Arch Linux

snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Dual boot: ARCH i686 + ARCH x86_64

Hi, on my laptop I have i686, but since at work we are thinking about switching to a 64 bit environment I was wondering if it is possible to set up a dual boot i686 + x86_64, to test the 64 bit environment and continuing to work with 32 bit until the new environment is fully set up.
Since as I said I have to work with my laptop I don't want to make bad mistakes and end up with an unusable machine. Is there any pitfall in the process of installing x86_64 on my laptop? Can I simply launch the installation or there's something I have to know before I start?
Thanks everyone

Barrucadu

Member

From: York, England

Registered: 2008-03-30

Posts: 1,158

Website

Re: Dual boot: ARCH i686 + ARCH x86_64

As long as you have a 64-bit processor, you'll be fine.

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The Arch Hurd Project

snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Dual boot: ARCH i686 + ARCH x86_64

Yes, I have a P8400. I was especially wondering about grub and boot procedure: can grub boot up both the 64 and 32 bit kernels?

Barrucadu

Member

From: York, England

Registered: 2008-03-30

Posts: 1,158

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Re: Dual boot: ARCH i686 + ARCH x86_64

Yes

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The Arch Hurd Project

snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Dual boot: ARCH i686 + ARCH x86_64

Thanks Barracadu, I'll try as soon as I have some spare time!

Ranguvar

Member

Registered: 2008-08-12

Posts: 2,577

Re: Dual boot: ARCH i686 + ARCH x86_64

Why not just put a 32-bit chroot inside your 64-bit system?

http://wiki.archlinux.org/index.php/Arc … bit_system

Last edited by Ranguvar (2009-08-13 20:22:54)

Acecero

Member

Registered: 2008-06-21

Posts: 1,373

Re: Dual boot: ARCH i686 + ARCH x86_64

I think doing the 32-bit chroot would save the hassle of 2 installations, just install the x86_64.

snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Dual boot: ARCH i686 + ARCH x86_64

I think doing the 32-bit chroot would save the hassle of 2 installations, just install the x86_64.

Maybe, but as I said I already have the 32 bit version installed, and since I use my laptop to work I cannot take the risk to make some experiment and break everything. And since I never made a chroot before, I think it would be not so safe... I'll go for a plain dual boot. Thnaks for your advices, maybe I'll try it on my desktop which is already 64 bit.

snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Dual boot: ARCH i686 + ARCH x86_64

Another question, guys: can I use the same swap partition for both the operating systems? I would save about 2 GB of disk space. The two OSs won't run at the same time, so I think there's no problem in doing so: am I right?

Barrucadu

Member

From: York, England

Registered: 2008-03-30

Posts: 1,158

Website

Re: Dual boot: ARCH i686 + ARCH x86_64

Yes, that's fine. As long as you don't suspend to disk.

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snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Dual boot: ARCH i686 + ARCH x86_64

Yes, that's fine. As long as you don't suspend to disk.

Thanks, I don't use suspend to disk (I have enough troubles to make suspend to ram work ), but could you please explain why it would conflict with the single swap partition?

Nepherte

Member

From: Singapore

Registered: 2008-09-09

Posts: 427

Re: Dual boot: ARCH i686 + ARCH x86_64

When you suspend to disk (or hibernate whatever), all the data will be stored on the swap partition and when you restart the pc, it will load them again from the swap partition.

Themaister

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From: Trondheim, Norway

Registered: 2008-07-21

Posts: 652

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Re: Dual boot: ARCH i686 + ARCH x86_64

An interesting way to do it could be installing a 64-bit kernel alongside your 32-bit kernel, and have a 64-bit chroot? (of course you need to boot to the 64-bit kernel to do this.)

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ao

Member

From: 青

Registered: 2008-02-02

Posts: 16

Re: Dual boot: ARCH i686 + ARCH x86_64

You know, the 32-bit installation doubles nicely as a 32-bit chroot for the 64-bit system

snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Dual boot: ARCH i686 + ARCH x86_64

When you suspend to disk (or hibernate whatever), all the data will be stored on the swap partition and when you restart the pc, it will load them again from the swap partition.

So, if I correctly understand, hibernation would cause problems only if for example I hibernate the 32 bit system and then resume the 64 bit one, right?
For those who proposed the chroot, thanks for the suggestion but I never set up a chroot before so I'm not so confident in doing so on my business laptop. If I'll have some spare time maybe I will try to implement it on my desktop, just to learn how to do it.

ngoonee

Forum Fellow

From: Between Thailand and Singapore

Registered: 2009-03-17

Posts: 7,360

Re: Dual boot: ARCH i686 + ARCH x86_64

Hibernation in any multi-boot system is a bad idea, swap disk or no swap disk. Basically, if both installs share ANY mounts (partitions), you're almost certain to 'forget' all the changes done in between hibernates if you start up another install. Just say no.

