[CentOS] installing C7 on a laptop with Win7, dual boot

Mon Mar 2 04:24:47 UTC 2015
Richard <lists-centos at listmail.innovate.net>


------------ Original Message ------------
> Date: Sunday, March 01, 2015 21:50:34 -0500
> From: Fred Smith <fredex at fcshome.stoneham.ma.us>
> To: centos at centos.org
> Subject: Re: [CentOS] installing C7 on a laptop with Win7, dual
boot
>
> On Mon, Mar 02, 2015 at 02:04:24AM +0000, Richard wrote:
>> 
>> 
>> ------------ Original Message ------------
>> > Date: Sunday, March 01, 2015 20:06:26 -0500
>> > From: Fred Smith <fredex at fcshome.stoneham.ma.us>
>> > To: centos at centos.org
>> > Subject: [CentOS] installing C7 on a laptop with Win7, dual boot
>> > 
>> > Hi all!
>> > 
>> > I've just installed C7 on my netbook that already contained Win7
>> > (and also Fedora 19, which the C7 is intended to replace). The
>> > Fedora installer had found the windows installation and it
>> > appeared in the grub menu, and was bootable and worked fine.
>> > 
>> > The C7 installer did not put the windows installation into the
>> > grub menu.
>> > 
>> > with some googling I found a page at
>> > https://priteshugrankar.wordpress.com/2014/09/12/dual-booting-c
>> > ent os-7-and-windows-7/ that gives a simple recipe for fixing
>> > this problem. basically:
>> > 
>> > cp /boot/grub2/grub.cfg orig.grub.cfg
>> > grub2-mkconfig -o /boot/grub2/grub.cfg
>> > 
>> > with (on his system) the second command above producing this
>> > output:
>> > 
>> > 	[root at localhost ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
>> > 	Generating grub configuration file ...
>> > 	Found linux image: /boot/vmlinuz-3.16.2-1.el7.elrepo.x86_64
>> > 	Found initrd image:
>> > 	/boot/initramfs-3.16.2-1.el7.elrepo.x86_64.img Found linux
>> > 	image: /boot/vmlinuz-3.10.0-123.el7.x86_64 Found initrd image:
>> > 	/boot/initramfs-3.10.0-123.el7.x86_64.img Found linux image:
>> > 	/boot/vmlinuz-3.10.0-123.6.3.el7.x86_64 Found initrd image:
>> > 	/boot/initramfs-3.10.0-123.6.3.el7.x86_64.img Found linux
>> > 	image:
>> > /boot/vmlinuz-0-rescue-327fe33f3b364802871211321a2790b7 	Found
>> > initrd image:
>> > /boot/initramfs-0-rescue-327fe33f3b364802871211321a2790b7.img
>> > 	Found Windows 7 (loader) on /dev/sda1
>> > 	Found Windows 7 (loader) on /dev/sda2
>> > 	done
>> > 
>> > Unfortunately, when I did it, I got this:
>> > 
>> > Generating grub configuration file ...
>> > Found linux image: /boot/vmlinuz-3.10.0-123.el7.x86_64
>> > Found initrd image: /boot/initramfs-3.10.0-123.el7.x86_64.img
>> > Found linux image: /boot/vmlinuz-3.10.0-123.20.1.el7.x86_64
>> > Found initrd image:
>> > /boot/initramfs-3.10.0-123.20.1.el7.x86_64.img Found linux
>> > image:
>> > /boot/vmlinuz-0-rescue-c875112952114f6284f69abaa4f9a2f7 Found
>> > initrd image:
>> > /boot/initramfs-0-rescue-c875112952114f6284f69abaa4f9a2f7.img
>> > done
>> > 
>> > No mention of the windows installation.
>> > 
>> > It's not that I use the win7 installation much, but I do want to
>> > be able to do so when one of those rare occasions pops up.
>> > 
>> > Thanks in advance!
>> > 
>> > Fred
>> 
>> I too encountered this issue putting centos7 on a win7 machine.
>> The solution is to:
>> 
>> edit:   
>> 
>>     /etc/grub.d/40_custom
>> 
>> putting in:
>> 
>>     menuentry 'name' {
>> 
>>     insmod ntfs
>> 
>>     set root=(hd0,2)
>> 
>>     chainloader +1
>> 
>>     }
>> 
>> note: "name" can be anything you want (within reason), and is the
>> name that will show in the boot menu. 
> 
> So, I did this. I'm assuming that 'name' should be bare, with no
> quotes? well, I tried it both ways, makes no difference. The
> grub-mkconfig does not emit any lines about having found windows.
> its output looks the  same as what I showed in the original mail,
> above.
> 
> there are 3 windows partitions, two of which appeared in grub
> previously. Here's the entry I made:
> 
> menuentry Win-7 {
> insmod ntfs
> set root=(hd0,1)
> chainloader +1
> }
> 
> 
>> 
>> the values here:
>> 
>>     root=(hd0,2)
>> 
>> will vary based on your disk setup. if you still have your fc19
>> grub/grub2 (whichever it used) configuration file you should be
>> able to confirm the values from that.
> 
> I can still access the files (I made an image of the disk), but
> grub2 configurations are not human-readable, so I can't figure it
> out from that. however, if I look at the drive image with fdisk,
> it shows partition 2 as being bootable, so I used (hd0,1). maybe I
> s hould try (hd0,2) as an alternative...
> 
>> 
>> when done, then:
>> 
>>   grub2-mkconfig -o <output file>
>> 
>> personally, i didn't set the -o to the production grub.cfg file as
>> my preference is to make backups and check things before
>> potentially trashing a file like that, but do as you wish. when
>> you're comfortable with the generated file move it to the
>> production location and reboot.
>> 
>> 
>>     - Richard
>> 

I believe you need quotes around the "name" value, but will admit I
haven't tried without.

Correct, the grub2-mkconfig command doesn't emit lines about
windows, but it puts the above lines into the resulting
(grub2/grub.cfg) file - towards the bottom. [You could hand-edit
these lines into that file if you want, but having them in the
40_custom file means that they will be included when the grub.cfg
file is recreated after a linux kernal update.]

When you boot the machine you should see the (windows) "name" entry
at the bottom of the list of kernel options. Select it and the
machine should boot into windows.

Windows does have a couple of partitions -- the main/production
bootable one as well as a rescue one. I believe that (hd0,2) is the
default location/naming for the production/bootable one.


    - Richard