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List:       lguest
Subject:    Re: [Lguest] Why lguest is running __PAGE_OFFSET too low?
From:       Rusty Russell <rusty () rustcorp ! com ! au>
Date:       2013-04-11 3:15:49
Message-ID: 87mwt54vl6.fsf () rustcorp ! com ! au
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Guillaume Thouvenin <guillaume.thouvenin@polymtl.ca> writes:
> Hello,
>
> I'm currently doing the quest and there is something that I don't 
> understand when the guest started. In lguest_entry(), it is said that 
> lguest is running __PAGE_OFFSET too low.

(Oops, dug this out...)

Page tables aren't set up yet.  The kernel is loaded at *physical*
address 0, and then maps itself to __PAGE_OFFSET.

This is how the non-lguest boot code works too.


> I see that lguest is not 
> running in kernel space like it should be because it is loaded by the 
> launcher that allocates the memory somewhere in userspace. Thus I 
> thought that the guest is running "launcher offset" too low. I 
> apologize if the question has already been asked but I didn't find 
> where in the archive we can search.

This feedback is good, I'll update the documentation...

> Thanks to Rusty for the quest, it is really awesome :)

You're welcome!  If you finished it, you'll know I owe you a beer :)

Hope that helps!
Rusty.
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