[systemd-devel] How to debug this strange issue about "systemd"?

[Andrei Borzenkov]

В Wed, 15 Jul 2015 23:03:02 +0800
sean <xrfu at suse.com> пишет:

> Hi All:
> 	I am trying to test the latest upstream kernel, But i encounter a strange issue about systemd.
> When the "systemd" extracted from initrd image mounts the real root file system "hda.img" on "/sysroot" and changes root to the new directory,  it can not found "/sbin/init" and "/bin/sh".
> In fact, These two files exist in the "hda.img".
> How to debug this issue?
> Why does not it enter emergency mode?
> If enter emergency mode, maybe this issue become easy.
> 

You can stop in dracut just before switch root step and examine
environment. At this point root should already be mounted.

> qemu command line:
> qemu-kvm -D /tmp/qemu-kvm-machine.log -m 1024M -append "root=UUID=20059b62-2542-4a85-80cf-41da6e0c1137 rootflags=rw rootfstype=ext4 debug debug_objects console=ttyS0,115200n8 console=tty0
>  rd.debug rd.shell=1 log_buf_len=1M systemd.unit=emergency.target systemd.log_level=debug systemd.log_target=console" -kernel ./qemu_platform/bzImage -hda ./qemu_platform/hda.img 
> -initrd ./qemu_platform/initrd-4.1.0-rc2-7-desktop+ -device e1000,netdev=network0 -netdev user,id=network0 -serial file:/home/sean/work/source/upstream/kernel.org/ttys0.txt
> 
...
> 
> sean at linux-dunz:~/work/source/upstream/kernel.org/qemu_platform> sudo mount -o loop ./hda.img ./hda
> sean at linux-dunz:~/work/source/upstream/kernel.org/qemu_platform> ls -l ./hda/sbin/init
> lrwxrwxrwx 1 sean users 26 Jul 14 22:49 ./hda/sbin/init -> ../usr/lib/systemd/systemd

Do you have separate /usr?

> sean at linux-dunz:~/work/source/upstream/kernel.org/qemu_platform> ls -l ./hda/bin/sh
> lrwxrwxrwx 1 sean users 4 Oct 26  2014 ./hda/bin/sh -> bash
> 
> sean at linux-dunz:~/work/source/upstream/kernel.org/qemu_platform> lsinitrd ./initrd-4.1.0-rc2-7-desktop+ |grep "sbin\/init"
> -rwxr-xr-x   1 root     root         1223 Nov 27  2014 sbin/initqueue
> lrwxrwxrwx   1 root     root           26 Jul 14 21:00 sbin/init -> ../usr/lib/systemd/systemd
> sean at linux-dunz:~/work/source/upstream/kernel.org/qemu_platform> lsinitrd ./initrd-4.1.0-rc2-7-desktop+ |grep "bin\/sh"
> lrwxrwxrwx   1 root     root            4 Jul 14 21:00 bin/sh -> bash
> 
> 
>