[PATCH v3 02/11] grub.cfg: support ESP, btrfs subvols and extlinux

[Leah Rowe]

From: Leah Rowe <leah@libreboot.org>

This is backported from lbmk at revision:
09bed9a4c3257dbf9b4d59975db0071472ed67eb

In comparison to the GNU Boot configuration, Libreboot's
GRUB configuration provides the following improvements:

* Support for scanning of BTRFS sub volumes, on most setups.
* Support for scanning syslinux and extlinux configs, in
  the main "Load Operating System" menuentry. This will make
  distros automatically boot in most cases, where they use
  extlinux/syslinux instead of GRUB.
* Support for scanning EFI System Partitions, when scanning
  for GRUB, Syslinux and Extlinux configuration files. This
  adds support for UEFI-based distro installations; the GNU
  Boot supported mainboards are all BIOS-based, but the user
  may have transferred an HDD/SSD from another system, where
  UEFI was used. On UEFI-based systems, there is a special FAT
  partition called the ESP (EFI System Partition) that boot
  loaders and configurations are installed to.
* The ESP support is also extended to USB-based booting. This
  increases support out of the box for more distro installers,
  many of which are now UEFI-only, or only well-tested for UEFI.
  Many distros today now use *GRUB* (built for UEFI) on their
  install media, but these can also be used on bare metal setups
  such as GNU Boot's GRUB payload.
* The fallback entry was removed, that assumed /dev/sda1 as
  the root partition; where scanning of GRUB configurations
  failed, GNU Boot GRUB would try this fallback logic, but such
  logic may in some cases result in the system being booted,
  in such a way that *breaks* the user's distro, so it's better
  that GNU Boot only scan for GRUB/Extlinux/Syslinux configs
  and return with an error if none are found. This is also how
  Libreboot does it nowadays.

With this, and the previous patches that I've committed, GNU
Boot's GRUB setup should now be in feature parity with Lbreboot.

Signed-off-by: Leah Rowe <leah@libreboot.org>
---
 resources/grub/config/grub.cfg | 77 +++++++++++++++-------------------
 1 file changed, 34 insertions(+), 43 deletions(-)

diff --git a/resources/grub/config/grub.cfg b/resources/grub/config/grub.cfg
index 4f5177b..6e87b67 100644
--- a/resources/grub/config/grub.cfg
+++ b/resources/grub/config/grub.cfg
@@ -33,7 +33,9 @@ set grub_scan_disk="both"
 keymap usqwerty
 function try_user_config {
        set root="${1}"
-       for dir in boot grub grub2 boot/grub boot/grub2; do
+
+       # The @/... entries are for cases where the BTRFS filesystem is being 
used
+       for dir in boot grub grub2 boot/grub boot/grub2 @/boot @/grub @/grub2 
@/boot/grub @/boot/grub2; do
                for name in '' gnuboot_ osboot_ autoboot_ coreboot_; do
                        if [ -f /"${dir}"/"${name}"grub.cfg ]; then
                                unset superusers
@@ -56,16 +58,20 @@ function search_grub {
 
 function try_isolinux_config {
        set root="${1}"
-       for dir in '' /boot; do
+       for dir in '' /boot /EFI /boot/EFI /@ /@/boot /@/boot/EFI /@/EFI; do
                if [ -f "${dir}"/isolinux/isolinux.cfg ]; then
                        syslinux_configfile -i "${dir}"/isolinux/isolinux.cfg
                elif [ -f "${dir}"/syslinux/syslinux.cfg ]; then
                        syslinux_configfile -s "${dir}"/syslinux/syslinux.cfg
+               elif [ -f "${dir}"/syslinux/extlinux.conf ]; then
+                       syslinux_configfile -s "${dir}"/syslinux/extlinux.conf
+               elif [ -f "${dir}"/extlinux/extlinux.conf ]; then
+                       syslinux_configfile -s "${dir}"/extlinux/extlinux.conf
                fi
        done
 }
 function search_isolinux {
-       echo "\nAttempting to parse isolinux/syslinux config from '${1}' 
devices"
+       echo "\nAttempting to parse iso/sys/extlinux config from '${1}' devices"
        for i in 0 1 2 3 4 5 6 7 8 9 10 11; do
                for part in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; 
do
                        try_isolinux_config "(${1}${i},${part})"
@@ -75,20 +81,28 @@ function search_isolinux {
        done
        echo # Insert newline
 }
+function try_bootcfg {
+       try_user_config "${1}"
+       try_isolinux_config "${1}"
+}
+function search_bootcfg {
+       search_grub "${1}"
+       search_isolinux "${1}"
+}
 menuentry 'Load Operating System (incl. fully encrypted disks)  [o]' 
--hotkey='o' {
 
        if [ "${grub_scan_disk}" != "ata" ]; then
-               search_grub ahci
+               search_bootcfg ahci
        fi
        if [ "${grub_scan_disk}" != "ahci" ]; then
-               search_grub ata
+               search_bootcfg ata
        fi
 
