usbinstall.sh: support grub-install run from loop device (makedist) and more grub.cfg customization

src/usbinstall.sh

@@ -341,7 +341,27 @@ else
    cp $ISOMOUNTDIR/boot/{initrd*,vmlinuz*} boot/
 
    # basic extlinux.conf -> grub.cfg conversion
-   echo "search --no-floppy --label --set=root openmamba_live" > $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
+   echo "\
+#
+# GRUB configuration generated by openmamba usbinstall tool
+#
+font=unicode
+set gfxmode=auto
+insmod all_video
+insmod gfxterm
+insmod gettext
+terminal_output=gfxterm
+timeout=30
+# theme
+insmod=png
+set menu_color_normal=white/black
+set menu_color_highlight=white/green
+search --no-floppy --label --set=root openmamba_live
+
+#
+# Boot entries taken from ISO bootloader
+#
+" > $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
    while read line; do
       case $line in
          "MENU LABEL "*) [ "$CURR_BRACKET_OPEN" = "1" ] && echo "}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
@@ -354,6 +374,7 @@ else
          "append "*) set -- ${line/append initrd=}
                       CURR_INITRD="$1"
                       CURR_CMDLINE="${line/append initrd=$CURR_INITRD}"
+                      CURR_CMDLINE="${CURR_CMDLINE/vga=792}"
                       echo "linux ${CURR_KERNEL} ${CURR_CMDLINE}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
                       echo "echo \"Loading ${CURR_INITRD}\"" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
                       echo "initrd ${CURR_INITRD}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
@@ -384,7 +405,7 @@ fi
 
 set_status $"Writing bootloader..."
 echo $"Writing bootloader..."
-sudo grub-install --removable --boot-directory boot/ $SELECT_USB &>>$LOGFILE || {
+sudo grub-install --modules="part_msdos part_gpt ext2" --removable --boot-directory=boot/ $SELECT_USB &>>$LOGFILE || {
       errorAndExit $"Error: failed to install bootloader into device (${SELECT_USB})"
 }
 set_pbar 90