hank-test/quick-docs
1
0
Fork 0
mirror of https://pagure.io/fedora-docs/quick-docs.git synced 2024-10-19 01:35:42 +00:00
Code Issues 1 Projects Releases Packages Wiki Activity Actions

Update modules/ROOT/pages/debug-dracut-problems.adoc

Browse source 
Proofread, edited for clarity, populated missing commands and file names, general housekeeping.
This commit is contained in:
Caleb McKee 2020-10-18 07:39:57 +00:00 committed by pbokoc
parent 06d538dbbf
commit 39c95b9414
1 changed files with 67 additions and 100 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

167
modules/ROOT/pages/debug-dracut-problems.adoc
View file

@ -1,37 +1,5 @@
= How to debug Dracut problems
'''
[IMPORTANT]
======
This page was automatically converted from https://fedoraproject.org/wiki/How_to_debug_Dracut_problems
It is probably
* Badly formatted
* Missing graphics and tables that do not convert well from mediawiki
* Out-of-date
* In need of other love
Pull requests accepted at https://pagure.io/fedora-docs/quick-docs
Once you've fixed this page, remove this notice, and update
[filename]`modules/ROOT/nav.adoc`.
Once the document is live, go to the original wiki page and replace its text
with the following macro:
....
{{#fedoradocs: https://docs.fedoraproject.org/whatever-the-of-this-new-page}}
....
======
'''
include::{partialsdir}/unreviewed-message.adoc[]
*Foreword*
If you are experiencing a problem with system initialization due to
@ -46,16 +14,14 @@ well. These should be complete (no snippets please), not in an archive,
uncompressed, with MIME type set as text/plain.
[[identifying-your-problem-area]]
Identifying your problem area
-----------------------------
== Identifying your problem area
1. Remove `rhgb` and `quiet` from the kernel command line
2. Add `rd.shell` to the kernel command line. This will present a shell
should dracut be unable to locate your root device
in case dracut is unable to locate your root device
3. Add `rd.shell rd.debug log_buf_len=1M` to the kernel command line so
that dracut shell commands are printed as they are executed
4. Inspect the system logs:
+
....
# less /run/initramfs/rdsosreport.txt
# journalctl -a
@ -64,50 +30,45 @@ Identifying your problem area
....
[[information-to-include-in-your-report]]
Information to include in your report
-------------------------------------
== Information to include in your report
[[all-bug-reports]]
All bug reports
~~~~~~~~~~~~~~~
=== All bug reports
In all cases, the following should be mentioned and attached to your bug
report:
* The exact kernel command-line used. Typically from the bootloader
configuration file (e.g. ) or from
* A copy of your disk partition information from
configuration file (e.g. `/etc/grub.conf`) or from `/proc/cmdline`
* A copy of your disk partition information from `/etc/fstab`
* A device listing from device-mapper. This can be obtained by running
the command
the command `dmsetup ls -- tree`
* A list of block device attributes including vol_id compatible mode.
This can be obtained by running the commands and
* Turn on dracut debugging (see
link:How_to_debug_Dracut_problems#Debugging[the 'debugging dracut'
This can be obtained by running the commands `blkid` and `blkid -o udev`
* Turn on dracut debugging (see link:How_to_debug_Dracut_problems#Debugging[the 'debugging dracut'
section]), and attach all relevant information from the boot log. This
can be obtained by running the command grep dracut}}.
* If you use a dracut configuration file, please include
can be obtained by running the command `dmesg|grep dracut`
* If you use a dracut configuration file, please include `/etc/dracut.conf`
[[logical-volume-management-related-problems]]
Logical Volume Management related problems
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
=== Logical Volume Management related problems
As well as the information from
link:How_to_debug_Dracut_problems#AllInfo[the 'all bug reports'
section], include the following information:
* Include physical volume information by running the command:
* Include volume group information by running the command:
* Include logical volume information by running the command:
* Include physical volume information by running the command: `lvm pvdisplay`
* Include volume group information by running the command: `lvm vgdisplay`
* Include logical volume information by running the command: `lvm lvdisplay`
[[software-raid-related-problems]]
Software RAID related problems
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
=== Software RAID related problems
As well as the information from
link:How_to_debug_Dracut_problems#AllInfo[the 'all bug reports'
section], include the following information:
* If using software RAID disk partitions, please include the output of
* If using software RAID disk partitions, please include the output of `/proc/mdstat`
[[network-root-device-related-problems]]
Network root device related problems
@ -122,12 +83,10 @@ section], include the following information:
* Please include the output of
[[debugging-dracut]]
Debugging dracut
----------------
== Debugging dracut
[[configure-a-serial-console]]
Configure a serial console
~~~~~~~~~~~~~~~~~~~~~~~~~~
=== Configure a serial console
Successfully debugging dracut will require some form of console logging
during the system boot. This section documents configuring a serial
@ -135,20 +94,21 @@ console connection to record boot messages. To enable serial console
output for both the kernel and the bootloader, follow the procedure
below.
1. Open the file for editing. Below the line _timeout=5_, add the
following:
+
1. Open the file `/etc/grub.conf` for editing. Below the line _timeout=5_, add the following:
