What exactly is the boot loader? At installation, Fedora asked me if I wanted to install the bootloader in mbr, to which I said no, because I already had Ubuntu installed, I didn't want to rewrite it. I can always run update-grub.

But this chainload option would save me doing that. How do I set it up? If you have 12 OSs installed, can you show me a sample of your grub.cfg please?

What exactly is the boot loader? At installation, Fedora asked me if I wanted to install the bootloader in mbr, to which I said no, because I already had Ubuntu installed, I didn't want to rewrite it. I can always run update-grub.

But this chainload option would save me doing that. How do I set it up? If you have 12 OSs installed, can you show me a sample of your grub.cfg please?

I recently had this experience with Fed 17. I had a much earlier version (13, I think), and when I upgraded to 17, I found that Ubuntu's GRUB would not detect it no matter what I did with the bootloader (short of putting it in the MBR of the primary hard drive). Perusing the Fedora forums, I found that in order for "sudo update-grub" to detect it, it was necessary to mount the Fedora root partition before Ubuntu's GRUB would detect it in an update.

While undoubtedly it would work mounting the Fed partition during an update, it probably isn't absolutely necessary, since you can run "sudo update-grub" afterwards to the same effect. Good experiment just to see what happens, though.

I just wish I knew why that's the case. I've never before encountered a situation in which GRUB can't detect another OS unless the partition is mounted.

Bootloader is Grub2. My system runs with Ubuntu's grub2 installed in the MBR. Every other OS has it's bootloader installed in it's own root partition. That's how ubuntu's grub recognizes the other OSs.
Next I did edit /etc/grub.d/ in that way I only have a /etc/grub.d/40_custom file making that executable with:
sudo chmod +x /etc/grub.d/40_custom and making all the others non-executable with:

sudo chmod -x /etc/grub.d/10_linux /etc/grub.d/20_memtest86+ /etc/grub.d/30_os-prober

Then you run sudo update-grub and grub.cfg will only have what's in your /etc/grub.d/40_custom exactly as I wanted it.
Bottom line though is one bootloader in the mbr, all the others in their root partition.
Have to go, show you my grub.cfg asap.

OK Pedroski as promised
Sample of my grub.cfg file:
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
set default="0"
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi

function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}

function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}

function load_video {
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
}

insmod part_msdos
insmod ext2
set root='(hd1,msdos1)'
search --no-floppy --fs-uuid --set=root 37a8c885-a431-42a6-97e0-1f682b46274c
if loadfont /usr/share/grub/unicode.pf2 ; then
set gfxmode=auto
load_video
insmod gfxterm
insmod part_msdos
insmod ext2
set root='(hd1,msdos1)'
search --no-floppy --fs-uuid --set=root 37a8c885-a431-42a6-97e0-1f682b46274c
set locale_dir=($root)/boot/grub/locale
set lang=en_US
insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ]; then
set timeout=-1
else
set timeout=10
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
if background_color 44,0,30; then
clear
fi
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.

menuentry 'Ubuntu, with Linux 3.0.0-12-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
set gfxpayload=$linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd1,msdos1)'
search --no-floppy --fs-uuid --set=root 37a8c885-a431-42a6-97e0-1f682b46274c
linux /boot/vmlinuz-3.0.0-12-generic root=UUID=37a8c885-a431-42a6-97e0-1f682b46274c ro quiet splash vt.handoff=7
initrd /boot/initrd.img-3.0.0-12-generic
}
menuentry 'Ubuntu, with Linux 3.0.0-12-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd1,msdos1)'
search --no-floppy --fs-uuid --set=root 37a8c885-a431-42a6-97e0-1f682b46274c
echo 'Loading Linux 3.0.0-12-generic ...'
linux /boot/vmlinuz-3.0.0-12-generic root=UUID=37a8c885-a431-42a6-97e0-1f682b46274c ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.0.0-12-generic
}

