On Tue, Jan 21, 2014 at 12:10 PM, Hans Beckérus <hans.becke...@gmail.com> wrote: > On Tue, Jan 21, 2014 at 11:23 AM, Anders Darander <and...@chargestorm.se> > wrote: >> * Hans Beckérus <hans.becke...@gmail.com> [140121 11:05]: >>> Things looked ok for a while, /dev was populated properly after boot >>> and all necessary file systems / mount points were created. >>> We were using an ext2 fs in RAM for mounting /. >>> Now, we made a change to instead use a CPIO image compressed using xz >>> and enabled the support in kernel to handle this. >>> This is when our problems started :( Suddenly our system booted with >>> just a very minimalistic /dev folder, containing basically only a few >>> of the devices probed at boot time. >> >>> So, the questions now are: >> >>> - how was /dev populated before when there was no /etc/init.d/mdev? >> >> I haven't checked poky-tiny, or more specifically the kernel >> configurations for it. But based on the description that I cited above, >> I'd guess that poky-tiny has >> CONFIG_DEVTMPFS=y >> CONFIG_DEVTMPFS_MOUNT=y >> enabled. >> > Indeed (from our .config): > > CONFIG_DEVTMPFS=y > CONFIG_DEVTMPFS_MOUNT=y > >> That would mean the the kernel itself were managing /dev for you when >> you were using ext2. Unfortunately, CONFIG_DEVTMPFS_MOUNT do only >> automount devmptfs on /dev if you're not in an initramfs (or initrd). >> > Sounds reasonable. But, when moving from ext2.gz to cpio.xz, we still > did not add any init script for mounting /dev, yet it is still created > and populated? But only with a very limited set of devices. > I guess there is a difference when the kernel mounts the cpio.xz image > compared to expanding the ext2.gz in RAM with respect to how /dev is > handled. But I am only guessing here. > Another thing, You say CONFIG_DEVTMPFS_MOUNT does *not* automount /dev if using the initrd scheme? But I think it did when using the compressed ext2 file system? How come /dev was mounted and populated automatically in the ext2 case but when we changed to cpio.xz things seem to break?
>> Thus, you should add a simple initscript which mounts devtmpfs on /dev. >> Thereafter, you should be fine. >> > Well, using the one that came from busybox-mdev rendered our /dev > completely useless :( > As I said, if I reduce the script to perform only 'mdev -s', then it > works a lot better. So mounting /dev again seems like a bad idea. > >> Regarding your other questions on mdev, it's been a little while since I >> used mdev. Let us know if the ideas above is enough, or if you want to >> dig more into mdev. >> > mdev as a device manager I think we have under control, the confusion > is more in our current system behavior at boot. > >> Cheers, >> Anders >> >> -- >> Anders Darander >> ChargeStorm AB / eStorm AB _______________________________________________ yocto mailing list yocto@yoctoproject.org https://lists.yoctoproject.org/listinfo/yocto
