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Hot Multi-OS Switching — Why Isn't It Everywhere?
First time accepted submitter recrudescence writes "Slashdot readers might remember the Touchbook announcement from Always Innovating stirring up a lot of excitement in the Slashdot community back in 2009 (almost a year before the iPad was announced and essentially killed this off, and way before the Asus Transformer, which is essentially the same idea). The company's new product seems to support Hot multi-OS switching, supposedly with a minimal performance penalty. What seems strange to me is, why haven't other developers jumped in on this already? Macs, for instance, made a huge campaign of their products' new ability to finally support Microsoft Windows, yet (disregarding emulation options) they're still limited to booting to a single working system at any time."
Do you mean a pirated copy?
Here's the thing - multi-OS is confusing for people. No one is clammering for it because no one is going to get a device and then figure out how to load another OS on it. Think about it - how many people do you know (outside of your circle of geeks) that has a clue you can even load another OS? No manufacturer is going to preload two OS's. And, the geek community really isn't large enough to support sales of consumer devices.
People seem to be perfectly content having multiple devices. I don't know anyone who really uses Bootcamp, but I know quite a few Mac users that also have a Windows laptop laying around in case they need to use it, or the occasional VM. (Most Mac users I know seem perfectly content telling their PC brethren "I can't open that" and making them resend it in another format rather than try to figure out why their overpriced, shiny toy can't do something.) In the tablet world, there's not a lot of interoperability needed because there always seems to be An App For That.
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Some of us don't have the luxury of using only what we want. I get paid for helping my clients with their problems (normally Windows), not playing on my own system. sometimes I have to fire up Windows 7, or XP, or Server 2008 R2, or Fedora 14, while I enjoy working with Ubuntu or testing an "enthusiast" OS. Some on-line services STILL only work with Windows.
An OS is just a platform for apps. By itself, it doesn't do a whole lot. The apps are what's important. If I HAVE to run MS Office, then I have to run Windows. If I have to work on Oracle in Linux, then I need Red Hat.
I'm planning on putting either a bare-metal hypervisor, or thin Linux server, on my next laptop just so I can "Hot Multi-OS switch" according to my needs of the moment.
When you want something built, come see me. If you want correct grammar and spelling, get a F*ing liberal arts student.
Hell why not have two and pick the right tool for the job? I got myself one of the new EEE Brazos netbooks (highly recommend BTW, great performance and holds 8Gb of RAM) and one of the things that sold me on it is ExpressGate. With ExpressGate if all I want to do is surf, or chat, or listen to the tunes off my HDD I just push the EG button instead of the on button and in under 6 seconds I have a ChromeOS style net OS that adds about two hours on the battery, depending on what I'm doing.
On the other hand, if I want to fire up Audacity to do some editing? Or Word to work on a doc, or even fire up one of the games I picked up off of GOG? Hit the on button instead and I have Win 7 HP X64 waiting to do whatever I want. And the Brazos chip is a hell of a lot more like a CULV than an Atom, it is really snappy.
So why not have both? Hell you can fire up EG from within Win 7 if you want some "Yo dawg" OS in a OS style action. But it isn't like there aren't plenty of choices out there so in this case you can have your cake and eat it too.
ACs don't waste your time replying, your posts are never seen by me.
Some people figured out how to use rEFIt do that with Linux and Mac OS X. But too many people used this without understanding what they were doing, and the rEFIt author was annoyed with having to support that, so he fixed rEFIt such that it would no longer permit this.
/, /usr, and /home are likely to always be busy.
The main reason it cannot work is the file systems. If you have the same file system mounted read/write in both systems you are going to corrupt it. Read only access would be fine except from two problems.
Some journalling file systems cannot be mounted read only. If you tried to do this with ext3 (that's the journalling file system I have the most experience with), the ext3 driver will not respect the request to mount the file system read only. What will happen is that the first system will leave the file system in a busy state. The next one that was supposed to only mount it read only will see that the file system was not cleanly unmounted and will mount it read/write, then clean up the file system, and then remount it read only.
So, even if you thought you had configured it correctly, the OS instance that was only allowed to read still wrote something. Then you switch back to the one that is allowed to write, and since it doesn't know that something has changed the disk contents behind its back (and it wouldn't have been able to deal with it, even if it had known about it), the next write is potentially going to corrupt the file system.
The other problem is that even if you can mount the file system completely read only, the file system driver still doesn't expect the contents to change underneath it, so once you have been in the OS instance that is allowed to change it, and then switch back, bad things may happen.
To some extent you can get around the problems by unmounting file systems before hibernating and mounting them again when restoring. But if the file system was busy and couldn't be unmounted, you will be in trouble. In particular stuff like
The safest approach would be to not access any file system from both systems. But that makes sharing data between them hard. If you were virtualizing and had both running at the same time, you could use networking file systems. But that isn't going to work when they are not running at the same time since one is always hibernated.
You have a bit of the same problems with USB attached file systems. I guess those are unmounted when the system is hibernated, but I don't know what systems do if the USB stick is busy at hibernation time. You can probably mess up things badly if you put a USB file system into a situation that is almost impossible to handle.
If you have a USB stick with no important data on it, then you can make the following experiment.
Continue in this way by alternating which machine gets to write until the media is full. Notice that at no point do you move the USB stick while the system is running, you only move it while both machines are hibernated. My guess is that you will find that management of free space gets messed up badly, and the two files will be claiming to own the same physical areas of the media.
Removable file systems tend not to be busy all the time and not likely to get into such bad situations unless you put them into challenging situations like I described. But there are file systems that you expect to be mounted and busy all the time while the system is running. On those the risk of such problems is much higher.
Do you care about the security of your wireless mouse?