menuentry "Solaris 11 in hd1,2" {
insmod ufs2
set root=(hd1,2)
chainloader +1
}

menuentry "CentOS 6.0 plus in hd1,5 (on /dev/sdb5)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos5)'
search --no-floppy --fs-uuid --set=root 7bd70f68-b192-4a48-86d5-1fd3422077c4
linux /boot/vmlinuz-2.6.32-71.29.1.el6.centos.plus.i686 ro root=UUID=7bd70f68-b192-4a48-86d5-1fd3422077c4 rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=be-latin1 crashkernel=auto rhgb quiet
initrd /boot/initramfs-2.6.32-71.29.1.el6.centos.plus.i686.img
}

menuentry "CentOS 6.0 old1 in hd1,5 (on /dev/sdb5)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos5)'
search --no-floppy --fs-uuid --set=root 7bd70f68-b192-4a48-86d5-1fd3422077c4
linux /boot/vmlinuz-2.6.32-71.29.1.el6.i686 ro root=UUID=7bd70f68-b192-4a48-86d5-1fd3422077c4 rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=be-latin1 crashkernel=auto rhgb quiet
initrd /boot/initramfs-2.6.32-71.29.1.el6.i686.img
}
menuentry "centos 6.0 old2 in hd1,5 (on /dev/sdb5)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos5)'
search --no-floppy --fs-uuid --set=root 7bd70f68-b192-4a48-86d5-1fd3422077c4
linux /boot/vmlinuz-2.6.32-71.el6.i686 ro root=UUID=7bd70f68-b192-4a48-86d5-1fd3422077c4 rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=be-latin1 crashkernel=auto rhgb quiet
initrd /boot/initramfs-2.6.32-71.el6.i686.img
}

menuentry "Mandriva 2011 in hd1,6 (on /dev/sdb6)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos6)'
search --no-floppy --fs-uuid --set=root 74add841-adca-47d1-93ca-23a5a3df4ae1
linux /boot/vmlinuz-2.6.38.7-desktop-1mnb2 BOOT_IMAGE=Mandriva_2011_in_hd1,6 root=/dev/sdb6 ro quiet splash vga=788
initrd (hd1,6)/boot/initramfs-2.6.38.7-desktop-1mnb2.img
}
menuentry "Mandriva failsafe in hd1,6 (on /dev/sdb6)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos6)'
search --no-floppy --fs-uuid --set=root 74add841-adca-47d1-93ca-23a5a3df4ae1
linux /boot/vmlinuz BOOT_IMAGE=failsafe root=UUID=74add841-adca-47d1-93ca-23a5a3df4ae1 nokmsboot failsafe
initrd (hd1,6)/boot/initrd.img
}
menuentry "Kubuntu 11.10 in hd1,7 (on /dev/sdb7)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos7)'
search --no-floppy --fs-uuid --set=root c37d2c9d-2ae5-4cae-ae02-2db05e61d854
linux /boot/vmlinuz-3.0.0-12-generic root=UUID=c37d2c9d-2ae5-4cae-ae02-2db05e61d854 ro quiet splash vt.handoff=7
initrd /boot/initrd.img-3.0.0-12-generic
}
menuentry "Kubuntu 11.10 in hd1,7 (recovery mode) (on /dev/sdb7)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos7)'
search --no-floppy --fs-uuid --set=root c37d2c9d-2ae5-4cae-ae02-2db05e61d854
linux /boot/vmlinuz-3.0.0-12-generic root=UUID=c37d2c9d-2ae5-4cae-ae02-2db05e61d854 ro recovery nomodeset
initrd /boot/initrd.img-3.0.0-12-generic
}
menuentry "Debian 6.0 in hd1,8 (on /dev/sdb8)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos8)'
search --no-floppy --fs-uuid --set=root 3262ea73-757f-452d-b387-09ab12e76739
linux /boot/vmlinuz-2.6.32-5-686 root=UUID=3262ea73-757f-452d-b387-09ab12e76739 ro quiet
initrd /boot/initrd.img-2.6.32-5-686
}
menuentry "Debian 6.0 in hd1,8 (recovery mode) (on /dev/sdb8)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos8)'
search --no-floppy --fs-uuid --set=root 3262ea73-757f-452d-b387-09ab12e76739
linux /boot/vmlinuz-2.6.32-5-686 root=UUID=3262ea73-757f-452d-b387-09ab12e76739 ro single
initrd /boot/initrd.img-2.6.32-5-686
}
menuentry "Sabayon 7 in hd1,9 (on /dev/sdb9)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos9)'
search --no-floppy --fs-uuid --set=root b7e803df-8f2a-4b62-88f7-1a6022c91c09
linux /boot/kernel-genkernel-x86-3.0.0-sabayon ro init=/linuxrc splash=silent,theme:sabayon vga=791 console=tty1 quiet dokeymap keymap=be domdadm resume=swap:UUID=56e620eb-7d4c-43d8-9597-30248f59b13e real_resume=UUID=56e620eb-7d4c-43d8-9597-30248f59b13e root=UUID=b7e803df-8f2a-4b62-88f7-1a6022c91c09 docrypt
initrd /boot/initramfs-genkernel-x86-3.0.0-sabayon
}
menuentry "Sabayon 7 in hd1,9 (recovery mode) (on /dev/sdb9)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos9)'
search --no-floppy --fs-uuid --set=root b7e803df-8f2a-4b62-88f7-1a6022c91c09
linux /boot/kernel-genkernel-x86-3.0.0-sabayon ro single init_opts=single init=/linuxrc splash=verbose,theme:sabayon vga=791 console=tty1 quiet dokeymap keymap=be domdadm resume=swap:UUID=56e620eb-7d4c-43d8-9597-30248f59b13e real_resume=UUID=56e620eb-7d4c-43d8-9597-30248f59b13e root=UUID=b7e803df-8f2a-4b62-88f7-1a6022c91c09 docrypt
initrd /boot/initramfs-genkernel-x86-3.0.0-sabayon
}

