On Mon, Nov 19, 2018 at 09:32:52PM +0000, Mathieu Alexandre-Tétreault wrote: > Howdy, > I went through the source code and I have a few questions: > 1. Is efibootguard able to detect a failed boot? How is it handled? From what > I understand, is that the code simply returns using: error_exit.
Hi, yes this is the whole sense of efibootguard. You could read the docs in the docs/ folder. There it is explained. Short version: The whole thing works with using the hardware watchdog timer together with a redundant environment on disk. When you update the system, you trigger a variable in the environment and if the system fails to boot, the watchdog will reset the system and efibootguard will see the already triggered variable and bring the system back to a working state. > 2. I’d like to be able to use a boot counter to toggle the rootfs/kernel > used. > For example, if after three failed boot attempt, the boot switched to > rootfs2 and kernel2. So each time efibootguard boots, the counter is > incremented, and as soon as the kernel is fully loaded a user service > resets the boot counter. As far as I know, this feature is not implemented > in efibootguear (am I wrong?). I was thinking about using the uservars for > that purpose. Is there any concern with that, or things I should be awared > of? You are implementing a completely different logic on top of the actual switching logic then. Also I don't get your example: "... if after three failed boot attempt, the boot switched to rootfs2 and kernel2." Does not make sense to me. efibootguard switches back after the first failed attempt to bring up new rootfs/kernel. It does not test three times but one time. Why would you try it more then once? A system should be reliable. And surely, you can implement your own logic with user variables. You can disable the watchdog and script whatever you want with them. Still I would first suggest you read the docs more thoroughly. Kind regards Andreas > > > > Any advise would be welcomed. > > > > Cheers, > > > > Mathieu > > -- > You received this message because you are subscribed to the Google Groups "EFI > Boot Guard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email > to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web visit https://groups.google.com/d/msgid/ > efibootguard-dev/ > BN6PR1101MB23565CA2C4F289FC0778D387B2D80%40BN6PR1101MB2356.namprd11.prod.outlook.com > . > For more options, visit https://groups.google.com/d/optout. -- Andreas Reichel Dipl.-Phys. (Univ.) Software Consultant [email protected], +49-174-3180074 TNG Technology Consulting GmbH, Betastr. 13a, 85774 Unterfoehring Geschaeftsfuehrer: Henrik Klagges, Dr. Robert Dahlke, Gerhard Mueller Sitz: Unterfoehring * Amtsgericht Muenchen * HRB 135082 -- You received this message because you are subscribed to the Google Groups "EFI Boot Guard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/efibootguard-dev/20181120102049.GA31570%40iiotirae. For more options, visit https://groups.google.com/d/optout.
