Joe Brandt wrote:
> On Thu, 2004-07-22 at 14:52, Ian Blenke wrote:
>
>>chris lee wrote:
>>
>>
>>>if windows can boot multiple OS kernels on the same system at the same
>>>time (NT Loader) and so can linux whats to stop someone from making a
>>>co-op bootloader to run both linux and windows on the same system at
>>>the same time?
>>>
>>
>>Unfortunately, this isn't how it works.
>>
>>A bootloader is nothing more than a piece of code that loads another
>>piece of code, usually off of some media or another.
>>
>>PC bloatloaders know how to "bootstrap" from BIOS boot and legacy x86
>>real mode from the Master Boot Record (MBR) on your harddrive, loading
>>code (namely the Linux kernel or Microsoft's HAL microkernel) that
>>allows the CPU to go into protected mode and actually start to function.
>>That is all they do. They are glorified program loaders.
>>
>>Bootstrapping is how a computer "boots" after turning itself on, through
>>to when the OS is loaded and the system is usable.
>>
>>Running to Operating Systems simultaneously requires a hardware/CPU
>>Virtualizer.
>>
>>You need something like:
>>
>>A host based CPU Virtualizer (Ring 0 shim):
>> - VMWare
>> - Virtual PC (for Windows)
>> - Plex86
>> - coLinux
>>A Microkernel based virtualizer
>> - Xen, etc.
>>A CPU emulator
>> - QEMU
>> - Bochs
>> - VirtualPC (for Mac)
>>
>>etc, etc.
>>
>>Hope this helps.
>>
>
> Nothing like cold hard facts to blast a dream into the next galaxy
>
Basically, the options that currently exist for having two separate OSes
available on the same machine at the same time involve creating a virtual user
space with a simulated OS running inside it. The reason they don't actually
have co-running operating systems with all the functionality of an OS running by
itself is tied to the reason they're called "operating systems".
An OS, at its most basic, is a set of software components that allow the user
(that's you) to "operate" the physical "system", generally by way of
applications installed once the OS is running. The OS has to interface directly
with the hardware. Any OSes sufficiently different from one another to warrant
putting them on the same box together operate at the hardware interface level so
incompatibly with one another that it's at least prohibitively difficult to get
them to work thusly. Colinux, from what I've heard, seems to overcome this
issue at least somewhat, but I haven't looked into it enough to figure out how,
or even whether it really does what people seem to think it does.
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