menuentry "Fedora FC16 (Verne) (on /dev/sdb10)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos10)'
search --no-floppy --fs-uuid --set=root d260ce91-c2d6-469e-a22e-4d734b523083
linux /boot/vmlinuz-3.1.0-7.fc16.i686 root=/dev/sdb10
initrd /boot/initramfs-3.1.0-7.fc16.i686.img
}


menuentry "slackware 13.37 in hd1,11 (on /dev/sdb11)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos11)'
search --no-floppy --fs-uuid --set=root 871ba06c-0fb1-4049-afff-7a1abc027752
linux /boot/vmlinuz root=/dev/sdb11 ro vt.default_utf8=0 vga = normal
}
menuentry "OpenSUSE 11.4 in hd1,12 (on /dev/sdb12)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos12)'
search --no-floppy --fs-uuid --set=root cfc310eb-ffb6-4e30-8835-5d2ace7c90a7
linux /boot/vmlinuz-2.6.37.6-0.7-desktop root=/dev/disk/by-id/ata-WDC_WD2500AAJS-00VTA0_WD-WMART0531724-part12 resume=/dev/disk/by-id/ata-WDC_WD2500AAJS-00VTA0_WD-WMART0531724-part3 splash=silent quiet showopts vga=0x31a
initrd /boot/initrd-2.6.37.6-0.7-desktop
}
menuentry "Failsafe OpenSUSE 11.4 in hd1,12 (on /dev/sdb12)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos12)'
search --no-floppy --fs-uuid --set=root cfc310eb-ffb6-4e30-8835-5d2ace7c90a7
linux /boot/vmlinuz-2.6.37.6-0.7-desktop root=/dev/disk/by-id/ata-WDC_WD2500AAJS-00VTA0_WD-WMART0531724-part12 showopts apm=off noresume nosmp maxcpus=0 edd=off powersaved=off nohz=off highres=off processor.max_cstate=1 nomodeset x11failsafe vga=0x31a
initrd /boot/initrd-2.6.37.6-0.7-desktop
}


