Hi Harald. Thanks a lot for your patience and detailed answer. I'll do my best to help. I will certainly have more questions, especially for the active waiting loop for net as I'm not sure I've understood well. As for systemd I like it very much. My question was about distros that don't like systemd. My wish is to write a dracut module for systemimager and I'd like to avoid managing difference between systemd and non systemd distros. I just hope that dracut systemd module exists on all distros I need to support. Best regards Le 24 févr. 2014 à 09:20, Harald Hoyer <harald@xxxxxxxxxx> a écrit : > On 02/22/2014 09:46 AM, olivier.lahaye1@xxxxxxx wrote: >> Hi Harald, >> >> Thanks you for your detailed response, I'll start to dig my case using your >> tips. I still have few more questions though. >> >>>> 1/ detect all network and all hard drives >> I just want to do the same as a linux installation disk. (as SystemImager is >> a sort of OS install disk). I mean, how do all OS install disk wait that >> needed drivers have finished to initialize? I just need that udev scan >> hardware and load needed drivers, nothing more. isn't there an udev target >> for that? I just need to run my script once network is up and once hard >> drives harve been detected. Can't I set a systemd dependacy on network and >> or disks? does a target matches that kind of need? > > Kind of. In dracut we use udev settle in the dracut initqueue loop to wait > until all needed devices show up. > > Basically, you need to know what to wait for to do the waiting :-) > >> >> - Systemd compatibility with non systemd distros. I see that you answered my >> restion about running my script using systemd, but many distro are not using >> systemd by default. do you think that using dracut with systemd on those >> distros is stable enough for my purpose? (I think about ubuntu, debian, >> rhel6, ...) does it work at least on rhel6? If not, are there alternatives? >> (I need to support: rhel-6+ fedora-17+ debian-6+ ubuntu-1204+ SuSE-11+) > > If you don't want to rely on systemd, you have to use the pure dracut > mechanisms. You create "end of wait" conditions with iniqueue/finished hooks, > where you can also call out to your custom script, and never return, if you want. > >> >> - Kernel boot option. how does the "rd.neednet=1 ip=dhcp" work when used? >> first device found that can get an ip wins? is there an order? if I have 2 >> ethernet devices and I want to create a bond later (thus both connected) is >> eth0 chosen over eth1? (for example if a dhcp servers gives addr to both) >> Isn't there a dracut module for network setup using dhcp and udev (to detect >> hardware) that would add a systemd target? > > As of now, networking is not yet hooked in the systemd mechanism. This will > change in the future, but as of now, these are just custom dracut network > scripts. Setup of the network is driven by the kernel command line or injected > or static pseudo kernel command line options in /etc/cmdline.d/*.conf. > >> >> - Systemd targets required befor I run my script Can I add "After: >> network.target" to make sure I have network initialized? > > Hmm, sadly not yet. > >> >> - Supported filesystems Is there a way to add all supported filesystem to >> the initramfs.img or should I list them all updating the list when new ones >> are added? > > If you generate a non-hostonly aka generic initramfs, all available filesystems > are put in the initramfs. > >> >> - Firmwares for drivers (net) You told me to use "--no-hostonly for network >> + disk", but isn't there an option for include all modules present in >> /lib/modules/<kernel>? At least, does --no-hostonly includes drivers >> firmwares if present when needed? Can rd.neednet=1 ip=dhcp work with a NIC >> that requires a firmware to be loaded? > > yes, firmwares are included for all drivers, which are in the initramfs image. > > To include all /lib/modules/<kernel> you would have to write your own dracut > module, which does exactly that. Needed firmware would be included also > automatically. > >> >> - dractut default modules: how do I know? How do I knwow which modules are >> used by default and which ones are not (thus requiring me to use the -m >> option). For example, I've installed dracut-network which contains many >> modules. is there a sort of depend in it? any doc on that (no man in the >> fedora package and insid the modules. Do I need to reverse engineer the file >> to understand their function and usage?) > > Reverse engineering + the documentation on the kernel command line parameters > is the fastest way to get an overview. Most shell scripts should be fairly easy > to understand. > > All modules have a "check" function in module-setup.sh. If a module is included > is determined at runtime. Recent dracut modules output a warning, why the > module is not included in the initramfs, if a tool is missing. Of course > nothing prevents you from specifying the exact list. > >> >> - dracut redudant options? What is the difference between using >> --filesystems btrfs and --add-drivers btrfs?? What is the difference between >> using --install /usr/sbin/fsck.ext3 and --fscks ext3 > > * --filesystems btrfs > would include the kernel driver btrfs and the fsck tool (if there were any) > * --add-drivers btrfs > would only include the kernel driver > * --fscks ext3 > would only add the fsck.ext3 > * --install <foo> > just installs <foo> without any logic (except shared libs) > >> >> - including modules: are dependancies for modules handled? Does --modules >> includes depending modules. I mean does --module snd includes >> snd_hwdep,snd_timer,snd_hda_codec_idt,snd_pcm,snd_seq,snd_hda_codec,snd_hda_intel,snd_seq_device >> as well? > > "--module" does not exist > > "--modules" is for dracut modules, not kernel modules > > what you probably meant is "--add-drivers snd" > > This would add the kernel driver/module "snd" with all its dependencies > determined with: > > $ modprobe "snd" --ignore-install --show-depends > insmod /lib/modules/3.14.0-0.rc2.git3.2.fc21.x86_64/kernel/sound/soundcore.ko > insmod /lib/modules/3.14.0-0.rc2.git3.2.fc21.x86_64/kernel/sound/core/snd.ko > > So, "snd.ko soundcore.ko" ... nothing of snd_hda_intel. > > >> >> Sorry to bother whith such questions, but I'm completely new in this early >> OS boot world. As I said before, google is of no help for me as 99.99% of >> answers are about creating a simple initrd for OS boot. So if you could >> bootstrap my knowledge, that would greatly help me in fixing SystemImager >> faster. >> >> Best regards, >> >> Olivier. > > No problem. What you can do right now is: > * ask me more questions > * clarify the documentation in the dracut project (asciidoc *.asc files) > * send patches for the documentation > -> win-win for all of us -- To unsubscribe from this list: send the line "unsubscribe initramfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
