Gentoo Archives: gentoo-user

From: Grant Edwards <grant.b.edwards@×××××.com>
To: gentoo-user@l.g.o
Subject: [gentoo-user] Re: Exact setting in grub to default to a kernel by name?
Date: Mon, 14 Jun 2021 01:00:53
Message-Id: sa69nm$sip$1@ciao.gmane.io
In Reply to: Re: [gentoo-user] Re: Exact setting in grub to default to a kernel by name? by Walter Dnes
1 On 2021-06-13, Walter Dnes <waltdnes@××××××××.org> wrote:
2 > On Sun, Jun 13, 2021 at 05:38:53PM -0000, Grant Edwards wrote
3 >> On 2021-06-13, Walter Dnes <waltdnes@××××××××.org> wrote:
4 >>
5 >> > I'd be tempted to do a manual gub.cfg if I had documentation.
6 >>
7 >> I gave up on the grub2 auto-magical config system many years ago. My
8 >> grub.cfg is typically 10-20 lines long. The documentation is at
9 >>
10 >> https://www.gnu.org/software/grub/manual/grub/grub.html
11 >>
12 >> For manual confiuration: see section 6:
13 >>
14 >> https://www.gnu.org/software/grub/manual/grub/html_node/Configuration.html#Configuration
15 >
16 > When experimenting with this, I'll backup grub.cfg. If things go
17 > awry, boot with the USB key I used for the install, and copy back the
18 > old known working grub.cfg. I've done a first crack at this. I assume
19 > that nothing in /etc/default/grub will have any effect. Questions...
20 >
21 > 1) Is "insmod extfs3" necessary? I've built extfs3 into the kernels.
22
23 I've never used it it, and my boot partitions are always ext3/4
24
25 > 2) I assume that the the first "menuentry" will be the default boot?
26
27 Unless you set the `default` variable to something other than 0
28
29 > 3) Is the default timeout still 5 seconds?
30
31 Dunny, I always set 'timeout=10'
32
33 > 3) I assume that 640x480 is supported on just about every monitor
34 > out there. I want as large text as possible. My eyes are
35 > getting old... just like me. Any obvious errors in the following
36 > grub.cfg?
37
38
39
40 >
41 >=====================================================================
42 > menuentry 'Linux Experimental' --class gnu-linux {
43 > set gfxpayload=640x480
44 > insmod ext3fs
45 > set root='hd0,gpt1'
46 > linux /vmlinuz-experimental root=/dev/sda2 ro noexec=on net.ifnames=0 intel_pstate=disable ipv6.disable=1
47 > }
48
49 I don't know if you really need the gfxpayload or the insmod lines, I don't
50 recall ever needing those to boot kernels from ext3/4 partitions.
51
52 All my grub.cfg files looks like this:
53
54 ========================================================================
55 timeout=10
56 root=hd0,1
57 default=0
58
59 menuentry 'vmlinuz-5.10.27-gentoo' {
60 linux /boot/vmlinuz-5.10.27-gentoo root=/dev/sda1
61 }
62
63 menuentry 'vmlinuz-5.4.97-gentoo' {
64 linux /boot/vmlinuz-5.4.97-gentoo root=/dev/sda1
65 }
66 ========================================================================
67
68 > Something that occured to me. Can I move the duplicated lines to the
69 > top of the file and take them out of the menuentries? E.g.
70
71 Yes.

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Subject Author
Re: [gentoo-user] Re: Exact setting in grub to default to a kernel by name? Walter Dnes <waltdnes@××××××××.org>