menuentry "PCBSD 8.2 in hd2,1" {
insmod ufs2
set root=(hd2,1)
chainloader +1
}

menuentry "MEPIS 11,0 in hd2,2 (on /dev/sdc2)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos2)'
search --no-floppy --fs-uuid --set=root 56ded2a8-9da8-4911-a95f-64534219b564
linux /boot/vmlinuz root=/dev/sdg2 nomce quiet splash vga=788
initrd /boot/initrd.img
}
menuentry "MEPIS 11.0 old in hd2,2 (on /dev/sdc2)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos2)'
search --no-floppy --fs-uuid --set=root 56ded2a8-9da8-4911-a95f-64534219b564
linux /boot/vmlinuz-2.6.36-1-mepis-smp root=/dev/sdg2 nomce quiet splash vga=788
initrd /boot/initrd.img-2.6.36-1-mepis-smp
}

menuentry "PCLinuxOS 2010.12 in hd2,3)" {
insmod ext2
set root=(hd2,3)
chainloader +1
}

menuentry "Kanotix 2011-05 in hd2,5 (on /dev/sdc5)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos5)'
search --no-floppy --fs-uuid --set=root 9e475759-52bb-43a2-abdd-2ebe98dbb160
linux /boot/vmlinuz-2.6.38-7-generic root=UUID=9e475759-52bb-43a2-abdd-2ebe98dbb160 ro quiet splash
initrd /boot/initrd.img-2.6.38-7-generic
}
menuentry "Kanotix 2011-05 in hd2,5 (recovery mode) (on /dev/sdc5)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos5)'
search --no-floppy --fs-uuid --set=root 9e475759-52bb-43a2-abdd-2ebe98dbb160
linux /boot/vmlinuz-2.6.38-7-generic root=UUID=9e475759-52bb-43a2-abdd-2ebe98dbb160 ro single
initrd /boot/initrd.img-2.6.38-7-generic
}
menuentry "Linux Mint 11 in hd2,7 (/dev/sdg7) (on /dev/sdc7)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos7)'
search --no-floppy --fs-uuid --set=root 3b43e806-7838-43bf-a853-920a1781723a
linux /boot/vmlinuz-2.6.38-8-generic root=UUID=3b43e806-7838-43bf-a853-920a1781723a ro quiet splash vt.handoff=7
initrd /boot/initrd.img-2.6.38-8-generic
}
menuentry "Linux Mint 11 in hd2,7 (/dev/sdg7) recovery mode (on /dev/sdc7)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos7)'
search --no-floppy --fs-uuid --set=root 3b43e806-7838-43bf-a853-920a1781723a
linux /boot/vmlinuz-2.6.38-8-generic root=UUID=3b43e806-7838-43bf-a853-920a1781723a ro single
initrd /boot/initrd.img-2.6.38-8-generic
}

menuentry "Dell Utility Partition (on /dev/sda1)" --class windows --class os {
insmod part_msdos
insmod fat
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 07d6-0c0c
drivemap -s (hd0) ${root}
chainloader +1
}
menuentry "Windows XP Media Center Edition (on /dev/sda2)" --class windows --class os {
insmod part_msdos
insmod ntfs
set root='(hd0,msdos2)'
search --no-floppy --fs-uuid --set=root 6CF4F025F4EFEEF0
drivemap -s (hd0) ${root}
chainloader +1
}

And my /etc/grub.d/40_custom file (essentially the same)

#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.

