GRUB2 Poor Design Decisions
GRUB2 Poor Design Decisions
Finnbarr P. Murphy
(fpm@fpmurphy.com)
The more I use GRUB2 the more I have come to realize that some of the design decisions relating
to GRUB2 must have been made by the same committee that designed the camel and the dodo.
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/etc/default/grub This configuration file contains the GRUB2 menu settings that are read by the
/etc/grub.d/ GRUB scripts and written to /boot/grub/grub.cfg. It is intended to be the main
customization file for GRUB2 for most people, similar to /boot/grub/menu.lst in GRUB Legacy.
/etc/grub.d/ This new directory contains GRUB2 scripts. These scripts are building blocks from
which the grub.cfg file is built. When the update-grub is invoked, the scripts are read in a certain
sequence and /boot/grub/grub.cfg is created.
/boot/grub/grub.cfg This is the file that replaces GRUB Legacy’s /boot/grub/menu.lst.
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In GRUB Legacy, you simply edited /boot/grub/menu.lst to customize GRUB. Not so in GRUB2!
Obviously somebody had way too much time on their hands and decided that a simple method
which had stood the test of time – direct editing of the GRUB configuration file – should be
replaced with some far more complex for no good or discernible reason. Thus GRUB2 places its
configuration files in three separate locations:
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The documented method in GRUB2 to change a boot option or add another menu item is to edit
the /etc/default/grub configuration file, run the update-grub command which uses the scripts in
/etc/grub.d/ to create a new /boot/grub/grub.cfg file. A whole cadre of developers has sprung up to
develop GUI editors for GRUB2 configuration. Numerous technical articles has been written on
GRUB2 but users seem to be more confused than ever on how to configure GRUB2. My
recommendation is to simply directly edit /boot/grub.cfg and abandon all the other files and tools
which, in the end, simply write a new /boot/grub/grub.cfg.
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Turning to the /boot/grub directory. In GRUB Legacy this directory contained only a small number
of files. Not so with GRUB2. This directory now contains numerous files. If you use grub-install it
copies all sort files to /boot/grub. For example here is a list of the files that were installed in this
directory when I built GRUB2 v1.98 and used grub-install to install it:
acpi.mod
affs.mod
afs_be.mod
afs.mod
aout.mod
ata.mod
ata_pthru.mod
at_keyboard.mod
befs_be.mod
befs.mod
biosdisk.mod
bitmap.mod
bitmap_scale.mod
blocklist.mod
boot.img
boot.mod
bsd.mod
bufio.mod
cat.mod
cdboot.img
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gcry_rijndael.mod
gcry_rmd160.mod
gcry_seed.mod
gcry_serpent.mod
gcry_sha1.mod
gcry_sha256.mod
gcry_sha512.mod
gcry_tiger.mod
gcry_twofish.mod
gcry_whirlpool.mod
gettext.mod
gfxmenu.mod
gfxterm.mod
gptsync.mod
grubenv
gzio.mod
halt.mod
handler.lst
handler.mod
hashsum.mod
part_msdos.mod
part_sun.mod
parttool.lst
parttool.mod
password.mod
password_pbkdf2.mod
pbkdf2.mod
pci.mod
play.mod
png.mod
probe.mod
pxeboot.img
pxecmd.mod
pxe.mod
raid5rec.mod
raid6rec.mod
raid.mod
read.mod
reboot.mod
reiserfs.mod
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relocator.mod
scsi.mod
search_fs_file.mod
search_fs_uuid.mod
search_label.mod
search.mod
serial.mod
setjmp.mod
setpci.mod
sfs.mod
sh.mod
sleep.mod
tar.mod
terminal.lst
terminal.mod
terminfo.mod
test.mod
tga.mod
trig.mod
true.mod
udf.mod
ufs1.mod
ufs2.mod
uhci.mod
usb_keyboard.mod
usb.mod
usbms.mod
usbtest.mod
vbeinfo.mod
vbe.mod
vbetest.mod
vga.mod
vga_text.mod
video_fb.mod
video.lst
video.mod
videotest.mod
xfs.mod
xnu.mod
xnu_uuid.mod
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hdparm.mod
hello.mod
help.mod
hexdump.mod
