kernel-ark/drivers/lguest
Rusty Russell 5dea1c88ed lguest: use a special 1:1 linear pagetable mode until first switch.
The Host used to create some page tables for the Guest to use at the
top of Guest memory; it would then tell the Guest where this was.  In
particular, it created linear mappings for 0 and 0xC0000000 addresses
because lguest used to switch to its real page tables quite late in
boot.

However, since d50d8fe19 Linux initialized boot page tables in
head_32.S even before the "are we lguest?" boot jump.  So, now we can
simplify things: the Host pagetable code assumes 1:1 linear mapping
until it first calls the LHCALL_NEW_PGTABLE hypercall, which we now do
before we reach C code.

This also means that the Host doesn't need to know anything about the
Guest's PAGE_OFFSET.  (Non-Linux guests might not even have such a
thing).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-07-22 14:39:48 +09:30
..
x86 lguest: compile fixes 2011-01-20 21:37:29 +10:30
core.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
hypercalls.c lguest: update commentry 2009-07-30 16:03:46 +09:30
interrupts_and_traps.c headers: remove sched.h from interrupt.h 2009-10-11 11:20:58 -07:00
Kconfig Correct occurrences of 2011-05-06 09:27:55 -07:00
lg.h lguest: use a special 1:1 linear pagetable mode until first switch. 2011-07-22 14:39:48 +09:30
lguest_device.c lguest: stop using KVM hypercall mechanism 2010-04-14 21:43:56 +09:30
lguest_user.c Fix common misspellings 2011-03-31 11:26:23 -03:00
Makefile Correct occurrences of 2011-05-06 09:27:55 -07:00
page_tables.c lguest: use a special 1:1 linear pagetable mode until first switch. 2011-07-22 14:39:48 +09:30
README lguest: documentation I: Preparation 2007-07-26 11:35:16 -07:00
segments.c lguest: fix bug in setting guest GDT entry 2010-01-04 12:33:33 -08:00

Welcome, friend reader, to lguest.

Lguest is an adventure, with you, the reader, as Hero.  I can't think of many
5000-line projects which offer both such capability and glimpses of future
potential; it is an exciting time to be delving into the source!

But be warned; this is an arduous journey of several hours or more!  And as we
know, all true Heroes are driven by a Noble Goal.  Thus I offer a Beer (or
equivalent) to anyone I meet who has completed this documentation.

So get comfortable and keep your wits about you (both quick and humorous).
Along your way to the Noble Goal, you will also gain masterly insight into
lguest, and hypervisors and x86 virtualization in general.

Our Quest is in seven parts: (best read with C highlighting turned on)

I) Preparation
	- In which our potential hero is flown quickly over the landscape for a
	  taste of its scope.  Suitable for the armchair coders and other such
	  persons of faint constitution.

II) Guest
	- Where we encounter the first tantalising wisps of code, and come to
	  understand the details of the life of a Guest kernel.

III) Drivers
	- Whereby the Guest finds its voice and become useful, and our
	  understanding of the Guest is completed.

IV) Launcher
	- Where we trace back to the creation of the Guest, and thus begin our
	  understanding of the Host.

V) Host
	- Where we master the Host code, through a long and tortuous journey.
	  Indeed, it is here that our hero is tested in the Bit of Despair.

VI) Switcher
	- Where our understanding of the intertwined nature of Guests and Hosts
	  is completed.

VII) Mastery
	- Where our fully fledged hero grapples with the Great Question:
	  "What next?"

make Preparation!
Rusty Russell.