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Holysword
l33t
Joined: 19 Nov 2006
Posts: 946
Location: Greece
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 Posted: Mon Sep 11, 2017 4:48 pm Post subject: Installing with root directory on an external disk |
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I've been testing some stuff these days and decided to install Gentoo in one of my external hard drivers, while keeping the boot partition at the sda device.
I've tried to add the boot option using efibootmgr (I don't use a bootloader) like this:
| Code: | | efibootmgr -c -d /dev/sda -L "Gentoo Test" -l "\vmlinuz-4.9.48_new" -u "root=/dev/sdc1 rootfstype=ext4 init=/usr/lib/systemd/systemd" |
but I guess that it was a bad idea after all. At boottime I get the error:
| Code: | | kernel panic - not syncing: VFS: /Unable to mount root fs on unknown-block(0,0) |
Is there an (easy) way to do what I'm trying to do?
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Jaglover
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Joined: 29 May 2005
Posts: 8291
Location: Saint Amant, Acadiana
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| Posted: Mon Sep 11, 2017 5:39 pm Post subject: |
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The error is coming from kernel, not bootloader. In other words, check out your kernel configuration and make sure the root device is correct. This /dev/sdc1 seems suspicious to me. What makes you think the kernel you are loading enumerates the external drive as third SCSI block device? I'd use PARTUID instead.
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Holysword
l33t
Joined: 19 Nov 2006
Posts: 946
Location: Greece
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| Posted: Mon Sep 11, 2017 6:45 pm Post subject: |
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| Jaglover wrote: | | The error is coming from kernel, not bootloader. In other words, check out your kernel configuration and make sure the root device is correct. This /dev/sdc1 seems suspicious to me. What makes you think the kernel you are loading enumerates the external drive as third SCSI block device? I'd use PARTUID instead. |
Woops, sorry, old habits die hard. I've tried using PARTUID, but got the same error.
| Code: | sleipnir ~ # efibootmgr -v
BootCurrent: 0000
Timeout: 1 seconds
BootOrder: 000B,0000,0007,0002,0008,0009,000A
Boot0000* Gentoo 4.9.16 HD(1,GPT,b2b17f74-9d02-4dda-9e48-cc931a945e56,0x800,0x40000)/File(\vmlinuz-4.9.16-gentoo)r.o.o.t.=./.d.e.v./.s.d.a.2. .r.o.o.t.f.s.t.y.p.e.=.e.x.t.4. .p.c.i.e._.p.o.r.t._.p.m.=.o.f.f. .r.c.u.t.r.e.e...r.c.u._.i.d.l.e._.g.p._.d.e.l.a.y.=.1. .i.n.i.t.=./.u.s.r./.l.i.b./.s.y.s.t.e.m.d./.s.y.s.t.e.m.d.
Boot000B* Gentoo New HD(1,GPT,b2b17f74-9d02-4dda-9e48-cc931a945e56,0x800,0x40000)/File(\vmlinuz-4.9.48_new)r.o.o.t.=.P.A.R.T.U.U.I.D.=.4.b.1.8.5.f.6.6.-.4.2.8.f.-.4.7.9.1.-.9.b.d.0.-.7.8.a.0.b.6.b.5.f.5.e.7. .r.o.o.t.f.s.t.y.p.e.=.e.x.t.4. .i.n.i.t.=./.u.s.r./.l.i.b./.s.y.s.t.e.m.d./.s.y.s.t.e.m.d.
sleipnir ~ # lsblk -f
NAME FSTYPE LABEL UUID MOUNTPOINT
sda
├─sda1 vfat 4AA0-C2C3 /boot
└─sda2 ext3 f325ddc9-2ef6-4b69-ab40-7eb95f0b1944 /
sdb
└─sdb2 swap swap 205d3dce-02f8-46c9-b374-a4818f141529 [SWAP]
sdc
└─sdc1 ext4 Slave 4b185f66-428f-4791-9bd0-78a0b6b5f5e7 /run/media/holysword/Slave
sleipnir ~ # cat /run/media/holysword/Slave/etc/fstab
/dev/sda1 /boot vfat defaults 0 1
PARTUUID=4b185f66-428f-4791-9bd0-78a0b6b5f5e7 / ext4 noatime 0 1
PARTUUID=205d3dce-02f8-46c9-b374-a4818f141529 none swap sw 0 0
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Are the external drivers supposed to be already readable at this point of the initialization?
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DONAHUE
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Joined: 09 Dec 2006
Posts: 7651
Location: Goose Creek SC
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| Posted: Tue Sep 12, 2017 2:06 am Post subject: |
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In the good old days, placing the / partition on a usb drive generally required using a kernel boot option of either rootwait or rootdelay=<a few seconds> to allow time for the usb drive to "settle". This was even true for flash drives. Probably still true for your situation as the kernel is in charge.
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charles17
Advocate
Joined: 02 Mar 2008
Posts: 3664
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| Posted: Tue Sep 12, 2017 6:32 am Post subject: Re: Installing with root directory on an external disk |
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| Holysword wrote: | | I've been testing some stuff these days and decided to install Gentoo in one of my external hard drivers, while keeping the boot partition at the sda device. |
Why make it so difficult? Consider having an ESP per disk and dropping the kernel there. The computer should recognize all ESPs of all attached disks.
BTW: Some computers provide a built-in alternative to efibootmgr, see https://wiki.gentoo.org/wiki/EFI_System_Partition#UEFI_boot_items
Also, you might want to verify the ESP: | Code: | | blkid | grep b2b17f74-9d02-4dda-9e48-cc931a945e56 |
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54244
Location: 56N 3W
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| Posted: Tue Sep 12, 2017 9:40 am Post subject: |
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Holysword,
Two points. The USB subsystem needs to be started before root is mounted and normally, its not.
That means that
a) the kernel USB support needs to be available.
b) mounting root is delayed until USB is initialised.
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Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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Installing Gentoo