menuentry 'Ubuntu, with Linux 3.0.0-12-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
set gfxpayload=$linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd1,msdos1)'
search --no-floppy --fs-uuid --set=root 37a8c885-a431-42a6-97e0-1f682b46274c
linux /boot/vmlinuz-3.0.0-12-generic root=UUID=37a8c885-a431-42a6-97e0-1f682b46274c ro quiet splash vt.handoff=7
initrd /boot/initrd.img-3.0.0-12-generic
}
menuentry 'Ubuntu, with Linux 3.0.0-12-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd1,msdos1)'
search --no-floppy --fs-uuid --set=root 37a8c885-a431-42a6-97e0-1f682b46274c
echo 'Loading Linux 3.0.0-12-generic ...'
linux /boot/vmlinuz-3.0.0-12-generic root=UUID=37a8c885-a431-42a6-97e0-1f682b46274c ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.0.0-12-generic
}

menuentry "Solaris 11 in hd1,2" {
insmod ufs2
set root=(hd1,2)
chainloader +1
}

menuentry "CentOS 6.0 plus in hd1,5 (on /dev/sdb5)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos5)'
search --no-floppy --fs-uuid --set=root 7bd70f68-b192-4a48-86d5-1fd3422077c4
linux /boot/vmlinuz-2.6.32-71.29.1.el6.centos.plus.i686 ro root=UUID=7bd70f68-b192-4a48-86d5-1fd3422077c4 rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=be-latin1 crashkernel=auto rhgb quiet
initrd /boot/initramfs-2.6.32-71.29.1.el6.centos.plus.i686.img
}

menuentry "CentOS 6.0 old1 in hd1,5 (on /dev/sdb5)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos5)'
search --no-floppy --fs-uuid --set=root 7bd70f68-b192-4a48-86d5-1fd3422077c4
linux /boot/vmlinuz-2.6.32-71.29.1.el6.i686 ro root=UUID=7bd70f68-b192-4a48-86d5-1fd3422077c4 rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=be-latin1 crashkernel=auto rhgb quiet
initrd /boot/initramfs-2.6.32-71.29.1.el6.i686.img
}
menuentry "centos 6.0 old2 in hd1,5 (on /dev/sdb5)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos5)'
search --no-floppy --fs-uuid --set=root 7bd70f68-b192-4a48-86d5-1fd3422077c4
linux /boot/vmlinuz-2.6.32-71.el6.i686 ro root=UUID=7bd70f68-b192-4a48-86d5-1fd3422077c4 rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=be-latin1 crashkernel=auto rhgb quiet
initrd /boot/initramfs-2.6.32-71.el6.i686.img
}