        # grub device enumeration is very slow, so checks are hardcoded
 
        # TODO: add more strings, based on what distros set up when
        # the user select auto-partitioning on those installers
-       lvmvol="lvm/matrix-bootvol lvm/matrix-rootvol"
+       lvmvol="lvm/grubcrypt-bootvol lvm/grubcrypt-rootvol"
 
        raidvol="md/0 md/1 md/2 md/3 md/4 md/5 md/6 md/7 md/8 md/9"
 
@@ -96,7 +110,7 @@ menuentry 'Load Operating System (incl. fully encrypted 
disks)  [o]' --hotkey='o
        # TODO: optimize grub itself, and use */? here for everything
 
        for vol in ${lvmvol} ${raidvol} ; do
-               try_user_config "${vol}"
+               try_bootcfg "${vol}"
        done
 
        unset ahcidev
@@ -122,58 +136,35 @@ menuentry 'Load Operating System (incl. fully encrypted 
disks)  [o]' --hotkey='o
 
        # after cryptomount, lvm volumes might be available
        for vol in ${lvmvol}; do
-               try_user_config "${vol}"
+               try_bootcfg "${vol}"
        done
 
-       search_grub crypto
-
-       if [ "${grub_scan_disk}" != "ata" ]; then
-               # Last resort, if all else fails
-               set root=ahci0,1
-               for p in / /boot/; do
-                       if [ -f "${p}vmlinuz" ]; then
-                               linux ${p}vmlinuz root=/dev/sda1 rw
-                               if [ -f "${p}initrd.img" ]; then
-                                       initrd ${p}initrd.img
-                               fi
-                       fi
-               done
-       fi
+       search_bootcfg crypto
 
-       if [ "${grub_scan_disk}" != "ahci" ]; then
-               # Last resort (for setups that use IDE instead of SATA)
-               set root=ata0,1
-               for p in / /boot/; do
-                       if [ -f "${p}vmlinuz" ]; then
-                               linux ${p}vmlinuz root=/dev/sda1 rw
-                               if [ -f "${p}initrd.img" ]; then
-                                       initrd ${p}initrd.img
-                               fi
-                       fi
-               done
-       fi
+       for vol in lvm/* ; do
+               try_bootcfg "${vol}"
+       done
 
        true # Prevent pager requiring to accept each line instead of whole 
screen
 }
 
-menuentry 'Search ISOLINUX menu (AHCI)  [a]' --hotkey='a' {
-       search_isolinux ahci
+menuentry 'Search for GRUB/SYSLINUX/EXTLINUX/ISOLINUX on USB  [s]' 
--hotkey='s' {
+       search_bootcfg usb
 }
-menuentry 'Search ISOLINUX menu (USB)  [u]' --hotkey='u' {
-       search_isolinux usb
+menuentry 'Search for GRUB/SYSLINUX/EXTLINUX/ISOLINUX on AHCI  [a]' 
--hotkey='a' {
+       search_bootcfg ahci
 }
-menuentry 'Search ISOLINUX menu (ATA/IDE)  [d]' --hotkey='d' {
-       search_isolinux ata
+menuentry 'Search for GRUB/SYSLINUX/EXTLINUX/ISOLINUX on ATA/IDE  [d]' 
--hotkey='d' {
+       search_bootcfg ahci
 }
+if [ -f (cbfsdisk)/grubtest.cfg ]; then
 menuentry 'Load test configuration (grubtest.cfg) inside of CBFS  [t]' 
--hotkey='t' {
        set root='(cbfsdisk)'
        if [ -f /grubtest.cfg ]; then
                configfile /grubtest.cfg
        fi
 }
-menuentry 'Search for GRUB2 configuration on external media  [s]' --hotkey='s' 
{
-       search_grub usb
-}
+fi
 if [ -f (cbfsdisk)/seabios.elf ]; then
 menuentry 'Load SeaBIOS (payload) [b]' --hotkey='b' {
        set root='cbfsdisk'
-- 
2.39.2