....
serial --unit=0 --speed=9600
terminal --timeout=5 serial console
....
2. Also in , add the following boot arguemnts to the _kernel_ line:
+
2. Also in `/etc/grub.conf`, add the following boot arguments to the _kernel_ line:
....
console=tty0 console=ttyS0,9600
....
3. When finished, the file should look similar to the example below.
+
3. When finished, `/etc/grub.conf` should look similar to the example below:
....
default=0
timeout=5
@ -165,17 +125,16 @@ output can be found at
http://www.faqs.org/docs/Linux-HOWTO/Remote-Serial-Console-HOWTO.html#CONFIGURE-KERNEL[1].
[[using-the-dracut-shell]]
Using the dracut shell
~~~~~~~~~~~~~~~~~~~~~~
=== Using the dracut shell
Dracut offers a shell for interactive debugging in the event dracut
fails to locate your root filesystem. To enable the shell:
1. Add the boot parameter `rd.shell` to your bootloader configuration
file (e.g.
file (e.g. `/etc/grub/conf`)
2. Remove the boot arguments `rhgb` and `quiet`
A sample bootloader configuration file is listed below.
A sample `/etc/grub.conf` bootloader configuration file is listed below:
....
default=0
@ -189,7 +148,7 @@ title Fedora (2.6.29.5-191.fc11.x86_64)
....
If system boot fails, you will be dropped into a shell as seen in the
example below.
example below:
....
No root device found
@ -204,28 +163,24 @@ link:How_to_debug_Dracut_problems#AllInfo[the 'all bug reports'
section]).
[[accessing-the-root-volume-from-the-dracut-shell]]
Accessing the root volume from the dracut shell
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
=== Accessing the root volume from the dracut shell
From the dracut debug shell, you can manually perform the task of
locating and preparing your root volume for boot. The required steps
will depend on how your root volume is configured. Common scenarios
include:
* A block device (e.g. )
* A LVM logical volume (e.g. )
* An encrypted device (e.g. )
* A network attached device (e.g.
iscsi:@192.168.0.4::3260::iqn.2009-02.org.fedoraproject:for.all}})
* A block device (e.g. `/dev/sda7`)
* A LVM logical volume (e.g. `/dev/VolGroup00/LogVol00`)
* An encrypted device (e.g. `/dev/mapper/luks-4d5972ea-901c-4584-bd75-1da802417d83`)
* A network attached device (e.g. `netroot=iscsi:@192.168.0.4::3260::iqn.2009-02.org.fedoraproject:for.all`)
The exact method for locating and preparing will vary. However, to
continue with a successful boot, the objective is to locate your root
volume and create a symlink which points to the file system. For
example, the following example demonstrates accessing and booting a root
volume that is an encrypted LVM Logical volume.
volume and create a symlink `/dev/root` which points to the file system. For example, the following example demonstrates accessing and booting a root volume that is an encrypted LVM Logical volume.
1. Inspect your partitions using `parted`:
1. Inspect your partitions using
+
....
# parted /dev/sda -s p
Model: ATA HTS541060G9AT00 (scsi)
@ -237,15 +192,17 @@ Number Start End Size Type File system Flags
1 32.3kB 10.8GB 107MB primary ext4 boot
2 10.8GB 55.6GB 44.7GB logical lvm
....
2. You recall that your root volume was a LVM logical volume. Scan and
activate any logical volumes
+
activate any logical volumes:
....
# lvm vgscan
# lvm vgchange -ay
....
3. You should see any logical volumes now using the command :
+
3. You should see any logical volumes now using the command `blkid`:
....
# blkid
/dev/sda1: UUID="3de247f3-5de4-4a44-afc5-1fe179750cf7" TYPE="ext4"
@ -254,44 +211,54 @@ Number Start End Size Type File system Flags
/dev/mapper/linux-home: UUID="c69127c1-f153-4ea2-b58e-4cbfa9257c5e" TYPE="ext3"
/dev/mapper/linux-swap: UUID="47b4d329-975c-4c08-b218-f9c9bf3635f1" TYPE="swap"
....
4. From the output above, you recall that your root volume exists on an
encrypted block device. Following the guidance disk encryption guidance
from the
http://docs.fedoraproject.org/install-guide/f%7B%7BFedoraVersion%7D%7D/en-US/html/apcs04s04.html[
Installation Guide], you unlock your encrypted root volume.
+
....
UUID=$(cryptsetup luksUUID /dev/mapper/linux-root)
cryptsetup luksOpen /dev/mapper/linux-root luks-$UUID
Enter passphrase for /dev/mapper/linux-root:
Key slot 0 unlocked.
....
5. Next, make a symbolic link to the unlocked root volume
+
....
ln -s /dev/mapper/luks-$UUID /dev/root
....
6. With the root volume available, you may continue booting the system
by exiting the dracut shell
+
....
exit
....
[[summary-of-dracut-kernel-command-line-options]]
Summary of dracut kernel command line options
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
=== Summary of dracut kernel command line options
A selection of the most common debugging related dracut options:
rd.shell : Drop to a shell, if the initramfs fails. +
rd.debug : set -x for the dracut shell. +
rd.break=[cmdline|pre-udev|pre-trigger|initqueue|pre-mount|mount|pre-pivot|cleanup]
: drop the shell on defined breakpoint (use
==== `*rd.shell*`
Drop to a shell, if the initramfs fails.
==== `*rd.debug*`
Set -x for the dracut shell.
==== `*rd.break=[cmdline|pre-udev|pre-trigger|initqueue|pre-mount|mount|pre-pivot|cleanup]*`
Drop the shell on defined breakpoint (use
`egrep 'rd.?break' /usr/lib/dracut/modules.d/99base/init.sh` to find the
breakpoints supported by your dracut version) +
rd.udev.info : set udev to loglevel info +
rd.udev.debug : set udev to loglevel debug::
breakpoints supported by your dracut version)
==== `*rd.udev.info*`
Set udev to loglevel info
==== `*rd.udev.debug*`
Set udev to loglevel debug
See the `dracut.cmdline(7)`
http://man7.org/linux/man-pages/man7/dracut.cmdline.7.html[man page] for