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author | Kay Sievers <kay@vrfy.org> | 2012-06-28 20:10:31 +0200 |
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committer | Kay Sievers <kay@vrfy.org> | 2012-06-28 20:10:31 +0200 |
commit | a9f0f13910eddddcc4d48cb6ea44f85bd249a67c (patch) | |
tree | ae6b2419460378d760aedc0add753c6f26eb410a /README |
initial import1
Diffstat (limited to 'README')
-rw-r--r-- | README | 93 |
1 files changed, 93 insertions, 0 deletions
@@ -0,0 +1,93 @@ +Simple UEFI boot loader which executes configured EFI images, where the +default entry is selected by a configured pattern (glob) or an on-screen +menu. + +Operates on the EFI System Partition (ESP) only. Configuration file fragments, +kernels, initrds, other EFI images need to reside on the EFS. Linux kernels +need to be built with CONFIG_EFI_STUB to be able to be directly executed as +an EFI image. + +Reads simple and entirely generic boot loader configurion files; one +file per boot loader entry to select from. + +Pressing the space (or most other) keys during bootup will show +an on-screen menu with all configured loader entries to select from. +Pressing enter on the selected entry loads and starts the EFI image. + +If no timeout is configured and no key pressed during bootup, the default +entry is booted right away. + +The config files should be named like: + (ESP)/loader/entries/<vendor>-<release>.conf + + $ cat /boot/loader/entries/fedora-3.5.4-1.fc18.x86_64.conf + title Fedora 18 (3.5.4-1.fc17.x86_64) + linux /fedora/vmlinuz-3.5.4-1.fc17.x86_64 + initrd /fedora/initrd-3.5.4-1.fc17.x86_64 + options root=UUID=f8f83f73-df71-445c-87f7-31f70263b83b + + $ cat /boot/loader/entries/custom-kernel.conf + title My test Kernel - without initramfs + options root=PARTUUID=084917b7-8be2-4e86-838d-f771a9902e08 + linux /bzImage + + $ cat /boot/loader/entries/redhat-grub.conf + title GRUB + efi /EFI/redhat/grub2-efi/grub.efi + + $ cat /boot/loader/entries/zzz-efi-shell.conf + title EFI Shell + efi /EFI/shell/Shell.efi + +Paths are automatically converted from '/' to '\', and a leading '\' is +added if needed. + +Loader options can be stored in: + (ESP)/loader/loader.conf + + $ cat /boot/loader/loader.conf + timeout 10 + default fedora-* + +The timeout is specified in seconds, the default is 0, which suppresses the +menu. If a timeout is given, in the config file or in the EFI variable +"LoaderConfigTimeout", the on-screen menu with the default entry selected is +shown, and a timer counting downwards. + +Pressing the '+' or '-' key in the menu will set or clear a custom timeout +value. The setting is stored persistently in the EFI variable "LoaderConfigTimeout". + +The default entry is selected by a pattern match on the configuration file +names. The matched strings are basenames of the config files translated to +lowercase and without the ".conf" suffix. The last matching entry in the +sorted list is selected. If no match pattern is specified, the last entry in +the list is selected. + +This will automatically select the latest Fedora kernel entry: + default fedora-* + +This will automatically select the latest Fedora 18 kernel: + default fedora-*.fc18.* + +Pressing the 'd' key in the menu will mark the selected entry as the default +boot entry. The entry is identified by a leading '*'. Pressing the 'd' key again +will clear the setting. The setting is stored persistently in the EFI variable +"LoaderConfigDefault". + +Pressing 'o' allows to edit the options for this bootup. + +Pressing 'v' shows the loader and EFI version numbers. + +Pressing 'F1' will show the available keys. + +The EFI variable LoaderEntryOneShot= can be used to specify a loader entry +for the next and only the next reboot. The variable will always be cleared +directly after it is read. + +Before executing the selected image, the boot entry indentifier is stored in +the EFI variable "LoaderEntrySelected" and available during runtime at: + /sys/firmware/efi/vars/LoaderEntrySelected-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f/ + +The allocated random UUID 4a67b082-0a4c-41cf-b6c7-440b29bb8c4f is meant to be +shared across tools which implement the config file layout, format, and the EFI +variables. |