hfs.mod
hfsplus.mod
iso9660.mod
jfs.mod
jpeg.mod
kernel.img
keystatus.mod
linux16.mod
linux.mod
lnxboot.img
loadenv.mod
locale
loopback.mod
lsmmap.mod
ls.mod
lspci.mod
lvm.mod
mdraid.mod
memdisk.mod
memrw.mod
minicmd.mod
minix.mod
mmap.mod
moddep.lst
msdospart.mod
multiboot2.mod
multiboot.mod
normal.mod
ntfscomp.mod
ntfs.mod
ohci.mod
part_acorn.mod
part_amiga.mod
part_apple.mod
part_gpt.mod
partmap.lst
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chain.mod
charset.mod
cmp.mod
command.lst
configfile.mod
core.img
cpio.mod
cpuid.mod
crc.mod
crypto.lst
crypto.mod
datehook.mod
date.mod
datetime.mod
device.map
diskboot.img
dm_nv.mod
drivemap.mod
echo.mod
efiemu32.o
efiemu64.o
efiemu.mod
elf.mod
example_functional_test.mod
ext2.mod
extcmd.mod
fat.mod
font.mod
fshelp.mod
fs.lst
functional_test.mod
gcry_arcfour.mod
gcry_blowfish.mod
gcry_camellia.mod
gcry_cast5.mod
gcry_crc.mod
gcry_des.mod
gcry_md4.mod
gcry_md5.mod
gcry_rfc2268.mod
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GRUB2 Poor Design Decisions
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I am on an Intel X64 platform. Why are modules for handling Amiga (part_amiga.mod) or Apple (
part_apple.mod) partitions installed on my system? Why do I need the demonstration module
hello.mod? I am never going to use them. The installation script grub-install needs to have some
intelligence added to it so that modules which are incompatible with your platform are not
installed. In addition, it would be nice if the modules could be placed in a subdirectory of
/boot/grub in order to reduce the number of files in /boot/grub. The GRUB2 variable prefix allow
you to place a prefix in front of the grub subdirectory but does not allow you to place the modules
in another directory or a subdirectory.
The build system is needlessly complicated. If I want to create a new command, say colortest, I
can place a single file colortest.c in the ../common source subdirectory (which contains to source
code for most commands, one per source file) , but then I have to add the following lines to
../conf/common.mk:
# For colortest.mod.
pkglib_MODULES += colortest.mod
colortest_mod_SOURCES = commands/colortest.c
clean-module-colortest.mod.1:
rm -f colortest.mod mod-colortest.o mod-colortest.c pre-colortest.o colortest_modcommands_colortest.o und-colortest.lst
CLEAN_MODULE_TARGETS += clean-module-colortest.mod.1
clean-module-colortest.mod-symbol.1:
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rm -f def-colortest.lst
CLEAN_MODULE_TARGETS += clean-module-colortest.mod-symbol.1
DEFSYMFILES += def-colortest.lst
mostlyclean-module-colortest.mod.1:
rm -f colortest_mod-commands_colortest.d
MOSTLYCLEAN_MODULE_TARGETS += mostlyclean-module-colortest.mod.1
UNDSYMFILES += und-colortest.lst
ifneq ($(TARGET_APPLE_CC),1)
colortest.mod: pre-colortest.o mod-colortest.o $(TARGET_OBJ2ELF)
-rm -f $@
$(TARGET_CC) $(colortest_mod_LDFLAGS) $(TARGET_LDFLAGS) -Wl,-r,-d -o $@ pre-colort
est.o mod-colortest.o
if test ! -z "$(TARGET_OBJ2ELF)"; then ./$(TARGET_OBJ2ELF) $@ || (rm -f $@; exit 1)
; fi
$(STRIP) --strip-unneeded -K grub_mod_init -K grub_mod_fini -K _grub_mod_init -K _
grub_mod_fini -R .note -R .comment $@
else
colortest.mod: pre-colortest.o mod-colortest.o $(TARGET_OBJ2ELF)
-rm -f $@
-rm -f $@.bin
$(TARGET_CC) $(colortest_mod_LDFLAGS) $(TARGET_LDFLAGS) -Wl,-r,-d -o $@.bin pre-co
lortest.o mod-colortest.o
$(OBJCONV) -f$(TARGET_MODULE_FORMAT) -nr:_grub_mod_init:grub_mod_init -nr:_grub_mo
d_fini:grub_mod_fini -wd1106 -nu -nd $@.bin $@
-rm -f $@.bin
endif
pre-colortest.o: $(colortest_mod_DEPENDENCIES) colortest_mod-commands_colortest.o
-rm -f $@
$(TARGET_CC) $(colortest_mod_LDFLAGS) $(TARGET_LDFLAGS) -Wl,-r,-d -o $@ colortest_
mod-commands_colortest.o
mod-colortest.o: mod-colortest.c
$(TARGET_CC) $(TARGET_CPPFLAGS) $(TARGET_CFLAGS) $(colortest_mod_CFLAGS) -c -o $@