menuentry "Mandriva 2011 in hd1,6 (on /dev/sdb6)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos6)'
search --no-floppy --fs-uuid --set=root 74add841-adca-47d1-93ca-23a5a3df4ae1
linux /boot/vmlinuz-2.6.38.7-desktop-1mnb2 BOOT_IMAGE=Mandriva_2011_in_hd1,6 root=/dev/sdb6 ro quiet splash vga=788
initrd (hd1,6)/boot/initramfs-2.6.38.7-desktop-1mnb2.img
}
menuentry "Mandriva failsafe in hd1,6 (on /dev/sdb6)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos6)'
search --no-floppy --fs-uuid --set=root 74add841-adca-47d1-93ca-23a5a3df4ae1
linux /boot/vmlinuz BOOT_IMAGE=failsafe root=UUID=74add841-adca-47d1-93ca-23a5a3df4ae1 nokmsboot failsafe
initrd (hd1,6)/boot/initrd.img
}
menuentry "Kubuntu 11.10 in hd1,7 (on /dev/sdb7)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos7)'
search --no-floppy --fs-uuid --set=root c37d2c9d-2ae5-4cae-ae02-2db05e61d854
linux /boot/vmlinuz-3.0.0-12-generic root=UUID=c37d2c9d-2ae5-4cae-ae02-2db05e61d854 ro quiet splash vt.handoff=7
initrd /boot/initrd.img-3.0.0-12-generic
}
menuentry "Kubuntu 11.10 in hd1,7 (recovery mode) (on /dev/sdb7)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos7)'
search --no-floppy --fs-uuid --set=root c37d2c9d-2ae5-4cae-ae02-2db05e61d854
linux /boot/vmlinuz-3.0.0-12-generic root=UUID=c37d2c9d-2ae5-4cae-ae02-2db05e61d854 ro recovery nomodeset
initrd /boot/initrd.img-3.0.0-12-generic
}
menuentry "Debian 6.0 in hd1,8 (on /dev/sdb8)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos8)'
search --no-floppy --fs-uuid --set=root 3262ea73-757f-452d-b387-09ab12e76739
linux /boot/vmlinuz-2.6.32-5-686 root=UUID=3262ea73-757f-452d-b387-09ab12e76739 ro quiet
initrd /boot/initrd.img-2.6.32-5-686
}
menuentry "Debian 6.0 in hd1,8 (recovery mode) (on /dev/sdb8)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos8)'
search --no-floppy --fs-uuid --set=root 3262ea73-757f-452d-b387-09ab12e76739
linux /boot/vmlinuz-2.6.32-5-686 root=UUID=3262ea73-757f-452d-b387-09ab12e76739 ro single
initrd /boot/initrd.img-2.6.32-5-686
}
menuentry "Sabayon 7 in hd1,9 (on /dev/sdb9)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos9)'
search --no-floppy --fs-uuid --set=root b7e803df-8f2a-4b62-88f7-1a6022c91c09
linux /boot/kernel-genkernel-x86-3.0.0-sabayon ro init=/linuxrc splash=silent,theme:sabayon vga=791 console=tty1 quiet dokeymap keymap=be domdadm resume=swap:UUID=56e620eb-7d4c-43d8-9597-30248f59b13e real_resume=UUID=56e620eb-7d4c-43d8-9597-30248f59b13e root=UUID=b7e803df-8f2a-4b62-88f7-1a6022c91c09 docrypt
initrd /boot/initramfs-genkernel-x86-3.0.0-sabayon
}
menuentry "Sabayon 7 in hd1,9 (recovery mode) (on /dev/sdb9)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos9)'
search --no-floppy --fs-uuid --set=root b7e803df-8f2a-4b62-88f7-1a6022c91c09
linux /boot/kernel-genkernel-x86-3.0.0-sabayon ro single init_opts=single init=/linuxrc splash=verbose,theme:sabayon vga=791 console=tty1 quiet dokeymap keymap=be domdadm resume=swap:UUID=56e620eb-7d4c-43d8-9597-30248f59b13e real_resume=UUID=56e620eb-7d4c-43d8-9597-30248f59b13e root=UUID=b7e803df-8f2a-4b62-88f7-1a6022c91c09 docrypt
initrd /boot/initramfs-genkernel-x86-3.0.0-sabayon
}

menuentry "Fedora FC16 (Verne) (on /dev/sdb10)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos10)'
search --no-floppy --fs-uuid --set=root d260ce91-c2d6-469e-a22e-4d734b523083
linux /boot/vmlinuz-3.1.0-7.fc16.i686 root=/dev/sdb10
initrd /boot/initramfs-3.1.0-7.fc16.i686.img
}


