I tested the initramfs-tools in xenial-proposed, bionic-proposed, and
disco-proposed with all 3 testcases (panic=-1, panic=10, and no panic),
everything worked as expected:
- panic=-1 rebooted instantly after the root partition is not found
- panic=10 rebooted after 10 seconds
- no "panic" entry caused to drop into a basic shell
ii initramfs-tools 0.122ubuntu8.16 all generic modular initramfs generator
(automation)
ii initramfs-tools 0.130ubuntu3.9 all generic modular initramfs generator
(automation)
ii initramfs-tools 0.131ubuntu19.2 all generic modular initramfs generator
(automation)
multipass@xenial:~$ apt-cache policy initramfs-tools
initramfs-tools:
Installed: 0.122ubuntu8.16
Candidate: 0.122ubuntu8.16
Version table:
*** 0.122ubuntu8.16 400
400 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages
100 /var/lib/dpkg/status
0.122ubuntu8.15 500
500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
0.122ubuntu8.14 500
500 http://security.ubuntu.com/ubuntu xenial-security/main amd64
Packages
0.122ubuntu8 500
500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
multipass@bionic:~$ apt-cache policy initramfs-tools
initramfs-tools:
Installed: 0.130ubuntu3.9
Candidate: 0.130ubuntu3.9
Version table:
*** 0.130ubuntu3.9 400
400 http://archive.ubuntu.com/ubuntu bionic-proposed/main amd64 Packages
100 /var/lib/dpkg/status
0.130ubuntu3.8 500
500 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
0.130ubuntu3.6 500
500 http://security.ubuntu.com/ubuntu bionic-security/main amd64
Packages
0.130ubuntu3 500
500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages
multipass@disco:~$ apt-cache policy initramfs-tools
initramfs-tools:
Installed: 0.131ubuntu19.2
Candidate: 0.131ubuntu19.2
Version table:
*** 0.131ubuntu19.2 400
400 http://archive.ubuntu.com/ubuntu disco-proposed/main amd64 Packages
100 /var/lib/dpkg/status
0.131ubuntu19.1 500
500 http://archive.ubuntu.com/ubuntu disco-updates/main amd64 Packages
0.131ubuntu19 500
500 http://archive.ubuntu.com/ubuntu disco/main amd64 Packages
** Tags removed: verification-needed verification-needed-bionic
verification-needed-disco verification-needed-xenial
** Tags added: verification-done-bionic verification-done-disco
verification-done-xenial
--
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to initramfs-tools in Ubuntu.
https://bugs.launchpad.net/bugs/1831252
Title:
panic=-1 is completely ignored by the initrd causing unexpected
behaviour
Status in initramfs-tools package in Ubuntu:
Fix Released
Status in initramfs-tools source package in Xenial:
Fix Committed
Status in initramfs-tools source package in Bionic:
Fix Committed
Status in initramfs-tools source package in Disco:
Fix Committed
Status in initramfs-tools source package in Eoan:
Fix Released
Bug description:
[Impact]
in Ubuntu Core we default to using panic=-1 on the kernel command line
(documented at [1]) to speed up the auto-rollback mechanism of the kernel. on a
kernel level this works just fine and the system reboots immediately ...
when in the initramfs during boot and a panic occurs, no reboot
happens at all, the initrd spawns a shell regardless of the panic=
value ...
[Test case]
Before booting change root=$foo to root=x$foo - this will make it
panic. Then test that
1) "panic=-1" causes an immediate reboot
2) "panic=5" waits 5 seconds
3) no "panic" drops you to a shell
[Regression potential]
This adds some very specific checks for -1 in places that use ${panic}, as
such the regression potential is somewhat limited. If there were a regression,
it could be a syntax error (causing boot to fail) or a sleep not working
correctly (causing sleep to, well, not sleep) - but that's unrealistic.
[Other info]
this is caused by a filter in /usr/share/initramfs-tools/init
panic=*)
panic="${x#panic=}"
case ${panic} in
*[![:digit:].]*)
panic=
;;
esac
;;
this function only lets positive values through, else panic= simply
gets unset
the panic() function itself is also not capable of handling negative
values, it has a sleep call that interprets negative values as
commandline options instead of simply ignoring a negative sleep time
[2] (line 11).
the filter in the init script should allow the -1 value (to comply
with the kernel documentation and behaviour) and the panic() function
should properly skip the sleep call when a negative value for panic=
is set.
[1]
https://github.com/torvalds/linux/blob/v4.17/Documentation/admin-guide/kernel-parameters.txt#L2931
[2] https://paste.ubuntu.com/p/mswD8Cd869/
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/initramfs-tools/+bug/1831252/+subscriptions
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