep track of "OS quirks" in the future--one of which is the "Device Already Exists" quirk, whereby vdevd simply expects the OS to provide the device file (regardless of the mechanism). The Linux-specific vdevd back-end now checks to see if vdevd will create files on a devtmpfs filesystem, and enables that quirk if so. Funny, undocumented (!!) discovery: the devtmpfs filesystem type (see statfs(2)) is the same (!!) as the tmpfs filesystem type, despite being a fundamentally different filesystem. I'm surprised that this wasn't caught during the devtmpfs code review--guess I'll have to file a bug report. Anyway, if you find yourself wondering why vdev has to detect devtmpfs by parsing /proc/mounts and verifying that the realpath of the mountpoint is the same as or is a subdirectory of a devtmpfs mountpoint, that's why--we (currently) can't rely on the f_fsid in statfs(2) or statvfs(2). Thanks, Jude On Thu, Apr 16, 2015 at 8:28 PM, Jude Nelson <jud...@gmail.com> wrote: > Hi Anto, > > [snip] > >> I am not really sure if I understood what you explained. I don't think I >> have devtmpfs on my PC when I use the working initrd. The one mounted on >> /dev with the type of devtmpfs is udev. Here are the output of mount and >> the content of my fstab. >> >> root@hp8530w:~# uname -a >> Linux hp8530w 3.18.11-1v1-hp8530w #1 SMP Wed Apr 15 00:49:22 CEST 2015 >> x86_64 GNU/Linux >> root@hp8530w:~# >> root@hp8530w:~# mount >> sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime) >> proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) >> udev on /dev type devtmpfs (rw,relatime,size=10240k,nr_ >> inodes=492536,mode=755) >> devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime, >> gid=5,mode=620,ptmxmode=000) >> tmpfs on /run type tmpfs (rw,nosuid,noexec,relatime, >> size=401084k,mode=755) >> /dev/disk/by-uuid/c0e1e620-5636-48f2-90dd-4d246d58b815 on / type ext4 >> (rw,relatime,errors=remount-ro,data=ordered) >> tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec, >> relatime,size=5120k) >> tmpfs on /run/shm type tmpfs (rw,nosuid,nodev,noexec, >> relatime,size=1641020k) >> fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime) >> /dev/sda2 on /home type ext4 (rw,relatime,data=ordered) >> root@hp8530w:~# >> > > You have devtmpfs mounted. It's this line here: > > > udev on /dev type devtmpfs (rw,relatime,size=10240k,nr_ > inodes=492536,mode=755) > > If you run "mount" while in the initramfs, you might see devtmpfs as > well. If so, then please make sure that you're using vdev's initramfs > "init" script in example/initramfs/init, instead of the one in > /usr/share/initramfs-tools/init. Vdev's init does not mount devtmpfs, but > initramfs-tool's init does. Devtmpfs cannot be mounted on /dev while vdev > is running (but I'll fix this soon). > > >> root@hp8530w:~# cat /etc/fstab >> # /etc/fstab: static file system information. >> # >> # Use 'blkid' to print the universally unique identifier for a >> # device; this may be used with UUID= as a more robust way to name devices >> # that works even if disks are added and removed. See fstab(5). >> # >> # <file system> <mount point> <type> <options> <dump> <pass> >> # / was on /dev/sda1 during installation >> UUID=c0e1e620-5636-48f2-90dd-4d246d58b815 / ext4 >> errors=remount-ro 0 1 >> # /home was on /dev/sda2 during installation >> UUID=5be7af77-0d10-4685-989f-1004b1eabec8 /home ext4 defaults >> 0 2 >> # swap was on /dev/sda3 during installation >> UUID=3a37a27d-84cc-4d06-9920-5419bb4ccbae none swap sw >> 0 0 >> # /dev/sr0 /media/cdrom0 udf,iso9660 user,noauto 0 0 >> /dev/cdrom1 /media/cdrom0 udf,iso9660 user,noauto 0 0 >> # /dev/cdrom /media/cdrom0 udf,iso9660 user,noauto 0 0 >> root@hp8530w:~# > > > This is more evidence to me that the reason you got dropped into a shell > in the initramfs was because vdev saw the /dev/sd* device files from > devtmpfs, and (incorrectly) thought that they had already been processed > and thus didn't go on to generate > /dev/disk/by-uuid/c0e1e620-5636-48f2-90dd-4d246d58b815, > /dev/disk/by-uuid/5be7af77-0d10-4685-989f-1004b1eabec8, and > /dev/disk/by-uuid/3a37a27d-84cc-4d06-9920-5419bb4ccbae. Again, the fix > for now is to ensure that devtmpfs isn't mounted :) > > >> >> >> For those who don't know, devtmpfs is basically a no-frills devfs that >>> modern udev now requires to be mounted to work correctly (i.e. devtmpfs >>> makes the device files these days, not udev). vdevd is currently not >>> compatible with devtmpfs, since it expects to create all the device files >>> itself. I'll update the Linux port to check of devtmpfs is mounted before >>> running, so vdevd will still run the helper scripts even if devtmpfs >>> created the device files already. >>> >>> I am not sure if this would be relevant. I am using file-rc >>> instead of sysv-rc, so I didn't actually have any /etc/rc?.d >>> directories. After the installation of the "example", /etc/rcS.d >>> directory and S02vdev link under it got created. It could possibly >>> be a problem later on, but I think I will worry about that (add it >>> into /etc/runlevel.conf) after the boot process can reach it. >>> >>> >>> That is relevant! I had assumed in the Makefile that the user is using >>> sysv-rc, with the /etc/rc*.d/ directories. >>> >>> I'm not familiar with using file-rc, but I don't think it's involved in >>> the initramfs boot process (at least, not directly). That's all controlled >>> by the files in /usr/share/initramfs-tools/. However, I'd be happy to >>> patch the Makefile in example/ to install the vdev init script correctly >>> for file-rc users :) I just need to know what to do--could you maybe send >>> me a small script that would achieve this? >>> >>> Thanks again, >>> Jude >>> >>> >> A small script? I am just a user so I didn't create any scripts for >> file-rc. :) Perhaps you can find the scripts that you are after on >> http://ftp.debian.org/debian/pool/main/f/file-rc/file-rc_0.8.15_all.deb, >> as that is the one I use and I don't modify anything. >> >> root@hp8530w:~# apt-cache policy file-rc >> file-rc: >> Installed: 0.8.15 >> Candidate: 0.8.15 >> Version table: >> *** 0.8.15 0 >> 870 http://ftp.debian.org/debian/ wheezy/main amd64 Packages >> 100 /var/lib/dpkg/status >> root@hp8530w:~# >> >> Let's just worry about file-rc and sysv-rc later on after we can pass >> initramfs. How about that? >> > > Sounds good :) I'll take a look at file-rc. > > >> >> I have a plan this week end to dust off my Mini-ITX PC to be used for >> properly testing your vdev (or any Devuan packages), instead of using my >> notebook. So I can use sysv-rc and any packages that will make you easier >> to develop your vdev. I will post that on different topic later on. >> > > I look forward to it! Thanks again for your help! > > -Jude >
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