Chainloader +1

[broncbuster]

Hey y'all,

What's Chainloader +1? I see it in my grub.conf file as it relates to my windows boot. What does it do and is it necessary? The reason i'm asking is because it my windows won't boot from grub. I have to switch the SATA cables around on my MOBO to make it boot into windows. I know the address is right (hd1,0) second hard drive, first partition, but it still wont work. When i select the windows boot, all i get is a black screen with the prompt

Windows
rootnoverify (hd1,0)
chainloader +1

What am i doing wrong? I'm using SATA HDDs all around. the two that i'm using as system disks are WD Raptors 74gb. Do i need to change it to (sd1,0)?

Thanks in advance

[Seve]

Hello:
The definition of chainloader can be found here : http://www.gnu.org/software/grub/man...ml#chainloader

If you have been switching cables around you may want to try
editing your /etc/grub.conf
and amend your entry for Windows to this:

title Windows
map (hd0) (hd1)
map (hd1) (hd0)
rootnoverify (hd1,0)
chainloader +1

And see if it helps ?

You do not need to use (sd1,0)

Seve

[broncbuster]

You are awesome! Thank you. It works flawlessly!

Now, please tell me why i needed to do that? It seems to me that all we did was two commands that cancelled each other out.

[Jman]

Now, please tell me why i needed to do that? It seems to me that all we did was two commands that cancelled each other out.

They don't cancel. It does some magic to remap the drives around and get Windows to think it's on the first drive. See the same docs page: http://www.gnu.org/software/grub/manual/grub.html#map

If you swap the drives so Windows is on the master cable, you need to change the Windows device to (hd0). Then don't use the map command.

grub has no concept of sd0 style names. It maps all devices to hd0 format.

[broncbuster]

They don't cancel. It does some magic to remap the drives around and get Windows to think it's on the first drive. See the same docs page: http://www.gnu.org/software/grub/manual/grub.html#map

If you swap the drives so Windows is on the master cable, you need to change the Windows device to (hd0). Then don't use the map command.

grub has no concept of sd0 style names. It maps all devices to hd0 format.

Gotcha, Thanks again.

[7shi]

Hi, I have a similar setup but Seve's solution does not work.

# /sbin/fdisk -l

Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1        1305    10482381   83  Linux
/dev/sda2            1306       13054    94373842+  83  Linux
/dev/sda3           13055       13152      787185   82  Linux swap / Solaris

Disk /dev/sdb: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1        1307    10498446    7  HPFS/NTFS
/dev/sdb2            1308       30400   233689522+   f  W95 Ext'd (LBA)
/dev/sdb5            1308       30400   233689491    7  HPFS/NTFS

cat /boot/grub/device.map 
# this device map was generated by anaconda
(hd0)     /dev/sda
(hd1)     /dev/sdb

title Windows XP
map (hd0) (hd1)
map (hd1) (hd0)
rootnoverify (hd1,0)
chainloader +1

When I try to boot I see the lines above and it just sits there. If i switch around the cables windows boots fine.

[stoat]

@7shi: What you posted looks okay to me. Linux boots from hd0. Windows boots from hd1. Map commands look okay. Windows NTLoader is working. GRUB is at least making it to your grub.conf file before it stops when trying to launch XP. You didn't say, but I assume that GRUB is launching Linux. Try editing your /etc/grub.conf again, and if chainloader +1 is the last line, make sure there is a blank line after it.