diff options
Diffstat (limited to 'docs/gnulinux/grub_cbfs.md')
| -rw-r--r-- | docs/gnulinux/grub_cbfs.md | 103 |
1 files changed, 49 insertions, 54 deletions
diff --git a/docs/gnulinux/grub_cbfs.md b/docs/gnulinux/grub_cbfs.md index 4b58d3e5..d1c5428a 100644 --- a/docs/gnulinux/grub_cbfs.md +++ b/docs/gnulinux/grub_cbfs.md @@ -1,5 +1,6 @@ --- title: How to replace the default GRUB configuration file +x-toc-enable: true ... Libreboot on x86 uses the GRUB @@ -24,29 +25,15 @@ the libreboot GRUB payload will automatically search for. Here is an excellent writeup about CBFS (coreboot filesystem): <http://lennartb.home.xs4all.nl/coreboot/col5.html>. -**This guide is \*only\* for the GRUB payload. If you use the -depthcharge payload, ignore this section entirely.** - -Table of Contents -================= - -- [Introduction](#introduction) -- [1st option: don't re-flash](#option1_dont_reflash) -- [2nd option: re-flash](#option2_reflash) - - [Acquire the necessary utilities](#tools) - - [Acquiring the correct ROM image](#rom) - - [Extract grubtest from the ROM image](#extract_testconfig) - - [Re-insert the modified grubtest.cfg into the ROM - image](#reinsert_modified_testconfig) - - [Testing](#testing) - - [Final steps](#final_steps) +*This guide is only for the GRUB payload. If you use the depthcharge payload, +ignore this section entirely.* Introduction ------------ Download the latest release from [libreboot.org](/)\ -**If you downloaded from git, refer to -[../git/\#build\_meta](../git/#build_meta) before continuing.** +*If you downloaded from git, refer to +[../git/\#build\_meta](../git/#build_meta) before continuing.* There are several advantages to modifying the GRUB configuration stored in CBFS, but this also means that you have to flash a new libreboot ROM @@ -58,7 +45,7 @@ If you aren't up to that then don't worry; it is possible to use a custom GRUB menu without flashing a new image, by loading a GRUB configuration from a partition on the main storage instead. -1st option: don't re-flash {#option1_dont_reflash} +1st option: don't re-flash --------------------------- By default, GRUB in libreboot is configured to scan all partitions on @@ -67,10 +54,10 @@ the main storage for /boot/grub/libreboot\_grub.cfg or partition), and then use it automatically. Simply create your custom GRUB configuration and save it to -**/boot/grub/libreboot\_grub.cfg** on the running system. The next time +`/boot/grub/libreboot_grub.cfg` on the running system. The next time you boot, GRUB (in libreboot) will automatically switch to this -configuration file. **This means that you do not have to re-flash, -recompile or otherwise modify libreboot at all!** +configuration file. *This means that you do not have to re-flash, +recompile or otherwise modify libreboot at all!* Ideally, your distribution should automatically generate a libreboot\_grub.cfg file that is written specifically under the @@ -86,30 +73,31 @@ If you want to adapt a copy of the existing *libreboot* GRUB configuration and use that for the libreboot\_grub.cfg file, then follow [\#tools](#tools), [\#rom](#rom) and [\#extract\_testconfig](#extract_testconfig) to get the -***grubtest.cfg***. Rename ***grubtest.cfg*** to -***libreboot\_grub.cfg*** and save it to ***/boot/grub/*** on the +`grubtest.cfg`. Rename `grubtest.cfg` to +`libreboot_grub.cfg` and save it to `/boot/grub/` on the running system where it is intended to be used. Modify the file at that location however you see fit, and then stop reading this guide (the rest -of this page is irrelevant to you); **in libreboot\_grub.cfg on disk, if +of this page is irrelevant to you); in `libreboot_grub.cfg` on disk, if you are adapting it based on grub.cfg from CBFS then remove the check -for libreboot\_grub.cfg otherwise it will loop.**. +for `libreboot_grub.cfg` otherwise it will loop. -2nd option: re-flash {#option2_reflash} +2nd option: re-flash -------------------- You can modify what is stored inside the flash chip quite easily. Read on to find out how. -Acquire the necessary utilities {#tools} +Acquire the necessary utilities ------------------------------- -Use ***cbfstool*** and ***flashrom***. There are available in the +Use `cbfstool` and `flashrom`. There are available in the *libreboot\_util* release archive, or they can be compiled (see [../git/\#build\_flashrom](../git/#build_flashrom)). Flashrom is also available from the repositories: + # pacman -S flashrom -Acquiring the correct ROM image {#rom} +Acquiring the correct ROM image ------------------------------- You can either work directly with one of the ROM images already included @@ -119,20 +107,22 @@ image file is named *libreboot.rom*, so please make sure to adapt. ROM images are included pre-compiled in libreboot. You can also dump your current firmware, using flashrom: + $ sudo flashrom -p internal -r libreboot.rom # flashrom -p internal -r libreboot.rom -If you are told to specify the chip, add the option **-c {your chip}** -to the command, for example: + +If you are told to specify the chip, add the option `-c {your chip}` to the +command, for example: # flashrom -c MX25L6405 -p internal -r libreboot.rom -Extract grubtest.cfg from the ROM image {#extract_testconfig} +Extract grubtest.cfg from the ROM image --------------------------------------- You can check the contents of the ROM image, inside CBFS: - $ cd \.../libreboot\_util/cbfstool** $ ./cbfstool libreboot.rom -print** + $ cd .../libreboot\_util/cbfstool + $ ./cbfstool libreboot.rom The files *grub.cfg* and *grubtest.cfg* should be present. grub.cfg is loaded by default, with a menuentry for switching to grubtest.cfg. In @@ -145,7 +135,7 @@ Extract grubtest.cfg from the ROM image: Modify the grubtest.cfg accordingly. -Re-insert the modified grubtest.cfg into the ROM image {#reinsert_modified_testconfig} +Re-insert the modified grubtest.cfg into the ROM image ------------------------------------------------------ Once your grubtest.cfg is modified and saved, delete the unmodified @@ -153,34 +143,39 @@ config from the ROM image: $ ./cbfstool libreboot.rom remove -n grubtest.cfg -Next, insert the modified version:\ -**\$ ./cbfstool libreboot.rom add -n grubtest.cfg -f grubtest.cfg -t -raw** +Next, insert the modified version: + + $ ./cbfstool libreboot.rom add -n grubtest.cfg -f grubtest.cfg -t raw Testing ------- -**Now you have a modified ROM. Refer back to +Now you have a modified ROM. Refer back to [../install/\#flashrom](../install/#flashrom) for information on how to flash it. - $ cd /libreboot\_util** \# **./flash update libreboot.rom\ + + $ cd /libreboot\_util + # ./flash update libreboot.rom + Ocassionally, coreboot changes the name of a given board. If flashrom complains about a board mismatch, but you are sure that you chose the correct ROM image, then run this alternative command: + # ./flash forceupdate libreboot.rom -You should see **"Verifying flash\... VERIFIED."** written at the end + +You should see `Verifying flash... VERIFIED.` written at the end of the flashrom output. Once you have done that, shut down and then boot -up with your new test configuration.** +up with your new test configuration. Choose (in GRUB) the menu entry that switches to grubtest.cfg. If it works, then your config is safe and you can continue below. -**If it does not work like you want it to, if you are unsure or +*If it does not work like you want it to, if you are unsure or sceptical in any way, then re-do the steps above until you get it right! -Do \*not\* proceed past this point unless you are 100% sure that your -new configuration is safe (or desirable) to use.** +Do not proceed past this point unless you are 100% sure that your +new configuration is safe (or desirable) to use.* -Final steps {#final_steps} +Final steps ----------- When you are satisfied booting from grubtest.cfg, you can create a copy @@ -190,10 +185,12 @@ difference: the menuentry 'Switch to grub.cfg' will be changed to grubtest.cfg. This is so that the main config still links (in the menu) to grubtest.cfg, so that you don't have to manually switch to it, in case you ever want to follow this guide again in the future (modifying -the already modified config). From /libreboot\_util/cbfstool, do:\ -\$ **sed -e 's:(cbfsdisk)/grub.cfg:(cbfsdisk)/grubtest.cfg:g' -e +the already modified config). From /libreboot\_util/cbfstool, do: + + # sed -e 's:(cbfsdisk)/grub.cfg:(cbfsdisk)/grubtest.cfg:g' -e + 's:Switch to grub.cfg:Switch to grubtest.cfg:g' < grubtest.cfg > -grub.cfg**\ +grub.cfg Delete the grub.cfg that remained inside the ROM: @@ -203,16 +200,14 @@ Add the modified version that you just made: $ ./cbfstool libreboot.rom add -n grub.cfg -f grub.cfg -t raw -**Now you have a modified ROM. Again, refer back to +*Now you have a modified ROM. Again, refer back to [../install/\#flashrom](../install/#flashrom) for information on how to flash it. It's the same method as you used before. Shut down and then -boot up with your new configuration.** +boot up with your new configuration.* Copyright © 2014, 2015 Leah Rowe <info@minifree.org>\ Copyright © 2015 Jeroen Quint <jezza@diplomail.ch>\ - - Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License Version 1.3 or any later version published by the Free Software Foundation |