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From c850879b862058a644a05f8fe2fc2206e0e317e8 Mon Sep 17 00:00:00 2001
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From: Harald Hoyer <harald@redhat.com>
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Date: Thu, 3 Sep 2015 16:25:23 +0200
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Subject: [PATCH] dracut.usage.asc: update man page
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- clarify grub2 config for debugging
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- clarify hostonly mode
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---
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dracut.usage.asc | 74 +++++++++++++++---------------------------------
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1 file changed, 23 insertions(+), 51 deletions(-)
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diff --git a/dracut.usage.asc b/dracut.usage.asc
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index 15dc2440..45cbf120 100644
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--- a/dracut.usage.asc
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+++ b/dracut.usage.asc
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@@ -37,10 +37,14 @@ the --hostonly or -H option. Using this option, the resulting image will
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contain only those dracut modules, kernel modules and filesystems, which are
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needed to boot this specific machine. This has the drawback, that you can't put
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the disk on another controller or machine, and that you can't switch to another
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-root filesystem, without recreating the initramfs image. The usage of the
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---hostonly option is only for experts and you will have to keep the broken
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-pieces. At least keep a copy of a general purpose image (and corresponding
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-kernel) as a fallback to rescue your system.
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+root filesystem, without recreating the initramfs image.
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+
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+[NOTE]
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+===============================
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+On RHEL-7 the hostonly mode is the default mode. Generic "non-hostonly" images
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+are created, if the dracut-config-generic rpm is installed. The rescue kernel
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+entry in the bootloader menu is also a generic image.
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+===============================
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=== Inspecting the Contents
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To see the contents of the image created by dracut, you can use the lsinitrd
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@@ -99,8 +103,9 @@ raid with encryption and LVM on top), as long as you specify the correct
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filesystem LABEL or UUID on the kernel command line for your root device, dracut
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will find it and boot from it.
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-The kernel command line usually can be configured in _/boot/grub2/grub.cfg_, if
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-grub is your bootloader and it also can be edited in the real boot process in
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+The kernel command line usually can be configured in _/boot/grub2/grub.cfg_
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+(or _/boot/efi/EFI/redhat/grub.cfg_ for EFI systems), if
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+grub2 is your bootloader and it also can be edited in the real boot process in
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the grub menu.
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The kernel command line can also be provided by the dhcp server with the
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@@ -325,7 +330,8 @@ stick and mount that. Then you can store the output for later inspection.
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In all cases, the following should be mentioned and attached to your bug report:
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* The exact kernel command-line used. Typically from the bootloader
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-configuration file (e.g. _/boot/grub2/grub.cfg_) or from _/proc/cmdline_.
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+configuration file (e.g. _/boot/grub2/grub.cfg_ (or _/boot/efi/EFI/redhat/grub.cfg_ for EFI systems))
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+or from _/proc/cmdline_.
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* A copy of your disk partition information from _/etc/fstab_, which might be
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obtained booting an old working initramfs or a rescue medium.
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* Turn on dracut debugging (see _the 'debugging dracut' section_), and attach
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@@ -359,49 +365,17 @@ Successfully debugging dracut will require some form of console
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logging during the system boot. This section documents configuring a
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serial console connection to record boot messages.
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-. First, enable serial console output for both the kernel and the bootloader.
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-. Open the file _/boot/grub2/grub.cfg_ for editing. Below the line ''timeout=5'', add
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-the following:
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-+
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-----
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-serial --unit=0 --speed=9600
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-terminal --timeout=5 serial console
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-----
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-+
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-. Also in _/boot/grub2/grub.cfg_, add the following boot arguemnts to the ''kernel''
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+. In _/boot/grub2/grub.cfg_ (or _/boot/efi/EFI/redhat/grub.cfg_ for EFI systems),
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+add the following boot arguments to the ''linux16''
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line:
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+
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----
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console=tty0 console=ttyS0,9600
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----
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+
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-. When finished, the _/boot/grub2/grub.cfg_ file should look similar to the example
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-below.
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-+
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-----
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-default=0
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-timeout=5
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-serial --unit=0 --speed=9600
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-terminal --timeout=5 serial console
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-title Fedora (2.6.29.5-191.fc11.x86_64)
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- root (hd0,0)
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- kernel /vmlinuz-2.6.29.5-191.fc11.x86_64 ro root=/dev/mapper/vg_uc1-lv_root console=tty0 console=ttyS0,9600
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- initrd /dracut-2.6.29.5-191.fc11.x86_64.img
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-----
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-+
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. More detailed information on how to configure the kernel for console output
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can be found at
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http://www.faqs.org/docs/Linux-HOWTO/Remote-Serial-Console-HOWTO.html#CONFIGURE-KERNEL.
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-. Redirecting non-interactive output
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-+
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---
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-NOTE: You can redirect all non-interactive output to _/dev/kmsg_ and the kernel
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-will put it out on the console when it reaches the kernel buffer by doing
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-
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-----
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-# exec >/dev/kmsg 2>&1 </dev/console
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-----
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---
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[[using-the-dracut-shell]]
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==== Using the dracut shell
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@@ -410,20 +384,18 @@ dracut offers a shell for interactive debugging in the event dracut fails to
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locate your root filesystem. To enable the shell:
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. Add the boot parameter ''rd.shell'' to your bootloader configuration file
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-(e.g. _/boot/grub2/grub.cfg_)
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+(e.g. _/boot/grub2/grub.cfg_ (or _/boot/efi/EFI/redhat/grub.cfg_ for EFI systems))
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. Remove the boot arguments ''rhgb'' and ''quiet''
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+
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-A sample _/boot/grub2/grub.cfg_ bootloader configuration file is listed below.
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+A sample _grub.cfg_ bootloader configuration file snippet is listed below.
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+
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----
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-default=0
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-timeout=5
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-serial --unit=0 --speed=9600
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-terminal --timeout=5 serial console
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-title Fedora (2.6.29.5-191.fc11.x86_64)
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- root (hd0,0)
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- kernel /vmlinuz-2.6.29.5-191.fc11.x86_64 ro root=/dev/mapper/vg_uc1-lv_root console=tty0 rd.shell
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- initrd /dracut-2.6.29.5-191.fc11.x86_64.img
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+menuentry 'Red Hat Enterprise Linux Server (3.10.0-308.el7.x86_64) 7.0 (Maipo)' […] {
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+ […]
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+ linux16 /vmlinuz-3.10.0-308.el7.x86_64 ro root=/dev/mapper/vg_uc1-lv_root console=tty0 rd.shell
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+ initrd16 /initramfs-3.10.0-308.el7.x86_64.img
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+ […]
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+}
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----
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+
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. If system boot fails, you will be dropped into a shell as seen in the example
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