Gentoo Archives: gentoo-user

From: Mick <michaelkintzios@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] Verify uefi installation
Date: Mon, 23 Sep 2019 16:54:50
Message-Id: 6333057.FMx8iXlWP2@dell_xps
In Reply to: Re: [gentoo-user] Verify uefi installation by Adam Carter
1 On Monday, 23 September 2019 08:43:52 BST Adam Carter wrote:
2 > On Mon, Sep 23, 2019 at 3:38 PM J. Roeleveld <joost@××××××××.org> wrote:
3 > > On 23 September 2019 07:33:44 CEST, Adam Carter <adamcarter3@×××××.com>
4 > >
5 > > wrote:
6 > > >Follow on question; what does efibootmgr actually modify? Is it writing
7 > > >to
8 > > >motherboard EEPROM values similar what happens when you write changes
9 > > >in
10 > > >the BIOS setup pages?
11 > > >If you, does mean I may have been able to fix this issue in the BIOS?
12 > >
13 > > It updates something in the CMOS, however, not all UEFI bioses support
14 > > manually editing this.
15 > > I haven't found a decent option for this on any system I own yet, apart
16 > > from efibootmgr.
17 >
18 > Ok thanks.
19 >
20 > Looks like the setting gets cleared with every BIOS update. I assume this
21 > is due to shitty coding by the MB manufacturer and not a limitation of UEFI.
22
23 An update of the firmware flashes the UEFI EEPROM and as far as I have
24 experienced no settings are retained. A fresh probe of MoBo devices at first
25 boot re-lists anything bootable.
26
27 Desktop/workstation UEFI firmware have more features, which allow tweaking
28 boot lists. Some also offer a back up/restore facility for settings from a
29 file.
30
31 Laptop UEFI boot menus are more sparce, in which case efibootmgr, or with
32 systemd-boot the bootctl command allow managing UEFI boot entries. I believe
33 MSWindows have their own applications to do the same.
34
35 Regarding the message "GUID partition table header signature is wrong", this
36 is probably indicative of an MBR partition table - but I'm not sure. Have you
37 installed some OS on an MBR partition schema?
38
39 --
40 Regards,
41 Mick

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Subject Author
Re: [gentoo-user] Verify uefi installation Adam Carter <adamcarter3@×××××.com>