grub-btrfs: add custom kernel parameters option for snapshots

Fix #214, #160

Signed-off-by: Pascal Jäger <pascal.jaeger@leimstift.de>

41_snapshots-btrfs

@@ -121,7 +121,7 @@ boot_hs=$(${grub_probe} --device ${boot_device} --target="hints_string" 2>/dev/n
 boot_fs=$(${grub_probe} --device ${boot_device} --target="fs" 2>/dev/null) # Type filesystem of boot device
 
 ## Parameters passed to the kernel
-kernel_parameters="$GRUB_CMDLINE_LINUX $GRUB_CMDLINE_LINUX_DEFAULT"
+kernel_parameters="$GRUB_CMDLINE_LINUX $GRUB_CMDLINE_LINUX_DEFAULT $GRUB_BTRFS_SNAPSHOT_KERNEL_PARAMETERS"
 ## Mount point location
 grub_btrfs_mount_point=$(mktemp -dt grub-btrfs.XXXXXXXXXX)
 ## Class for theme

config

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-GRUB_BTRFS_VERSION=4.12-improve-config-2022-12-05T20:15:10+00:00
+GRUB_BTRFS_VERSION=4.12-improve-config-2022-12-06T21:56:44+00:00
 
 # Disable grub-btrfs.
 # Default: "false"
@@ -48,6 +48,13 @@ GRUB_BTRFS_VERSION=4.12-improve-config-2022-12-05T20:15:10+00:00
 # Default: ("")
 #GRUB_BTRFS_CUSTOM_MICROCODE=("custom-ucode.img" "custom-uc.img "custom_ucode.cpio")
 
+# Additonal kernel command line parameters that should be passed to the kernel
+# when booting a snapshot.
+# For dracut based distros this could be useful to pass "rd.live.overlay.overlayfs=1"
+# or "rd.live.overlay.readonly=1" to the Kernel for booting snapshots read only.
+# Default: ""
+#GRUB_BTRFS_SNAPSHOT_KERNEL_PARAMETERS="rd.live.overlay.overlayfs=1"
+
 # Comma seperated mount options to be used when booting a snapshot.
 # They can be defined here as well as in the "/" line inside the respective snapshots'
 # "/etc/fstab" files.  Mount options found in both places are combined, and this variable

initramfs/readme.md

@@ -39,7 +39,11 @@ You notice that the name of the `hook` must match the name of the 2 installed fi
 Re-generate your initramfs  
 `mkinitcpio -P` (option -P means, all preset present in `/etc/mkinitcpio.d`)
 
+#### Dracut based distros
+Distributions that use Dracut to make their initramfs (many of the Fedora based Distros) simply have to pass either `rd.live.overlay.readonly=1` (to boot into the snapshot read only) or `rd.live.overlay.overlayfs=1` (to act like a livedisk, that is files can be changed but changes will be lost on the next boot) to their kernel command line in grub. 
+Grub-btrfs provides the variable `GRUB_BTRFS_SNAPSHOT_KERNEL_PARAMETERS` to add any command to the kernel command line. Set it to `GRUB_BTRFS_SNAPSHOT_KERNEL_PARAMETERS="rd.live.overlay.overlayfs=1"` to make snapshots immutable when booted into. 
+After changing this run `sudo /etc/grub.d/41_snapshots-btrfs` to generate a new snapshot-submenu with the parameter added. 
+
 #### Other distribution
-Refer to your distribution's documentation  
-or contribute to this project to add a paragraph.
+Refer to your distribution's documentation or contribute to this project to add a paragraph.
 #

manpages/grub-btrfs.8.man

@@ -1,4 +1,4 @@
-.TH "grub-btrfs" "1" 
+.TH "grub-btrfs" "8"
 
 .SH "NAME"
 .PP
@@ -114,6 +114,17 @@ Example: \fCGRUB_BTRFS_NKERNEL=("kernel\-5.19.4\-custom" "vmlinux\-5.19.4\-custo
 \fCGRUB_BTRFS_NINIT=("initramfs\-5.19.4\-custom.img" "initrd\-5.19.4\-custom.img" "otherinit\-5.19.4\-custom.gz")\fP
 \fCGRUB_BTRFS_CUSTOM_MICROCODE=("custom\-ucode.img" "custom\-uc.img "custom_ucode.cpio")\fP
 
