2006/10/14, Blaisorblade <blaisorblade@yahoo.it>:

Since UML has been integrated in mainline, it is not any more correct to talk
about "UML patch" - that's misleading for people (including Jeff Dike).

I'm sorry, probably you misunderstood me. I didn't want to mislead anyone.
I simply want to explain what I was doing. I'm writing on my thesis that I use a patch
on vanilla sources, to get an executable guest kernel. I only want motivate my actions.
Why don't write more on what am I doing? If someone ask me "Ok, let's explain better about
your work with patching the guest kernel, what does really do that patch? etc...", What can
I reply?

parse error - what do you mean? What is the alternative to patches? You
mean "why don't you run UML on vanilla hosts"? The answer is "we can, but
it's slower".

Ok, thanks...  but.. that's all???

> - Why do they work?

Sorry, but the answer to this question is because they were coded by competent
programmers, and I can't find your real question (I'm not perfect at
mind-reading ;-)).

Ok, don't warry. I only want to know a simple information: what is the foundation of
patch functioning? (qual' il principio di funzionamento che sta alla base delle patch?)


I found some information on http://www.honeynet.org/papers/uml/ where I read:

Unlike VMware, UML does not require any additional virtualization software. Instead, you patch the source of the Linux kernel you want to run as your Guest OS. This UML patch converts the kernel into a executable binary called 'linux', which allows the Guest kernel to run on your system as a seperate operating system. When you run this UML patched kernel, all you need to do is give it a filesystem to use, and you now have a independent Linux system running on your computer, two for the price of one! This new kernel is a userspace application running on the real kernel (Host OS). The UML kernel receives system calls from its applications and sends/requests them to the Host kernel. There are also additional management and networking UML tools you can install on the computer that makes your life easier.

Is it right, when expecially thalks about uml patch??? It says:  " This UML patch converts the kernel into a executable binary called 'linux', which allows the Guest kernel to run on your system as a seperate operating system."
You said guest kernel works also without patch, but it's slower. Ok, but, it seems (reading above sentence) the patch is applied to get an executable binary kernel image at the end. Does it means if I don't apply uml patch, I cannot get an executable binary kernel even if I do "make linux ARCH=um" ???

bye,

Flavio.