On 03/06/2018 08:58 PM, Theodore Y. Ts'o wrote: > On Tue, Mar 06, 2018 at 03:34:25PM -0800, Randy Dunlap wrote: >> >> My custom kernel does not use an initramfs at all. > > OK, so if you are not using an initramfs at all, it's *normal* for the > file system to be mounted read-only, since it's not safe to run fsck > on the file system unless it is mounted read-only. So the standard > init scripts (at least in the good old days pre-systemd) expected that > you use the ro option to make sure the root file system is mounted > read-only, and then the init scripts would check the file system if it > was needed, and then the init scripts would remount the file sytsem > read-write afterwards. > > As I mentioned, with many modern distro's this is now done in > initramfs, and with Debian it will actually run the fsck *before* the > root file system is even mounted, and then it can just mount it > read/write. Obviously, if that is what initramfs does, then the init > scripts (or the magic systemd units in the brave new systemd world) > don't need to remount the file system read/write. > > To be honest, there is a huge amount of magic these days in the > initramfs and systemd scripts. I do know that Debian stable supports > using a read-only mount and its systemd setup does the right thing, > because that's how kvm-xfstests works. But with some of the other > distro's (Red Hat Enterprse Linux especially), it's been magic, and > trying to figure out how it works is something I gave up on a long > time ago. I was just amazed that it managed to boot over fiber > channel, and I was glad I never had to debug on the freaking thing > worked. :-/ OK. Thanks, Ted. -- ~Randy