+.SS "\fCGRUB_BTRFS_SNAPSHOT_KERNEL_PARAMETERS\fP"
+.PP
+Additonal kernel command line parameters that should be passed to the kernelwhen
+booting a snapshot.
+For dracut based distros this could be useful to pass “rd.live.overlay.overlayfs=1”
+or “rd.live.overlay.readonly=1” to the Kernel for booting read only snapshots.
+.IP \(em 4
+Default: “”
+.IP \(em 4
+Example: \fCGRUB_BTRFS_SNAPSHOT_KERNEL_PARAMETERS="rd.live.overlay.overlayfs=1"\fP
+
 .SS "SNAPSHOT FILTERING"
 .SS "\fCGRUB_BTRFS_IGNORE_SPECIFIC_PATH\fP"
 .PP
@@ -168,7 +179,6 @@ Example: \fCGRUB_BTRFS_BOOT_DIRNAME="/"\fP
 .SS "\fCGRUB_BTRFS_GRUB_DIRNAME\fP"
 .PP
 Location of the folder containing the “grub.cfg” file.
-Used by grub-btrfs to save the file “grub-btrfs.cfg”.
 Might be grub2 on some systems.
 For example, on Fedora with EFI : “/boot/efi/EFI/fedora”
 .IP \(em 4
@@ -183,9 +193,13 @@ Some distributions (like OpenSuSE) store those file at the snapshot directory
 instead of boot. Be aware that this direcory must be available for grub during
 startup of the system.
 .IP \(em 4
-Default: “/boot/grub”
+Default: $GRUB\d\s-2BTRFS\s+2\u\d\s-2GRUB\s+2\u\d\s-2DIRNAME\s+2\u
 .IP \(em 4
+<<<<<<< HEAD
 Example: \fCGRUB_BTRFS_GBTRFS_DIRNAME="/.snapshots"\fP
+=======
+Example \fCGRUB_BTRFS_GBTRFS_DIRNAME="/boot/grub2"\fP
+>>>>>>> e76cdc4 (grub-btrfs: add custom kernel parameters option for snapshots)
 
 .SS "\fCGRUB_BTRFS_GBTRFS_SEARCH_DIRNAME\fP"
 .PP
@@ -204,7 +218,6 @@ with `$\` before the `$`
 .IP \(em 4
 Example: GRUB\d\s-2BTRFS\s+2\u\d\s-2GBTRFS\s+2\u\d\s-2SEARCH\s+2\u\d\s-2DIRNAME\s+2\u=“\${prefix}”
 
-
 .SS "\fCGRUB_BTRFS_MKCONFIG\fP"
 .PP
 Name/path of the command to generate the grub menu, used by “grub-btrfs.service”

manpages/grub-btrfs.8.org

@@ -83,6 +83,14 @@ Customs kernel, initramfs and microcodes that are not detected can be added in t
           ~GRUB_BTRFS_NINIT=("initramfs-5.19.4-custom.img" "initrd-5.19.4-custom.img" "otherinit-5.19.4-custom.gz")~
           ~GRUB_BTRFS_CUSTOM_MICROCODE=("custom-ucode.img" "custom-uc.img "custom_ucode.cpio")~
 
+*** ~GRUB_BTRFS_SNAPSHOT_KERNEL_PARAMETERS~
+Additonal kernel command line parameters that should be passed to the kernelwhen
+booting a snapshot.
+For dracut based distros this could be useful to pass "rd.live.overlay.overlayfs=1"
+or "rd.live.overlay.readonly=1" to the Kernel for booting read only snapshots.
+- Default: ""
+- Example: ~GRUB_BTRFS_SNAPSHOT_KERNEL_PARAMETERS="rd.live.overlay.overlayfs=1"~
+
 ** SNAPSHOT FILTERING
 
 *** ~GRUB_BTRFS_IGNORE_SPECIFIC_PATH~