menuentry "slackware 13.37 in hd1,11 (on /dev/sdb11)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos11)'
search --no-floppy --fs-uuid --set=root 871ba06c-0fb1-4049-afff-7a1abc027752
linux /boot/vmlinuz root=/dev/sdb11 ro vt.default_utf8=0 vga = normal
}
menuentry "OpenSUSE 11.4 in hd1,12 (on /dev/sdb12)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos12)'
search --no-floppy --fs-uuid --set=root cfc310eb-ffb6-4e30-8835-5d2ace7c90a7
linux /boot/vmlinuz-2.6.37.6-0.7-desktop root=/dev/disk/by-id/ata-WDC_WD2500AAJS-00VTA0_WD-WMART0531724-part12 resume=/dev/disk/by-id/ata-WDC_WD2500AAJS-00VTA0_WD-WMART0531724-part3 splash=silent quiet showopts vga=0x31a
initrd /boot/initrd-2.6.37.6-0.7-desktop
}
menuentry "Failsafe OpenSUSE 11.4 in hd1,12 (on /dev/sdb12)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd1,msdos12)'
search --no-floppy --fs-uuid --set=root cfc310eb-ffb6-4e30-8835-5d2ace7c90a7
linux /boot/vmlinuz-2.6.37.6-0.7-desktop root=/dev/disk/by-id/ata-WDC_WD2500AAJS-00VTA0_WD-WMART0531724-part12 showopts apm=off noresume nosmp maxcpus=0 edd=off powersaved=off nohz=off highres=off processor.max_cstate=1 nomodeset x11failsafe vga=0x31a
initrd /boot/initrd-2.6.37.6-0.7-desktop
}


menuentry "PCBSD 8.2 in hd2,1" {
insmod ufs2
set root=(hd2,1)
chainloader +1
}

menuentry "MEPIS 11,0 in hd2,2 (on /dev/sdc2)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos2)'
search --no-floppy --fs-uuid --set=root 56ded2a8-9da8-4911-a95f-64534219b564
linux /boot/vmlinuz root=/dev/sdg2 nomce quiet splash vga=788
initrd /boot/initrd.img
}
menuentry "MEPIS 11.0 old in hd2,2 (on /dev/sdc2)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos2)'
search --no-floppy --fs-uuid --set=root 56ded2a8-9da8-4911-a95f-64534219b564
linux /boot/vmlinuz-2.6.36-1-mepis-smp root=/dev/sdg2 nomce quiet splash vga=788
initrd /boot/initrd.img-2.6.36-1-mepis-smp
}

menuentry "PCLinuxOS 2010.12 in hd2,3)" {
insmod ext2
set root=(hd2,3)
chainloader +1
}

menuentry "Kanotix 2011-05 in hd2,5 (on /dev/sdc5)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos5)'
search --no-floppy --fs-uuid --set=root 9e475759-52bb-43a2-abdd-2ebe98dbb160
linux /boot/vmlinuz-2.6.38-7-generic root=UUID=9e475759-52bb-43a2-abdd-2ebe98dbb160 ro quiet splash
initrd /boot/initrd.img-2.6.38-7-generic
}
menuentry "Kanotix 2011-05 in hd2,5 (recovery mode) (on /dev/sdc5)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos5)'
search --no-floppy --fs-uuid --set=root 9e475759-52bb-43a2-abdd-2ebe98dbb160
linux /boot/vmlinuz-2.6.38-7-generic root=UUID=9e475759-52bb-43a2-abdd-2ebe98dbb160 ro single
initrd /boot/initrd.img-2.6.38-7-generic
}
menuentry "Linux Mint 11 in hd2,7 (/dev/sdg7) (on /dev/sdc7)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos7)'
search --no-floppy --fs-uuid --set=root 3b43e806-7838-43bf-a853-920a1781723a
linux /boot/vmlinuz-2.6.38-8-generic root=UUID=3b43e806-7838-43bf-a853-920a1781723a ro quiet splash vt.handoff=7
initrd /boot/initrd.img-2.6.38-8-generic
}
menuentry "Linux Mint 11 in hd2,7 (/dev/sdg7) recovery mode (on /dev/sdc7)" --class gnu-linux --class gnu --class os {
insmod part_msdos
insmod ext2
set root='(hd2,msdos7)'
search --no-floppy --fs-uuid --set=root 3b43e806-7838-43bf-a853-920a1781723a
linux /boot/vmlinuz-2.6.38-8-generic root=UUID=3b43e806-7838-43bf-a853-920a1781723a ro single
initrd /boot/initrd.img-2.6.38-8-generic
}