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Allan-Volunteer on the (topic being discussed) mailn lists. You never get the people who matters attention on the forums.
jasonwryan-Installing Arch is a measure of your literacy. Maintaining Arch is a measure of your diligence. Contributing to Arch is a measure of your competence.
Griemak-Bleeding edge, not bleeding flat. Edge denotes falls will occur from time to time. Bring your own parachute.

snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Dual boot: ARCH i686 + ARCH x86_64

OK, I installed x86_64, and now boot problems are obviously here...
I had to work hard on my partitions to obtain some space for x86_64, but everything worked perfectly. Now I have 6 volumes:
  sda1: Vista recovery
  sda2: Vista
  sda3: Linux swap
  sda4: Extended partition which contains:
      sda5: Arch 32 (ext3)
      sda6: Arch 64 (ext4)
I installed Arch 64 on sda6, skipped the grub installation and then modified menu.lst on sda5 as follows:

# (0) Arch Linux
title  Arch Linux (32 bit)
root   (hd0,4)
kernel /boot/vmlinuz26 root=/dev/disk/by-uuid/a6010950-6a72-4422-98a3-0e9f7e2a49f7 ro vga=791
initrd /boot/kernel26.img

# (1) Arch Linux
title  Arch Linux Fallback (32 bit)
root   (hd0,4)
kernel /boot/vmlinuz26 root=/dev/disk/by-uuid/a6010950-6a72-4422-98a3-0e9f7e2a49f7 ro vga=791
initrd /boot/kernel26-fallback.img

# (2) Arch Linux
title  Arch Linux (custom kernel, 32 bit)
root   (hd0,4)
kernel /boot/vmlinuz26-NICK root=/dev/disk/by-uuid/a6010950-6a72-4422-98a3-0e9f7e2a49f7 ro vga=791
initrd /boot/kernel26-NICK.img

# (3) Arch Linux
title  Arch Linux (64 bit)
root   (hd0,5)
#kernel /boot/vmlinuz26 root=/dev/disk/by-uuid/b2efd088-35b7-436c-8622-1bc58eceeb7d ro vga=791
kernel /boot/vmlinuz26 root=/dev/sda6 ro vga=791
initrd /boot/kernel26.img

# (4) Arch Linux
title  Arch Linux Fallback (64 bit)
root   (hd0,5)
kernel /boot/vmlinuz26 root=/dev/disk/by-uuid/b2efd088-35b7-436c-8622-1bc58eceeb7d ro vga=791
initrd /boot/kernel26-fallback.img

# (5) Windows
title Windows Vista
rootnoverify (hd0,1)
makeactive
chainloader +1

At boot, grub starts as normal, I choose Arch 64 and the kernel load stops, saying that the file cannot be found. I tried both with uuid and with explicit /dev/sda6 (the commented and uncommented lines on entry 3), with no result. The old 32 bit installation on sda5 works fine (I'm writing from it).
What's wrong in my procedure? Should I install grub again?
Thank you again

Last edited by snack (2009-08-19 21:24:28)

buddabrod

Member

From: Germany

Registered: 2007-02-25

Posts: 220

Re: Dual boot: ARCH i686 + ARCH x86_64

No you shouldnt. When grub has started, press "c" to get into command mode, then type your stuff in and use the grub completion (use the tab key) to find out what is correct.

snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Dual boot: ARCH i686 + ARCH x86_64

No you shouldnt. When grub has started, press "c" to get into command mode, then type your stuff in and use the grub completion (use the tab key) to find out what is correct.

I tried with grub command line. Setting root=(hd0,4) (eg., sda5) I can see the /boot directory, and tab completion works  nicely. But  when I set root=(hd0,5) (sda6), then tab completion on /boot/ will give a sequence of strange characters (someting like $%@#§*èò... ). It gives the exact same string hitting tab on /root/ or /media/ or any other directory on sda6. But the  file system is ok, sinche after booting the 32 bit sistem I can mount sda6 and correctly see all the files and folders. Maybe the grub I installed with the 32 bit system has some problems with ext4? I installed it  on January of this year, when ext4 was still not available...

buddabrod

Member

From: Germany

Registered: 2007-02-25

Posts: 220

Re: Dual boot: ARCH i686 + ARCH x86_64

Aiyye yeah there are some problems with grub and ext4. It works in most cases, but sometimes it doesnt.. Maybe you want to switch to grub2? I'm running it here on ext4 w/o problems.

snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Dual boot: ARCH i686 + ARCH x86_64

Aiyye yeah there are some problems with grub and ext4. It works in most cases, but sometimes it doesnt.. Maybe you want to switch to grub2? I'm running it here on ext4 w/o problems.

Thank you very much, grub2 did the work!! But I still have to understand why on my 2 desktops (one is i686 and the other x86_64, both ext4) grub works perfectly...