$<
mod-colortest.c: $(builddir)/moddep.lst $(srcdir)/genmodsrc.sh
sh $(srcdir)/genmodsrc.sh 'colortest' $< > $@ || (rm -f $@; exit 1)
ifneq ($(TARGET_APPLE_CC),1)
def-colortest.lst: pre-colortest.o
$(NM) -g --defined-only -P -p $< | sed 's/^\([^ ]*\).*/\1 colortest/' > $@
else
def-colortest.lst: pre-colortest.o
$(NM) -g -P -p $< | grep -E '^[a-zA-Z0-9_]* [TDS]' | sed 's/^\([^ ]*\).*/\1 color
test/' > $@
endif
und-colortest.lst: pre-colortest.o
echo 'colortest' > $@
$(NM) -u -P -p $< | cut -f1 -d' ' >> $@
colortest_mod-commands_colortest.o: commands/colortest.c $(commands/colortest.c_DEPENDENCI
ES)
$(TARGET_CC) -Icommands -I$(srcdir)/commands $(TARGET_CPPFLAGS) $(TARGET_CFLAGS)
$(colortest_mod_CFLAGS) -MD -c -o $@ $<
-include colortest_mod-commands_colortest.d
clean-module-colortest_mod-commands_colortest-extra.1:
rm -f cmd-colortest_mod-commands_colortest.lst fs-colortest_mod-commands_colortest.
lst partmap-colortest_mod-commands_colortest.lst handler-colortest_mod-commands_colortest.
lst parttool-colortest_mod-commands_colortest.lst video-colortest_mod-commands_colortest.l
st terminal-colortest_mod-commands_colortest.lst
CLEAN_MODULE_TARGETS += clean-module-colortest_mod-commands_colortest-extra.1
COMMANDFILES += cmd-colortest_mod-commands_colortest.lst
FSFILES += fs-colortest_mod-commands_colortest.lst
PARTTOOLFILES += parttool-colortest_mod-commands_colortest.lst
PARTMAPFILES += partmap-colortest_mod-commands_colortest.lst
HANDLERFILES += handler-colortest_mod-commands_colortest.lst
TERMINALFILES += terminal-colortest_mod-commands_colortest.lst
VIDEOFILES += video-colortest_mod-commands_colortest.lst
cmd-colortest_mod-commands_colortest.lst: commands/colortest.c $(commands/colortest.c_DEPE
NDENCIES) gencmdlist.sh
set -e;
$(TARGET_CC) -Icommands -I$(srcdir)/commands $(TARGET_CPPFLAGS)
$(TARGET_CFLAGS) $(colortest_mod_CFLAGS) -E $<
| sh $(srcdir)/gencmdlist.sh color
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test > $@ || (rm -f $@; exit 1)
fs-colortest_mod-commands_colortest.lst: commands/colortest.c $(commands/colortest.c_DEPEN
DENCIES) genfslist.sh
set -e;
$(TARGET_CC) -Icommands -I$(srcdir)/commands $(TARGET_CPPFLAGS)
$(TARGET_CFLAGS) $(colortest_mod_CFLAGS) -E $<
| sh $(srcdir)/genfslist.sh colort
est > $@ || (rm -f $@; exit 1)
parttool-colortest_mod-commands_colortest.lst: commands/colortest.c $(commands/colortest.c
_DEPENDENCIES) genparttoollist.sh
set -e;
$(TARGET_CC) -Icommands -I$(srcdir)/commands $(TARGET_CPPFLAGS)
$(TARGET_CFLAGS) $(colortest_mod_CFLAGS) -E $<
| sh $(srcdir)/genparttoollist.sh
colortest > $@ || (rm -f $@; exit 1)
partmap-colortest_mod-commands_colortest.lst: commands/colortest.c $(commands/colortest.c_
DEPENDENCIES) genpartmaplist.sh
set -e;
$(TARGET_CC) -Icommands -I$(srcdir)/commands $(TARGET_CPPFLAGS)
$(TARGET_CFLAGS) $(colortest_mod_CFLAGS) -E $<
| sh $(srcdir)/genpartmaplist.sh c
olortest > $@ || (rm -f $@; exit 1)
handler-colortest_mod-commands_colortest.lst: commands/colortest.c $(commands/colortest.c_
DEPENDENCIES) genhandlerlist.sh
set -e;
$(TARGET_CC) -Icommands -I$(srcdir)/commands $(TARGET_CPPFLAGS)
$(TARGET_CFLAGS) $(colortest_mod_CFLAGS) -E $<
| sh $(srcdir)/genhandlerlist.sh c
olortest > $@ || (rm -f $@; exit 1)
terminal-colortest_mod-commands_colortest.lst: commands/colortest.c $(commands/colortest.c
_DEPENDENCIES) genterminallist.sh
set -e;
$(TARGET_CC) -Icommands -I$(srcdir)/commands $(TARGET_CPPFLAGS)
$(TARGET_CFLAGS) $(colortest_mod_CFLAGS) -E $<
| sh $(srcdir)/genterminallist.sh
colortest > $@ || (rm -f $@; exit 1)
video-colortest_mod-commands_colortest.lst: commands/colortest.c $(commands/colortest.c_DE
PENDENCIES) genvideolist.sh
set -e;
$(TARGET_CC) -Icommands -I$(srcdir)/commands $(TARGET_CPPFLAGS)
$(TARGET_CFLAGS) $(colortest_mod_CFLAGS) -E $<
| sh $(srcdir)/genvideolist.sh col
ortest > $@ || (rm -f $@; exit 1)
