> On Jul 19, 2024, at 4:45 AM, Gareth de Vaux <[email protected]> wrote: > > Hi all, nextboot warns as follows: > > # nextboot -k testkernel > WARNING: loader(8) has only R/O support for ZFS > nextboot.conf will NOT be reset in case of kernel boot failure > > > This's on a ZFS zroot 12.4-STABLE system.
You're encouraged to upgrade to supported releases ;) > > Does this mean that nextboot will not do its job? I think the WARNING is a good hint and explain why it does not work incase boot failure. The implementation of load desired kernel is write loader parameters to /boot/nexboot.conf , to indicate the loader(8) do its job, that is loading the desired kernel on next boot. Well it is a oneshot boot so the loader will try to disable these parameters by writing `nextboot_enable=NO` to /boot/nexboot.conf. That is the magic. Apparently if loader(8) does not support write to filesystem, in this case the ZFS, it will fail to write /boot/nexboot.conf in case kernel boot failure. Thus subsequent boot the loader(8) would still try to boot from the oneshot `testkernel`. > > I see a blog mentioning that nextboot will write metadata to the ZFS pool > label, > in which case maybe the warning is no longer applicable? That is implementation specific. Normally you can ignore the warning, unless you have trouble booting the kernel. > > > Also I suspect I should rather run "nextboot -D" to revert the situation. > Is this equivalent to removing /boot/nextboot.conf and/or this metadata in the > ZFS pool label? I think normally you do not need that. Best regards, Zhenlei
