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137 lines
5.7 KiB
137 lines
5.7 KiB
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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