colortest_mod_CFLAGS = $(COMMON_CFLAGS)
colortest_mod_LDFLAGS = $(COMMON_LDFLAGS)
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Most of the above is cookie cutter build code. I simply took the relevant lines for another module
and changed the module name to colortest. It should be possible to eliminate most of the above
with a more intelligent build environment. In some build environments I have encountered over
the years it can be as simple as adding the name of the module to a list of modules which are to be
built. Why complicate things when there are well proven simple ways to achieve the same end?
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The introduction of support for graphic screens in GRUB2 has introduced subtle problems with
color support. Colors work as expected if you use the following configuration:
root=(hd0,1)
timeout=10
default=0
if loadfont /grub/font/unicode.pf2
then
set gfxmode="1024x768x32"
set gfxpayload=keep
insmod gfxterm
insmod vbe
terminal_output gfxterm
terminal gfxterm
insmod tga
use_bg=true
background_image /grub/image/f13rockets.tga
fi
set color_normal=yellow/black
set color_highlight=blue/yellow
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GRUB2 Poor Design Decisions
set menu_color_normal=yellow/black
set menu_color_highlight=white/light-gray
menuentry "Fedora 13" {
linux /vmlinuz-2.6.33.5-124.fc13.x86_64 ro root=/dev/mapper/vg_ultra-lv_root rd_LVM_LV=
vg_ultra/lv_root rd_LVM_LV=vg_ultra/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8
SYSFONT=latarcyrheb-sun16 KEYTABLE=us rhgb quiet
initrd /initramfs-2.6.33.5-124.fc13.x86_64.img
}
but revert to using gray/black in command mode when you move the set color_normal and set
color_highlight lines to before the graphics card setting, i.e:
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timeout=10
default=0
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if loadfont /grub/font/unicode.pf2
then
set gfxmode="1024x768x32"
set gfxpayload=keep
insmod gfxterm
insmod vbe
terminal_output gfxterm
terminal gfxterm
insmod tga
use_bg=true
background_image /grub/image/f13rockets.tga
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set color_normal=yellow/black
set color_highlight=blue/yellow
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set menu_color_normal=yellow/black
set menu_color_highlight=white/light-gray
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menuentry "Fedora 13" {
linux /vmlinuz-2.6.33.5-124.fc13.x86_64 ro root=/dev/mapper/vg_ultra-lv_root rd_LVM_LV=
vg_ultra/lv_root rd_LVM_LV=vg_ultra/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8
SYSFONT=latarcyrheb-sun16 KEYTABLE=us rhgb quiet
initrd /initramfs-2.6.33.5-124.fc13.x86_64.img
}
It took me a while to understand what was going on when I first encountered this issue. The
default color in command mode was gray/black even though the set command showed that the
color settings were correct.
Finally, for no good reason the development sources have a dependency on Ruby. See autogen.sh,
genmk.rb, configure.ac and configure. Why? Probably because the original version of GRUB2 was
written by a Japanese programmer. Requiring Ruby for GRUB2 development is a needless
complication of a relatively simple process. Any dependency on Ruby should be removed.
Contrary to what you may be thinking, I actually like GRUB2. It is a huge improvement over GRUB
Legacy. All my GNU/Linux systems now use it and I am an active developer of GRUB2 modules. I
just think that the main developers of GRUB2 have managed to seriously complicate a relatively
simple piece of software from a user’s perspective. However from a developer’s perspective,
except for certain functionality such as EFI support, the source code is well structured and
partitioned and there is good built-in support for extensions.
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