GRUB2’s os-prober nicely finds OSs (some, no FreeBSD on ufs2) and generates a lengthy grub.cfg. Fine, but I don’t understand that much scripting yet. Excerpts:
if x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 --hint='hd0,msdos5' a13e1c0f-c157-4ee5-a1c3-67a39ebe01d1
else
search --no-floppy --fs-uuid --set=root a13e1c0f-c157-4ee5-a1c3-67a39ebe01d1
fi
font="/usr/share/grub2/unicode.pf2"
fi
Here, in particular the lengthy if-statement is obscure, I did not find references for many parameters in the GRUB2 documentation.
Same here, where I at least understand that SuSE will be started but the details again are elusive:
menuentry 'openSUSE 12.3 (on /dev/sda5)' --class 'opensuse-12-3' --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-a13e1c0f-c157-4ee5-a1c3-67a39ebe01d1'{
savedefault
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 --hint='hd0,msdos1' e8b9e1af-e836-4332-8446-d149a0c68d40
else
search --no-floppy --fs-uuid --set=root e8b9e1af-e836-4332-8446-d149a0c68d40
fi
echo 'Loading Linux 3.7.10-1.16-desktop ...'
linux /vmlinuz-3.7.10-1.16-desktop root=UUID=a13e1c0f-c157-4ee5-a1c3-67a39ebe01d1 showopts video=1366x768 resume=/dev/disk/by-id/ata-WDC_WD3200BPVT-22JJ5T0_WD-WXU1CB1S5967-part3 nosplash noquiet
echo 'Loading initial ramdisk ...'
initrd /initrd-3.7.10-1.16-desktop
Any pointers to a detailed step by step description would be appreciated 
.
