On Monday, 23 September 2019 08:43:52 BST Adam Carter wrote: > On Mon, Sep 23, 2019 at 3:38 PM J. Roeleveld <[email protected]> wrote: > > On 23 September 2019 07:33:44 CEST, Adam Carter <[email protected]> > > > > wrote: > > >Follow on question; what does efibootmgr actually modify? Is it writing > > >to > > >motherboard EEPROM values similar what happens when you write changes > > >in > > >the BIOS setup pages? > > >If you, does mean I may have been able to fix this issue in the BIOS? > > > > It updates something in the CMOS, however, not all UEFI bioses support > > manually editing this. > > I haven't found a decent option for this on any system I own yet, apart > > from efibootmgr. > > Ok thanks. > > Looks like the setting gets cleared with every BIOS update. I assume this > is due to shitty coding by the MB manufacturer and not a limitation of UEFI.
An update of the firmware flashes the UEFI EEPROM and as far as I have experienced no settings are retained. A fresh probe of MoBo devices at first boot re-lists anything bootable. Desktop/workstation UEFI firmware have more features, which allow tweaking boot lists. Some also offer a back up/restore facility for settings from a file. Laptop UEFI boot menus are more sparce, in which case efibootmgr, or with systemd-boot the bootctl command allow managing UEFI boot entries. I believe MSWindows have their own applications to do the same. Regarding the message "GUID partition table header signature is wrong", this is probably indicative of an MBR partition table - but I'm not sure. Have you installed some OS on an MBR partition schema? -- Regards, Mick
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