Messages in this thread | | | Date | Fri, 31 Jan 2020 07:43:27 +0100 | From | Ingo Molnar <> | Subject | Re: 5.6-### doesn't boot |
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Thu, Jan 30, 2020 at 9:32 AM Jörg Otte <jrg.otte@gmail.com> wrote: > > > > my notebook doesn't boot with current kernel. Booting stops right after > > displaying "loading initial ramdisk..". No further displays. > > Also nothing is wriiten to the logs. > > > > last known good kernel is : vmlinuz-5.5.0-00849-gb0be0eff1a5a > > first known bad kernel is : vmlinuz-5.5.0-01154-gc677124e631d > > It would be lovely if you can bisect a bit. But my merges in that > range are all from Ingo: > > Ingo Molnar (7): > header cleanup > objtool updates > RCU updates > EFI updates > locking updates > perf updates > scheduler updates
If I had to guess then perhaps the EFI changes look the most dangerous ones from these trees - but in principle most of these trees could contain a boot crasher/hang bug.
> but not having any messages at all makes it hard to guess where it > would be.
To improve debug output:
Removing any 'fbcon' options in /boot/grub/grub.cfg and adding this to the boot options might improve the debug output:
earlyprintk=vga initcall_debug ignore_loglevel debug panic_on_warn
So for example if the relevant kernel boot entry in grub.cfg looks like this:
linux /vmlinuz-5.3.0-26-generic root=UUID=1bcxabe3-0b62-4x04-b456-47cd90c0e6x4 ro splash $vt_handoff
Then editing it to the following could in principle produce (much) more verbose boot output:
linux /vmlinuz-5.3.0-26-generic root=UUID=1bcxabe3-0b62-4x04-b456-47cd90c0e6x4 ro earlyprintk=vga initcall_debug ignore_loglevel debug panic_on_warn $vt_handoff
If this produces more output than just "loading initial ramdisk..' then a photo of the hung screen would be sufficient, no need to transcribe it.
> A few bisect runs would narrow it down a fair amount. Bisecting all the > way would be even better, of course,
Agreed!
If compiling full kernels for bisections takes too long (for example because the .config is from a distro kernel) then running "make localmodconfig" to create a config tailored to the currently active modules will cut down significantly on build time.
Also, a warning: if the normal boot log contains spurious warnings then the new 'panic_on_warn' option will cause additional trouble on good kernels.
Thanks,
Ingo
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