menuentry "Dell Utility Partition (on /dev/sda1)" --class windows --class os {
insmod part_msdos
insmod fat
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 07d6-0c0c
drivemap -s (hd0) ${root}
chainloader +1
}
menuentry "Windows XP Media Center Edition (on /dev/sda2)" --class windows --class os {
insmod part_msdos
insmod ntfs
set root='(hd0,msdos2)'
search --no-floppy --fs-uuid --set=root 6CF4F025F4EFEEF0
drivemap -s (hd0) ${root}
chainloader +1
}


As you can see I only work with my selfmade 40_custom file because it gives exactly what I want when I start my PC.
I just make my choice from the OS menu and I go.
Hope this helps.

Please edit your post and embed the content of that file in [code][/code]-tags. You can easily do that in the advanced editot with highlighting the content and pressing the #-symbol above the editor. This will make your post much easier to read.

Ok thanks for the sample grub.cfg

So whatever you put after ### BEGIN /etc/grub.d/40_custom ### will not be overwritten by update-grub.

But when your other systems update the kernel, what do you do? You don't seem to have all of them 'chainloaded', which means the entry will not be the newest kernel.

menuentry "PCLinuxOS 2010.12 in hd2,3)" {
insmod ext2
set root=(hd2,3)
chainloader +1

Do you manually update your grub.cfg? I suppose you must if you don't chainload all of your possiblities.

What is Solaris like??

You should not change things in grub.cfg at all, all of it will be overwritten when update-grub is launched. You have to add your changes to /etc/grub.d/40_custom.

Sorry about that. I was in a hurry and realized too late. Sorry

No, as TobiSGD says you never manually edit grub.cfg as it will be overwritten all the time. If you want to change something you edit your /etc/grub.d/40_custom and then you do update-grub and your grub.cfg will be updated with your latest changes.
As for upgrading I have to admit upgrading over the internet always ended in disaster for me, so what I do is save my stuff of any particular Linux I want to upgrade (and not every 6 months believe me) wipe out the partition,download the iso of the latest linux and install it in the empty partition and get my saved stuff back in.
It's a bit time-consuming but it works. And you know the saying "when your system works,don't try to fix it"

As for Solaris (a UNIX,not a Linux)I only installed it because I wanted to prove to myself I could do it and it works! Be aware though, it only installs in a primary partition like Windows(well,yes)and it has a very peculiar way of denominating your partitions so be careful not to wipe out anything!Not at all Windows or Linux-like.

A final note;of course I do not use all those OSs I have on my machine all the time. But it is great fun to have them and once in a while I use a Centos or a Sabayon or whatever.
I still regret Grub legacy as it is called today because I still think it was easier to handle for most of us but we have to go with grub2 as most linuxes do today...

If you use chainloading anyways nothing prevents you from using Grub legacy, Lilo, sys/extlinux or any other bootloader that supports chainloading.

Sounds like a very complicated way of doing things, saving and reinstalling. I never have any trouble updating, I do it almost daily.

sudo apt-get update for Ubuntu or sudo yum update for Fed.

Normally the systems will automatically check and recommend updates. I think Ubuntu uses Synaptic. As long as you have the repos you need, everything works fine! You should try it!

At first, sudo apt-get update will not update anything besides the package database, you have to launch sudo apt-get upgrade afterwards.

Anyways, exsencon didn't mean the daily security updates, but upgrading to a newer version of the distribution, which on some distributions often ends disastrous.

I use grub legacy as a boot manager on a separate sda1 50mb partition and chainloader each system, this way each system is isolated and updated with it's default boot loader. Legacy grub is easier to edit, grub4dos also works well as a manager.

Aha, if he meant 'upgrade', not 'update', then I read it wrong, sorry.

Upgrade has never worked for me either, even though Fedora say it is specifically tested! I don't even go there anymore.