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| -rw-r--r-- | doc/guix.texi | 66 |
1 files changed, 58 insertions, 8 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index 82241b010a..538e7cceab 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -28682,7 +28682,15 @@ The type of a bootloader configuration declaration. @cindex BIOS, bootloader The bootloader to use, as a @code{bootloader} object. For now @code{grub-bootloader}, @code{grub-efi-bootloader}, -@code{extlinux-bootloader} and @code{u-boot-bootloader} are supported. +@code{grub-efi-netboot-bootloader}, @code{extlinux-bootloader} and +@code{u-boot-bootloader} are supported. + +@cindex ARM, bootloaders +@cindex AArch64, bootloaders +Available bootloaders are described in @code{(gnu bootloader @dots{})} +modules. In particular, @code{(gnu bootloader u-boot)} contains definitions +of bootloaders for a wide range of ARM and AArch64 systems, using the +@uref{https://www.denx.de/wiki/U-Boot/, U-Boot bootloader}. @vindex grub-efi-bootloader @code{grub-efi-bootloader} allows to boot on modern systems using the @@ -28694,12 +28702,52 @@ when you boot it on your system. @code{grub-bootloader} allows you to boot in particular Intel-based machines in ``legacy'' BIOS mode. -@cindex ARM, bootloaders -@cindex AArch64, bootloaders -Available bootloaders are described in @code{(gnu bootloader @dots{})} -modules. In particular, @code{(gnu bootloader u-boot)} contains definitions -of bootloaders for a wide range of ARM and AArch64 systems, using the -@uref{https://www.denx.de/wiki/U-Boot/, U-Boot bootloader}. +@vindex grub-efi-netboot-bootloader +@code{grub-efi-netboot-bootloader} allows you to boot your system over network +through TFTP. In combination with an NFS root file system this allows you to +build a diskless Guix system. + +The installation of the @code{grub-efi-netboot-bootloader} generates the content +of the TFTP root directory at @code{target} +(@pxref{Bootloader Configuration, @code{target}}), to be served by a TFTP server. + You may want to mount your TFTP server directory onto @code{target} to move the +required files to the TFTP server automatically. + +If you plan to use an NFS root file system as well (actually if you mount the +store from an NFS share), then the TFTP server needs to serve the file +@file{/boot/grub/grub.cfg} and other files from the store (like GRUBs background +image, the kernel (@pxref{operating-system Reference, @code{kernel}}) and the +initrd (@pxref{operating-system Reference, @code{initrd}})), too. All these +files from the store will be accessed by GRUB through TFTP with their normal +store path, for example as +@file{tftp://tftp-server/gnu/store/…-initrd/initrd.cpio.gz}. + +Two symlinks are created to make this possible. The first symlink is +@code{target}@file{/efi/Guix/boot/grub/grub.cfg} pointing to +@file{../../../boot/grub/grub.cfg}, +where @code{target} may be @file{/boot}. In this case the link is not leaving +the served TFTP root directory, but otherwise it does. The second link is +@code{target}@file{/gnu/store} and points to @file{../gnu/store}. This link +is leaving the served TFTP root directory. + +The assumption behind all this is that you have an NFS server exporting the root +file system for your Guix system, and additionally a TFTP server exporting your +@code{target} directory—usually @file{/boot}—from that same root file system for +your Guix system. In this constellation the symlinks will work. + +For other constellations you will have to program your own bootloader installer, +which then takes care to make necessary files from the store accessible through +TFTP, for example by copying them into the TFTP root directory at @code{target}. + +It is important to note that symlinks pointing outside the TFTP root directory +may need to be allowed in the configuration of your TFTP server. Further the +store link exposes the whole store through TFTP. Both points need to be +considered carefully for security aspects. + +Beside the @code{grub-efi-netboot-bootloader}, the already mentioned TFTP and +NFS servers, you also need a properly configured DHCP server to make the booting +over netboot possible. For all this we can currently only recommend you to look +for instructions about @acronym{PXE, Preboot eXecution Environment}. @item @code{target} This is a string denoting the target onto which to install the @@ -28710,7 +28758,9 @@ The interpretation depends on the bootloader in question. For the bootloader @command{installer} command, such as @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub, GNU GRUB Manual}). For @code{grub-efi-bootloader}, it should be the mount point of the EFI file -system, usually @file{/boot/efi}. +system, usually @file{/boot/efi}. For @code{grub-efi-netboot-bootloader}, +@code{target} should be the mount point corresponding to the TFTP root +directory of your TFTP server. @item @code{menu-entries} (default: @code{()}) A possibly empty list of @code{menu-entry} objects (see below), denoting |